This is zsh.info, produced by makeinfo version 7.3 from zsh.texi.

INFO-DIR-SECTION Utilities
START-INFO-DIR-ENTRY
* ZSH: (zsh).                     The Z Shell Manual.
END-INFO-DIR-ENTRY


File: zsh.info,  Node: Arguments,  Next: Completion,  Prev: Modifying Text,  Up: Standard Widgets

18.6.4 Arguments
----------------

digit-argument (ESC-0..ESC-9) (1-9) (unbound)
     Start a new numeric argument, or add to the current one.  See also
     vi-digit-or-beginning-of-line.  This only works if bound to a key
     sequence ending in a decimal digit.

     Inside a widget function, a call to this function treats the last
     key of the key sequence which called the widget as the digit.

neg-argument (ESC--) (unbound) (unbound)
     Changes the sign of the following argument.

universal-argument
     Multiply the argument of the next command by 4.  Alternatively, if
     this command is followed by an integer (positive or negative), use
     that as the argument for the next command.  Thus digits cannot be
     repeated using this command.  For example, if this command occurs
     twice, followed immediately by forward-char, move forward sixteen
     spaces; if instead it is followed by -2, then forward-char, move
     backward two spaces.

     Inside a widget function, if passed an argument, i.e.  'zle
     universal-argument NUM', the numeric argument will be set to NUM;
     this is equivalent to 'NUMERIC=NUM'.

argument-base
     Use the existing numeric argument as a numeric base, which must be
     in the range 2 to 36 inclusive.  Subsequent use of digit-argument
     and universal-argument will input a new numeric argument in the
     given base.  The usual hexadecimal convention is used: the letter a
     or A corresponds to 10, and so on.  Arguments in bases requiring
     digits from 10 upwards are more conveniently input with
     universal-argument, since ESC-a etc.  are not usually bound to
     digit-argument.

     The function can be used with a command argument inside a
     user-defined widget.  The following code sets the base to 16 and
     lets the user input a hexadecimal argument until a key out of the
     digit range is typed:

          zle argument-base 16
          zle universal-argument


File: zsh.info,  Node: Completion,  Next: Miscellaneous,  Prev: Arguments,  Up: Standard Widgets

18.6.5 Completion
-----------------

accept-and-menu-complete
     In a menu completion, insert the current completion into the
     buffer, and advance to the next possible completion.

complete-word
     Attempt completion on the current word.

delete-char-or-list (^D) (unbound) (unbound)
     Delete the character under the cursor.  If the cursor is at the end
     of the line, list possible completions for the current word.

expand-cmd-path
     Expand the current command to its full pathname.

expand-or-complete (TAB) (unbound) (TAB)
     Attempt shell expansion on the current word.  If that fails,
     attempt completion.

expand-or-complete-prefix
     Attempt shell expansion on the current word up to cursor.

expand-history (ESC-space ESC-!) (unbound) (unbound)
     Perform history expansion on the edit buffer.

expand-word (^X*) (unbound) (unbound)
     Attempt shell expansion on the current word.

list-choices (ESC-^D) (^D =) (^D)
     List possible completions for the current word.

list-expand (^Xg ^XG) (^G) (^G)
     List the expansion of the current word.

magic-space
     Perform history expansion and insert a space into the buffer.  This
     is intended to be bound to space.

menu-complete
     Like complete-word, except that menu completion is used.  See the
     MENU_COMPLETE option.

menu-expand-or-complete
     Like expand-or-complete, except that menu completion is used.

reverse-menu-complete
     Perform menu completion, like menu-complete, except that if a menu
     completion is already in progress, move to the _previous_
     completion rather than the next.

end-of-list
     When a previous completion displayed a list below the prompt, this
     widget can be used to move the prompt below the list.


File: zsh.info,  Node: Miscellaneous,  Next: Text Objects,  Prev: Completion,  Up: Standard Widgets

18.6.6 Miscellaneous
--------------------

accept-and-hold (ESC-A ESC-a) (unbound) (unbound)
     Push the contents of the buffer on the buffer stack and execute it.

accept-and-infer-next-history
     Execute the contents of the buffer.  Then search the history list
     for a line matching the current one and push the event following
     onto the buffer stack.

accept-line (^J ^M) (^J ^M) (^J ^M)
     Finish editing the buffer.  Normally this causes the buffer to be
     executed as a shell command.

accept-line-and-down-history (^O) (unbound) (unbound)
     Execute the current line, and push the next history event on the
     buffer stack.

auto-suffix-remove
     If the previous action added a suffix (space, slash, etc.)  to the
     word on the command line, remove it.  Otherwise do nothing.
     Removing the suffix ends any active menu completion or menu
     selection.

     This widget is intended to be called from user-defined widgets to
     enforce a desired suffix-removal behavior.

auto-suffix-retain
     If the previous action added a suffix (space, slash, etc.)  to the
     word on the command line, force it to be preserved.  Otherwise do
     nothing.  Retaining the suffix ends any active menu completion or
     menu selection.

     This widget is intended to be called from user-defined widgets to
     enforce a desired suffix-preservation behavior.

beep
     Beep, unless the BEEP option is unset.

bracketed-paste (^[[200~) (^[[200~) (^[[200~)
     This widget is invoked when text is pasted to the terminal
     emulator.  It is not intended to be bound to actual keys but
     instead to the special sequence generated by the terminal emulator
     when text is pasted.

     When invoked interactively, the pasted text is inserted to the
     buffer and placed in the cutbuffer.  If a numeric argument is
     given, shell quoting will be applied to the pasted text before it
     is inserted.

     When a named buffer is specified with vi-set-buffer ("x), the
     pasted text is stored in that named buffer but not inserted.

     When called from a widget function as 'bracketed-paste NAME', the
     pasted text is assigned to the variable NAME and no other
     processing is done.

     See also the zle_bracketed_paste parameter.

vi-cmd-mode (^X^V) (unbound) (^[)
     Enter command mode; that is, select the 'vicmd' keymap.  Yes, this
     is bound by default in emacs mode.

vi-caps-lock-panic
     Hang until any lowercase key is pressed.  This is for vi users
     without the mental capacity to keep track of their caps lock key
     (like the author).

clear-screen (^L ESC-^L) (^L) (^L)
     Clear the screen and redraw the prompt.

deactivate-region
     Make the current region inactive.  This disables vim-style visual
     selection mode if it is active.

describe-key-briefly
     Reads a key sequence, then prints the function bound to that
     sequence.

exchange-point-and-mark (^X^X) (unbound) (unbound)
     Exchange the cursor position (point) with the position of the mark.
     Unless a negative numeric argument is given, the region between
     point and mark is activated so that it can be highlighted.  If a
     zero numeric argument is given, the region is activated but point
     and mark are not swapped.

execute-named-cmd (ESC-x) (:) (unbound)
     Read the name of an editor command and execute it.  Aliasing this
     widget with 'zle -A' or replacing it with 'zle -N' has no effect
     when interpreting key bindings, but 'zle execute-named-cmd' will
     invoke such an alias or replacement.

     A restricted set of editing functions is available in the
     mini-buffer.  Keys are looked up in the special command keymap, and
     if not found there in the main keymap.  An interrupt signal, as
     defined by the stty setting, will abort the function.  Note that
     the following always perform the same task within the
     executed-named-cmd environment and cannot be replaced by user
     defined widgets, nor can the set of functions be extended.  The
     allowed functions are: backward-delete-char,
     vi-backward-delete-char, clear-screen, redisplay, quoted-insert,
     vi-quoted-insert, backward-kill-word, vi-backward-kill-word,
     kill-whole-line, vi-kill-line, backward-kill-line, list-choices,
     delete-char-or-list, complete-word, accept-line, expand-or-complete
     and expand-or-complete-prefix.

     kill-region kills the last word, and vi-cmd-mode is treated the
     same as accept-line.  The space and tab characters, if not bound to
     one of these functions, will complete the name and then list the
     possibilities if the AUTO_LIST option is set.  Any other character
     that is not bound to self-insert or self-insert-unmeta will beep
     and be ignored.  The bindings of the current insert mode will be
     used.

     Currently this command may not be redefined or called by name.

execute-last-named-cmd (ESC-z) (unbound) (unbound)
     Redo the last function executed with execute-named-cmd.

     Like execute-named-cmd, this command may not be redefined, but it
     may be called by name.

get-line (ESC-G ESC-g) (unbound) (unbound)
     Pop the top line off the buffer stack and insert it at the cursor
     position.

pound-insert (unbound) (#) (unbound)
     If there is no # character at the beginning of the buffer, add one
     to the beginning of each line.  If there is one, remove a # from
     each line that has one.  In either case, accept the current line.
     The INTERACTIVE_COMMENTS option must be set for this to have any
     usefulness.

vi-pound-insert
     If there is no # character at the beginning of the current line,
     add one.  If there is one, remove it.  The INTERACTIVE_COMMENTS
     option must be set for this to have any usefulness.

push-input
     Push the entire current multiline construct onto the buffer stack
     and return to the top-level (PS1) prompt.  If the current parser
     construct is only a single line, this is exactly like push-line.
     Next time the editor starts up or is popped with get-line, the
     construct will be popped off the top of the buffer stack and loaded
     into the editing buffer.

push-line (^Q ESC-Q ESC-q) (unbound) (unbound)
     Push the current buffer onto the buffer stack and clear the buffer.
     Next time the editor starts up, the buffer will be popped off the
     top of the buffer stack and loaded into the editing buffer.

push-line-or-edit
     At the top-level (PS1) prompt, equivalent to push-line.  At a
     secondary (PS2) prompt, move the entire current multiline construct
     into the editor buffer.  The latter is equivalent to push-input
     followed by get-line.

read-command
     Only useful from a user-defined widget.  A keystroke is read just
     as in normal operation, but instead of the command being executed
     the name of the command that would be executed is stored in the
     shell parameter REPLY.  This can be used as the argument of a
     future zle command.  If the key sequence is not bound, status 1 is
     returned; typically, however, REPLY is set to undefined-key to
     indicate a useless key sequence.

recursive-edit
     Only useful from a user-defined widget.  At this point in the
     function, the editor regains control until one of the standard
     widgets which would normally cause zle to exit (typically an
     accept-line caused by hitting the return key) is executed.
     Instead, control returns to the user-defined widget.  The status
     returned is non-zero if the return was caused by an error, but the
     function still continues executing and hence may tidy up.  This
     makes it safe for the user-defined widget to alter the command line
     or key bindings temporarily.

     The following widget, caps-lock, serves as an example.

          self-insert-ucase() {
            LBUFFER+=${(U)KEYS[-1]}
          }

          integer stat

          zle -N self-insert self-insert-ucase
          zle -A caps-lock save-caps-lock
          zle -A accept-line caps-lock

          zle recursive-edit
          stat=$?

          zle -A .self-insert self-insert
          zle -A save-caps-lock caps-lock
          zle -D save-caps-lock

          (( stat )) && zle send-break

          return $stat

     This causes typed letters to be inserted capitalised until either
     accept-line (i.e.  typically the return key) is typed or the
     caps-lock widget is invoked again; the later is handled by saving
     the old definition of caps-lock as save-caps-lock and then
     rebinding it to invoke accept-line.  Note that an error from the
     recursive edit is detected as a non-zero return status and
     propagated by using the send-break widget.

redisplay (unbound) (^R) (^R)
     Redisplays the edit buffer.

reset-prompt (unbound) (unbound) (unbound)
     Force the prompts on both the left and right of the screen to be
     re-expanded, then redisplay the edit buffer.  This reflects changes
     both to the prompt variables themselves and changes in the
     expansion of the values (for example, changes in time or directory,
     or changes to the value of variables referred to by the prompt).

     Otherwise, the prompt is only expanded each time zle starts, and
     when the display has been interrupted by output from another part
     of the shell (such as a job notification) which causes the command
     line to be reprinted.

     reset-prompt doesn't alter the special parameter LASTWIDGET.

send-break (^G ESC-^G) (unbound) (unbound)
     Abort the current editor function, e.g.  execute-named-command, or
     the editor itself, e.g.  if you are in vared.  Otherwise abort the
     parsing of the current line; in this case the aborted line is
     available in the shell variable ZLE_LINE_ABORTED.  If the editor is
     aborted from within vared, the variable ZLE_VARED_ABORTED is set.

run-help (ESC-H ESC-h) (unbound) (unbound)
     Push the buffer onto the buffer stack, and execute the command
     'run-help CMD', where CMD is the current command.  run-help is
     normally aliased to man.

vi-set-buffer (unbound) (") (unbound)
     Specify a buffer to be used in the following command.  There are 37
     buffers that can be specified: the 26 'named' buffers "a to "z, the
     'yank' buffer "0, the nine 'queued' buffers "1 to "9 and the 'black
     hole' buffer "_.  The named buffers can also be specified as "A to
     "Z.

     When a buffer is specified for a cut, change or yank command, the
     text concerned replaces the previous contents of the specified
     buffer.  If a named buffer is specified using a capital, the newly
     cut text is appended to the buffer instead of overwriting it.  When
     using the "_ buffer, nothing happens.  This can be useful for
     deleting text without affecting any buffers.

     If no buffer is specified for a cut or change command, "1 is used,
     and the contents of "1 to "8 are each shifted along one buffer; the
     contents of "9 is lost.  If no buffer is specified for a yank
     command, "0 is used.  Finally, a paste command without a specified
     buffer will paste the text from the most recent command regardless
     of any buffer that might have been used with that command.

     When called from a widget function by the zle command, the buffer
     can optionally be specified with an argument.  For example,

          zle vi-set-buffer A

vi-set-mark (unbound) (m) (unbound)
     Set the specified mark at the cursor position.

set-mark-command (^@) (unbound) (unbound)
     Set the mark at the cursor position.  If called with a negative
     numeric argument, do not set the mark but deactivate the region so
     that it is no longer highlighted (it is still usable for other
     purposes).  Otherwise the region is marked as active.

spell-word (ESC-$ ESC-S ESC-s) (unbound) (unbound)
     Attempt spelling correction on the current word.

split-undo
     Breaks the undo sequence at the current change.  This is useful in
     vi mode as changes made in insert mode are coalesced on entering
     command mode.  Similarly, undo will normally revert as one all the
     changes made by a user-defined widget.

undefined-key
     This command is executed when a key sequence that is not bound to
     any command is typed.  By default it beeps.

undo (^_ ^Xu ^X^U) (u) (unbound)
     Incrementally undo the last text modification.  When called from a
     user-defined widget, takes an optional argument indicating a
     previous state of the undo history as returned by the
     UNDO_CHANGE_NO variable; modifications are undone until that state
     is reached, subject to any limit imposed by the UNDO_LIMIT_NO
     variable.

     Note that when invoked from vi command mode, the full prior change
     made in insert mode is reverted, the changes having been merged
     when command mode was selected.

redo (unbound) (^R) (unbound)
     Incrementally redo undone text modifications.

vi-undo-change (unbound) (unbound) (unbound)
     Undo the last text modification.  If repeated, redo the
     modification.

visual-mode (unbound) (v) (unbound)
     Toggle vim-style visual selection mode.  If line-wise visual mode
     is currently enabled then it is changed to being character-wise.
     If used following an operator, it forces the subsequent movement
     command to be treated as a character-wise movement.

visual-line-mode (unbound) (V) (unbound)
     Toggle vim-style line-wise visual selection mode.  If
     character-wise visual mode is currently enabled then it is changed
     to being line-wise.  If used following an operator, it forces the
     subsequent movement command to be treated as a line-wise movement.

what-cursor-position (^X=) (ga) (unbound)
     Print the character under the cursor, its code as an octal, decimal
     and hexadecimal number, the current cursor position within the
     buffer and the column of the cursor in the current line.

where-is
     Read the name of an editor command and print the listing of key
     sequences that invoke the specified command.  A restricted set of
     editing functions is available in the mini-buffer.  Keys are looked
     up in the special command keymap, and if not found there in the
     main keymap.

which-command (ESC-?) (unbound) (unbound)
     Push the buffer onto the buffer stack, and execute the command
     'which-command CMD'.  where CMD is the current command.
     which-command is normally aliased to whence.

vi-digit-or-beginning-of-line (unbound) (0) (unbound)
     If the last command executed was a digit as part of an argument,
     continue the argument.  Otherwise, execute vi-beginning-of-line.


File: zsh.info,  Node: Text Objects,  Prev: Miscellaneous,  Up: Standard Widgets

18.6.7 Text Objects
-------------------

Text objects are commands that can be used to select a block of text
according to some criteria.  They are a feature of the vim text editor
and so are primarily intended for use with vi operators or from visual
selection mode.  However, they can also be used from vi-insert or emacs
mode.  Key bindings listed below apply to the viopp and visual keymaps.

select-a-blank-word (aW)
     Select a word including adjacent blanks, where a word is defined as
     a series of non-blank characters.  With a numeric argument,
     multiple words will be selected.

select-a-shell-word (aa)
     Select the current command argument applying the normal rules for
     quoting.

select-a-word (aw)
     Select a word including adjacent blanks, using the normal vi-style
     word definition.  With a numeric argument, multiple words will be
     selected.

select-in-blank-word (iW)
     Select a word, where a word is defined as a series of non-blank
     characters.  With a numeric argument, multiple words will be
     selected.

select-in-shell-word (ia)
     Select the current command argument applying the normal rules for
     quoting.  If the argument begins and ends with matching quote
     characters, these are not included in the selection.

select-in-word (iw)
     Select a word, using the normal vi-style word definition.  With a
     numeric argument, multiple words will be selected.


File: zsh.info,  Node: Character Highlighting,  Prev: Standard Widgets,  Up: Zsh Line Editor

18.7 Character Highlighting
===========================

The line editor has the ability to highlight characters or regions of
the line that have a particular significance.  This is controlled by the
array parameter zle_highlight, if it has been set by the user.

If the parameter contains the single entry none all highlighting is
turned off.  Note the parameter is still expected to be an array.

Otherwise each entry of the array should consist of a word indicating a
context for highlighting, then a colon, then a comma-separated list of
the types of highlighting to apply in that context.

The contexts available for highlighting are the following:

default
     Any text within the command line not affected by any other
     highlighting.  Text outside the editable area of the command line
     is not affected.

isearch
     When one of the incremental history search widgets is active, the
     area of the command line matched by the search string or pattern.

region
     The currently selected text.  In emacs terminology, this is
     referred to as the region and is bounded by the cursor (point) and
     the mark.  The region is only highlighted if it is active, which is
     the case after the mark is modified with set-mark-command or
     exchange-point-and-mark.  Note that whether or not the region is
     active has no effect on its use within emacs style widgets, it
     simply determines whether it is highlighted.  In vi mode, the
     region corresponds to selected text in visual mode.

special
     Individual characters that have no direct printable representation
     but are shown in a special manner by the line editor.  These
     characters are described below.

suffix
     This context is used in completion for characters that are marked
     as suffixes that will be removed if the completion ends at that
     point, the most obvious example being a slash (/) after a directory
     name.  Note that suffix removal is configurable; the circumstances
     under which the suffix will be removed may differ for different
     completions.

paste
     Following a command to paste text, the characters that were
     inserted.

When region_highlight is set, the contexts that describe a region --
isearch, region, suffix, and paste -- are applied first, then
region_highlight is applied, then the remaining zle_highlight contexts
are applied.  If a particular character is affected by multiple
specifications, the last specification wins.

zle_highlight may contain additional fields for controlling how terminal
sequences to change colours are output.  Each of the following is
followed by a colon and a string in the same form as for key bindings.
This will not be necessary for the vast majority of terminals as the
defaults shown in parentheses are widely used.

fg_start_code (\e[3)
     The start of the escape sequence for the foreground colour.  This
     is followed by one to three ASCII digits representing the colour.
     Only used for palette colors, i.e.  not 24-bit colors specified via
     a color triplet.

fg_default_code (9)
     The number to use instead of the colour to reset the default
     foreground colour.

fg_end_code (m)
     The end of the escape sequence for the foreground colour.

bg_start_code (\e[4)
     The start of the escape sequence for the background colour.  See
     fg_start_code above.

bg_default_code (9)
     The number to use instead of the colour to reset the default
     background colour.

bg_end_code (m)
     The end of the escape sequence for the background colour.

The available types of highlighting are the following.  Note that not
all types of highlighting are available on all terminals:

none
     No highlighting is applied to the given context.  It is not useful
     for this to appear with other types of highlighting; it is used to
     override a default.

fg=COLOUR
     The foreground colour should be set to COLOUR, a decimal integer,
     the name of one of the eight most widely-supported colours or as a
     '#' followed by an RGB triplet in hexadecimal format.

     Not all terminals support this and, of those that do, not all
     provide facilities to test the support, hence the user should
     decide based on the terminal type.  Most terminals support the
     colours black, red, green, yellow, blue, magenta, cyan and white,
     which can be set by name.  In addition.  default may be used to set
     the terminal's default foreground colour.  Abbreviations are
     allowed; b or bl selects black.  Some terminals may generate
     additional colours if the bold attribute is also present.

     On recent terminals and on systems with an up-to-date terminal
     database the number of colours supported may be tested by the
     command 'echotc Co'; if this succeeds, it indicates a limit on the
     number of colours which will be enforced by the line editor.  The
     number of colours is in any case limited to 256 (i.e.  the range 0
     to 255).

     Some modern terminal emulators have support for 24-bit true colour
     (16 million colours).  In this case, the hex triplet format can be
     used.  This consists of a '#' followed by either a three or six
     digit hexadecimal number describing the red, green and blue
     components of the colour.  Hex triplets can also be used with 88
     and 256 colour terminals via the zsh/nearcolor module (see *note
     The zsh/nearcolor Module::).

     Colour is also known as color.

bg=COLOUR
     The background colour should be set to COLOUR.  This works
     similarly to the foreground colour, except the background is not
     usually affected by the bold attribute.

bold
     The characters in the given context are shown in a bold font.  Not
     all terminals distinguish bold fonts.

standout
     The characters in the given context are shown in the terminal's
     standout mode.  The actual effect is specific to the terminal; on
     many terminals it is inverse video.  On some such terminals, where
     the cursor does not blink it appears with standout mode negated,
     making it less than clear where the cursor actually is.  On such
     terminals one of the other effects may be preferable for
     highlighting the region and matched search string.

underline
     The characters in the given context are shown underlined.  Some
     terminals show the foreground in a different colour instead; in
     this case whitespace will not be highlighted.

The characters described above as 'special' are as follows.  The
formatting described here is used irrespective of whether the characters
are highlighted:

ASCII control characters
     Control characters in the ASCII range are shown as '^' followed by
     the base character.

Unprintable multibyte characters
     This item applies to control characters not in the ASCII range,
     plus other characters as follows.  If the MULTIBYTE option is in
     effect, multibyte characters not in the ASCII character set that
     are reported as having zero width are treated as combining
     characters when the option COMBINING_CHARS is on.  If the option is
     off, or if a character appears where a combining character is not
     valid, the character is treated as unprintable.

     Unprintable multibyte characters are shown as a hexadecimal number
     between angle brackets.  The number is the code point of the
     character in the wide character set; this may or may not be
     Unicode, depending on the operating system.

Invalid multibyte characters
     If the MULTIBYTE option is in effect, any sequence of one or more
     bytes that does not form a valid character in the current character
     set is treated as a series of bytes each shown as a special
     character.  This case can be distinguished from other unprintable
     characters as the bytes are represented as two hexadecimal digits
     between angle brackets, as distinct from the four or eight digits
     that are used for unprintable characters that are nonetheless valid
     in the current character set.

     Not all systems support this: for it to work, the system's
     representation of wide characters must be code values from the
     Universal Character Set, as defined by IS0 10646 (also known as
     Unicode).

Wrapped double-width characters
     When a double-width character appears in the final column of a
     line, it is instead shown on the next line.  The empty space left
     in the original position is highlighted as a special character.

If zle_highlight is not set or no value applies to a particular context,
the defaults applied are equivalent to

     zle_highlight=(region:standout special:standout
     suffix:bold isearch:underline paste:standout)

i.e.  both the region and special characters are shown in standout mode.

Within widgets, arbitrary regions may be highlighted by setting the
special array parameter region_highlight; see *note Zle Widgets::.


File: zsh.info,  Node: Completion Widgets,  Next: Completion System,  Prev: Zsh Line Editor,  Up: Top

19 Completion Widgets
*********************

19.1 Description
================

The shell's programmable completion mechanism can be manipulated in two
ways; here the low-level features supporting the newer, function-based
mechanism are defined.  A complete set of shell functions based on these
features is described in the next chapter, *note Completion System::,
and users with no interest in adding to that system (or, potentially,
writing their own -- see dictionary entry for 'hubris') should skip the
current section.  The older system based on the compctl builtin command
is described in *note Completion Using compctl::.

Completion widgets are defined by the -C option to the zle builtin
command provided by the zsh/zle module (see *note The zsh/zle Module::).
For example,

     zle -C complete expand-or-complete completer

defines a widget named 'complete'.  The second argument is the name of
any of the builtin widgets that handle completions: complete-word,
expand-or-complete, expand-or-complete-prefix, menu-complete,
menu-expand-or-complete, reverse-menu-complete, list-choices, or
delete-char-or-list.  Note that this will still work even if the widget
in question has been re-bound.

When this newly defined widget is bound to a key using the bindkey
builtin command defined in the zsh/zle module (*note Zsh Line Editor::),
typing that key will call the shell function 'completer'.  This function
is responsible for generating completion matches using the builtins
described below.  As with other ZLE widgets, the function is called with
its standard input closed.

Once the function returns, the completion code takes over control again
and treats the matches in the same manner as the specified builtin
widget, in this case expand-or-complete.

* Menu:

* Completion Special Parameters::
* Completion Builtin Commands::
* Completion Condition Codes::
* Completion Matching Control::
* Completion Widget Example::


File: zsh.info,  Node: Completion Special Parameters,  Next: Completion Builtin Commands,  Up: Completion Widgets

19.2 Completion Special Parameters
==================================

The parameters ZLE_REMOVE_SUFFIX_CHARS and ZLE_SPACE_SUFFIX_CHARS are
used by the completion mechanism, but are not special.  See *note
Parameters Used By The Shell::.

Inside completion widgets, and any functions called from them, some
parameters have special meaning; outside these functions they are not
special to the shell in any way.  These parameters are used to pass
information between the completion code and the completion widget.  Some
of the builtin commands and the condition codes use or change the
current values of these parameters.  Any existing values will be hidden
during execution of completion widgets; except for compstate, the
parameters are reset on each function exit (including nested function
calls from within the completion widget) to the values they had when the
function was entered.

CURRENT
     This is the number of the current word, i.e.  the word the cursor
     is currently on in the words array.  Note that this value is only
     correct if the ksharrays option is not set.

IPREFIX
     Initially this will be set to the empty string.  This parameter
     functions like PREFIX; it contains a string which precedes the one
     in PREFIX and is not considered part of the list of matches.
     Typically, a string is transferred from the beginning of PREFIX to
     the end of IPREFIX, for example:

          IPREFIX=${PREFIX%%\=*}=
          PREFIX=${PREFIX#*=}

     causes the part of the prefix up to and including the first equal
     sign not to be treated as part of a matched string.  This can be
     done automatically by the compset builtin, see below.

ISUFFIX
     As IPREFIX, but for a suffix that should not be considered part of
     the matches; note that the ISUFFIX string follows the SUFFIX
     string.

PREFIX
     Initially this will be set to the part of the current word from the
     beginning of the word up to the position of the cursor; it may be
     altered to give a common prefix for all matches.

QIPREFIX
     This parameter is read-only and contains the quoted string up to
     the word being completed.  E.g.  when completing '"foo', this
     parameter contains the double quote.  If the -q option of compset
     is used (see below), and the original string was '"foo bar' with
     the cursor on the 'bar', this parameter contains '"foo '.

QISUFFIX
     Like QIPREFIX, but containing the suffix.

SUFFIX
     Initially this will be set to the part of the current word from the
     cursor position to the end; it may be altered to give a common
     suffix for all matches.  It is most useful when the option
     COMPLETE_IN_WORD is set, as otherwise the whole word on the command
     line is treated as a prefix.

compstate
     This is an associative array with various keys and values that the
     completion code uses to exchange information with the completion
     widget.  The keys are:

     all_quotes
          The -q option of the compset builtin command (see below)
          allows a quoted string to be broken into separate words; if
          the cursor is on one of those words, that word will be
          completed, possibly invoking 'compset -q' recursively.  With
          this key it is possible to test the types of quoted strings
          which are currently broken into parts in this fashion.  Its
          value contains one character for each quoting level.  The
          characters are a single quote or a double quote for strings
          quoted with these characters, a dollars sign for strings
          quoted with $'...' and a backslash for strings not starting
          with a quote character.  The first character in the value
          always corresponds to the innermost quoting level.

     context
          This will be set by the completion code to the overall context
          in which completion is attempted.  Possible values are:

          array_value
               when completing inside the value of an array parameter
               assignment; in this case the words array contains the
               words inside the parentheses.

          brace_parameter
               when completing the name of a parameter in a parameter
               expansion beginning with ${.  This context will also be
               set when completing parameter flags following ${(; the
               full command line argument is presented and the handler
               must test the value to be completed to ascertain that
               this is the case.

          assign_parameter
               when completing the name of a parameter in a parameter
               assignment.

          command
               when completing for a normal command (either in command
               position or for an argument of the command).

          condition
               when completing inside a '[[...]]'  conditional
               expression; in this case the words array contains only
               the words inside the conditional expression.

          math
               when completing in a mathematical environment such as a
               '((...))'  construct.

          parameter
               when completing the name of a parameter in a parameter
               expansion beginning with $ but not ${.

          redirect
               when completing after a redirection operator.

          subscript
               when completing inside a parameter subscript.

          value
               when completing the value of a parameter assignment.

     exact
          Controls the behaviour when the REC_EXACT option is set.  It
          will be set to accept if an exact match would be accepted, and
          will be unset otherwise.

          If it was set when at least one match equal to the string on
          the line was generated, the match is accepted.

     exact_string
          The string of an exact match if one was found, otherwise
          unset.

     ignored
          The number of completions that were ignored because they
          matched one of the patterns given with the -F option to the
          compadd builtin command.

     insert
          This controls the manner in which a match is inserted into the
          command line.  On entry to the widget function, if it is unset
          the command line is not to be changed; if set to unambiguous,
          any prefix common to all matches is to be inserted; if set to
          automenu-unambiguous, the common prefix is to be inserted and
          the next invocation of the completion code may start menu
          completion (due to the AUTO_MENU option being set); if set to
          menu or automenu menu completion will be started for the
          matches currently generated (in the latter case this will
          happen because the AUTO_MENU is set).  The value may also
          contain the string 'tab' when the completion code would
          normally not really do completion, but only insert the TAB
          character.

          On exit it may be set to any of the values above (where
          setting it to the empty string is the same as unsetting it),
          or to a number, in which case the match whose number is given
          will be inserted into the command line.  Negative numbers
          count backward from the last match (with '-1' selecting the
          last match) and out-of-range values are wrapped around, so
          that a value of zero selects the last match and a value one
          more than the maximum selects the first.  Unless the value of
          this key ends in a space, the match is inserted as in a menu
          completion, i.e.  without automatically appending a space.

          Both menu and automenu may also specify the number of the
          match to insert, given after a colon.  For example, 'menu:2'
          says to start menu completion, beginning with the second
          match.

          Note that a value containing the substring 'tab' makes the
          matches generated be ignored and only the TAB be inserted.

          Finally, it may also be set to all, which makes all matches
          generated be inserted into the line.

     insert_positions
          When the completion system inserts an unambiguous string into
          the line, there may be multiple places where characters are
          missing or where the character inserted differs from at least
          one match.  The value of this key contains a colon separated
          list of all these positions, as indexes into the command line.

     last_prompt
          If this is set to a non-empty string for every match added,
          the completion code will move the cursor back to the previous
          prompt after the list of completions has been displayed.
          Initially this is set or unset according to the
          ALWAYS_LAST_PROMPT option.

     list
          This controls whether or how the list of matches will be
          displayed.  If it is unset or empty they will never be listed;
          if its value begins with list, they will always be listed; if
          it begins with autolist or ambiguous, they will be listed when
          the AUTO_LIST or LIST_AMBIGUOUS options respectively would
          normally cause them to be.

          If the substring force appears in the value, this makes the
          list be shown even if there is only one match.  Normally, the
          list would be shown only if there are at least two matches.

          The value contains the substring packed if the LIST_PACKED
          option is set.  If this substring is given for all matches
          added to a group, this group will show the LIST_PACKED
          behavior.  The same is done for the LIST_ROWS_FIRST option
          with the substring rows.

          Finally, if the value contains the string explanations, only
          the explanation strings, if any, will be listed and if it
          contains messages, only the messages (added with the -x option
          of compadd) will be listed.  If it contains both explanations
          and messages both kinds of explanation strings will be listed.
          It will be set appropriately on entry to a completion widget
          and may be changed there.

     list_lines
          This gives the number of lines that are needed to display the
          full list of completions.  Note that to calculate the total
          number of lines to display you need to add the number of lines
          needed for the command line to this value, this is available
          as the value of the BUFFERLINES special parameter.

     list_max
          Initially this is set to the value of the LISTMAX parameter.
          It may be set to any other value; when the widget exits this
          value will be used in the same way as the value of LISTMAX.

     nmatches
          The number of matches added by the completion code so far.

     old_insert
          On entry to the widget this will be set to the number of the
          match of an old list of completions that is currently inserted
          into the command line.  If no match has been inserted, this is
          unset.

          As with old_list, the value of this key will only be used if
          it is the string keep.  If it was set to this value by the
          widget and there was an old match inserted into the command
          line, this match will be kept and if the value of the insert
          key specifies that another match should be inserted, this will
          be inserted after the old one.

     old_list
          This is set to yes if there is still a valid list of
          completions from a previous completion at the time the widget
          is invoked.  This will usually be the case if and only if the
          previous editing operation was a completion widget or one of
          the builtin completion functions.  If there is a valid list
          and it is also currently shown on the screen, the value of
          this key is shown.

          After the widget has exited the value of this key is only used
          if it was set to keep.  In this case the completion code will
          continue to use this old list.  If the widget generated new
          matches, they will not be used.

     parameter
          The name of the parameter when completing in a subscript or in
          the value of a parameter assignment.

     pattern_insert
          Normally this is set to menu, which specifies that menu
          completion will be used whenever a set of matches was
          generated using pattern_match (see below).  If it is set to
          any other non-empty string by the user and menu completion is
          not selected by other option settings, the code will instead
          insert any common prefix for the generated matches as with
          normal completion.

     pattern_match
          Locally controls the behaviour given by the GLOB_COMPLETE
          option.  Initially it is set to '*' if and only if the option
          is set.  The completion widget may set it to this value, to an
          empty string (which has the same effect as unsetting it), or
          to any other non-empty string.  If it is non-empty, unquoted
          metacharacters on the command line will be treated as
          patterns; if it is '*', then additionally a wildcard '*' is
          assumed at the cursor position; if it is empty or unset,
          metacharacters will be treated literally.

          Note that the match specifications given to the compadd
          builtin command are not used if this is set to a non-empty
          string.

     quote
          When completing inside quotes, this contains the quotation
          character (i.e.  either a single quote, a double quote, or a
          backtick).  Otherwise it is unset.

     quoting
          When completing inside single quotes, this is set to the
          string single; inside double quotes, the string double; inside
          backticks, the string backtick.  Otherwise it is unset.

     redirect
          The redirection operator when completing in a redirection
          position, i.e.  one of <, >, etc.

     restore
          This is set to auto before a function is entered, which forces
          the special parameters mentioned above (words, CURRENT,
          PREFIX, IPREFIX, SUFFIX, and ISUFFIX) to be restored to their
          previous values when the function exits.  If a function unsets
          it or sets it to any other string, they will not be restored.

     to_end
          Specifies the occasions on which the cursor is moved to the
          end of a string when a match is inserted.  On entry to a
          widget function, it may be single if this will happen when a
          single unambiguous match was inserted or match if it will
          happen any time a match is inserted (for example, by menu
          completion; this is likely to be the effect of the
          ALWAYS_TO_END option).

          On exit, it may be set to single as above.  It may also be set
          to always, or to the empty string or unset; in those cases the
          cursor will be moved to the end of the string always or never
          respectively.  Any other string is treated as match.

     unambiguous
          This key is read-only and will always be set to the common
          (unambiguous) prefix the completion code has generated for all
          matches added so far.

     unambiguous_cursor
          This gives the position the cursor would be placed at if the
          common prefix in the unambiguous key were inserted, relative
          to the value of that key.  The cursor would be placed before
          the character whose index is given by this key.

     unambiguous_positions
          This contains all positions where characters in the
          unambiguous string are missing or where the character inserted
          differs from at least one of the matches.  The positions are
          given as indexes into the string given by the value of the
          unambiguous key.

     vared
          If completion is called while editing a line using the vared
          builtin, the value of this key is set to the name of the
          parameter given as an argument to vared.  This key is only set
          while a vared command is active.

words
     This array contains the words present on the command line currently
     being edited.


File: zsh.info,  Node: Completion Builtin Commands,  Next: Completion Condition Codes,  Prev: Completion Special Parameters,  Up: Completion Widgets

19.3 Completion Builtin Commands
================================

compadd [ -akqQfenUl12C ] [ -F ARRAY ]
        [-P PREFIX ] [ -S SUFFIX ]
        [-p HIDDEN-PREFIX ] [ -s HIDDEN-SUFFIX ]
        [-i IGNORED-PREFIX ] [ -I IGNORED-SUFFIX ]
        [-W FILE-PREFIX ] [ -d ARRAY ]
        [-J GROUP-NAME ] [ -X EXPLANATION ] [ -x MESSAGE ]
        [-V GROUP-NAME ] [ -o [ ORDER ] ]
        [-r REMOVE-CHARS ] [ -R REMOVE-FUNC ]
        [-D ARRAY ] [ -O ARRAY ] [ -A ARRAY ]
        [-E NUMBER ]
        [-M MATCH-SPEC ] [ -- ] [ COMPLETIONS ... ]

     This builtin command can be used to add matches directly and
     control all the information the completion code stores with each
     possible completion.  The return status is zero if at least one
     match was added and non-zero if no matches were added.

     The completion code breaks each match into seven fields in the
     order:

          <IPRE><APRE><HPRE><BODY><HSUF><ASUF><ISUF>

     The first field is an ignored prefix taken from the command line,
     the contents of the IPREFIX parameter plus the string given with
     the -i option.  With the -U option, only the string from the -i
     option is used.  The field <APRE> is an optional prefix string
     given with the -P option.  The <HPRE> field is a string that is
     considered part of the match but that should not be shown when
     listing completions, given with the -p option; for example,
     functions that do filename generation might specify a common path
     prefix this way.  <BODY> is the part of the match that should
     appear in the list of matches shown to the user.  The suffixes
     <HSUF>, <ASUF> and <ISUF> correspond to the prefixes <HPRE>, <APRE>
     and <IPRE> and are given by the options -s, -S and -I,
     respectively.

     The supported flags are:

     -P PREFIX
          This gives a string to be inserted before each match.  The
          string given is not considered as part of the match and any
          shell metacharacters in it will not be quoted when the string
          is inserted.

     -S SUFFIX
          Like -P, but gives a string to be inserted after each match.

     -p HIDDEN-PREFIX
          This gives a string that should be inserted before each match
          but that should not appear in the list of matches.  Unless the
          -U option is given, this string must be matched as part of the
          string on the command line.

     -s HIDDEN-SUFFIX
          Like '-p', but gives a string to insert after each match.

     -i IGNORED-PREFIX
          This gives a string to insert just before any string given
          with the '-P' option.  Without '-P' the string is inserted
          before the string given with '-p' or directly before each
          match.

     -I IGNORED-SUFFIX
          Like -i, but gives an ignored suffix.

     -a
          With this flag the COMPLETIONS are taken as names of arrays
          and the actual completions are their values.  If only some
          elements of the arrays are needed, the COMPLETIONS may also
          contain subscripts, as in 'foo[2,-1]'.

     -k
          With this flag the COMPLETIONS are taken as names of
          associative arrays and the actual completions are their keys.
          As for -a, the WORDS may also contain subscripts, as in
          'foo[(R)*bar*]'.

     -d ARRAY
          This adds per-completion display strings.  The ARRAY should
          contain one element per COMPLETION given.  The completion code
          will then display the first element instead of the first
          COMPLETION, and so on.  The ARRAY may be given as the name of
          an array parameter or directly as a space-separated list of
          words in parentheses.

          If there are fewer display strings than COMPLETIONS, the
          leftover COMPLETIONS will be displayed unchanged and if there
          are more display strings than COMPLETIONS, the leftover
          display strings will be silently ignored.

     -l
          This option only has an effect if used together with the -d
          option.  If it is given, the display strings are listed one
          per line, not arrayed in columns.

     -o [ ORDER ]
          This controls the order in which matches are sorted.  ORDER is
          a comma-separated list comprising the following possible
          values.  These values can be abbreviated to their initial two
          or three characters.  Note that the order forms part of the
          group name space so matches with different orderings will not
          be in the same group.

          match
               If given, the order of the output is determined by the
               match strings; otherwise it is determined by the display
               strings (i.e.  the strings given by the -d option).  This
               is the default if '-o' is specified but the ORDER
               argument is omitted.

          nosort
               This specifies that the COMPLETIONS are pre-sorted and
               their order should be preserved.  This value only makes
               sense alone and cannot be combined with any others.

          numeric
               If the matches include numbers, sort them numerically
               rather than lexicographically.

          reverse
               Arrange the matches backwards by reversing the sort
               ordering.

     -J GROUP-NAME
          Gives the name of the group that the matches should be stored
          in.

     -V GROUP-NAME
          Like -J but naming an unsorted group.  This option is
          identical to the combination of -J and -o nosort.

     -1
          If given together with the -V option, makes only consecutive
          duplicates in the group be removed.  If combined with the -J
          option, this has no visible effect.  Note that groups with and
          without this flag are in different name spaces.

     -2
          If given together with the -J or -V option, makes all
          duplicates be kept.  Again, groups with and without this flag
          are in different name spaces.

     -X EXPLANATION
          The EXPLANATION string will be printed with the list of
          matches, above the group currently selected.

          Within the EXPLANATION, the following sequences may be used to
          specify output attributes (see *note Prompt Expansion::):
          '%B', '%S', '%U', '%F', '%K' and their lower case
          counterparts, as well as '%{...%}'.  '%F', '%K' and '%{...%}'
          take arguments in the same form as prompt expansion.  (Note
          that the sequence '%G' is not available; an argument to '%{'
          should be used instead.)  The sequence '%%' produces a literal
          '%'.

          These sequences are most often employed by users when
          customising the format style (see *note Completion System::),
          but they must also be taken into account when writing
          completion functions, as passing descriptions with unescaped
          '%' characters to utility functions such as _arguments and
          _message may produce unexpected results.  If arbitrary text is
          to be passed in a description, it can be escaped using e.g.
          ${my_str//\%/%%}.

     -x MESSAGE
          Like -X, but the MESSAGE will be printed even if there are no
          matches in the group.

     -q
          The suffix given with -S will be automatically removed if the
          next character typed is a blank or does not insert anything,
          or if the suffix consists of only one character and the next
          character typed is the same character.

     -r REMOVE-CHARS
          This is a more versatile form of the -q option.  The suffix
          given with -S or the slash automatically added after
          completing directories will be automatically removed if the
          next character typed inserts one of the characters given in
          the REMOVE-CHARS.  This string is parsed as a characters class
          and understands the backslash sequences used by the print
          command.  For example, '-r "a-z\t"' removes the suffix if the
          next character typed inserts a lower case character or a TAB,
          and '-r "^0-9"' removes the suffix if the next character typed
          inserts anything but a digit.  One extra backslash sequence is
          understood in this string: '\-' stands for all characters that
          insert nothing.  Thus '-S "=" -q' is the same as '-S "=" -r "=
          \t\n\-"'.

          This option may also be used without the -S option; then any
          automatically added space will be removed when one of the
          characters in the list is typed.

     -R REMOVE-FUNC
          This is another form of the -r option.  When a match has been
          accepted and a suffix has been inserted, the function
          REMOVE-FUNC will be called after the next character typed.  It
          is passed the length of the suffix as an argument and can use
          the special parameters available in ordinary (non-completion)
          zle widgets (see *note Zsh Line Editor::) to analyse and
          modify the command line.

     -f
          If this flag is given, all of the matches built from the
          COMPLETIONS are marked as being the names of files.  They are
          not required to be actual filenames, but if they are, and the
          option LIST_TYPES is set, the characters describing the types
          of the files in the completion lists will be shown.  This also
          forces a slash to be added when the name of a directory is
          completed.

     -e
          This flag can be used to tell the completion code that the
          matches added are parameter names for a parameter expansion.
          This will make the AUTO_PARAM_SLASH and AUTO_PARAM_KEYS
          options be used for the matches.

     -W FILE-PREFIX
          This string is a pathname that will be prepended to each match
          together with any prefix specified by the -p option to form a
          complete filename for testing.  Hence it is only useful if
          combined with the -f flag, as the tests will not otherwise be
          performed.

     -F ARRAY
          Specifies an array containing patterns.  COMPLETIONS that
          match one of these patterns are ignored, that is, not
          considered to be matches.

          The ARRAY may be the name of an array parameter or a list of
          literal patterns enclosed in parentheses and quoted, as in '-F
          "(*?.o *?.h)"'.  If the name of an array is given, the
          elements of the array are taken as the patterns.

     -Q
          This flag instructs the completion code not to quote any
          metacharacters in the matches when inserting them into the
          command line.

     -M MATCH-SPEC
          This gives local match specifications as described below in
          *note Completion Matching Control::.  This option may be given
          more than once.  In this case all MATCH-SPECs given are
          concatenated with spaces between them to form the
          specification string to use.  Note that they will only be used
          if the -U option is not given.

     -n
          Specifies that matching COMPLETIONS are to be added to the set
          of matches, but are not to be listed to the user.

     -U
          If this flag is given, all COMPLETIONS are added to the set of
          matches and no matching will be done by the completion code.
          Normally this is used in functions that do the matching
          themselves.

     -O ARRAY
          If this option is given, the COMPLETIONS are _not_ added to
          the set of matches.  Instead, matching is done as usual and
          all of the COMPLETIONS that match will be stored in the array
          parameter whose name is given as ARRAY.

     -A ARRAY
          As the -O option, except that instead of those of the
          COMPLETIONS which match being stored in ARRAY, the strings
          generated internally by the completion code are stored.  For
          example, with a match specification of '-M "L:|no="', a
          current word of 'nof' and COMPLETIONS of 'foo', this option
          stores the string 'nofoo' in the array, whereas the -O option
          stores the 'foo' originally given.

     -D ARRAY
          As with -O, the COMPLETIONS are not added to the set of
          matches.  Instead, whenever the Nth COMPLETION does not match,
          the Nth element of the ARRAY is removed.  Elements for which
          the corresponding COMPLETION matches are retained.  This
          option can be used more than once to remove elements from
          multiple arrays.

     -C
          This option adds a special match which expands to all other
          matches when inserted into the line, even those that are added
          after this option is used.  Together with the -d option it is
          possible to specify a string that should be displayed in the
          list for this special match.  If no string is given, it will
          be shown as a string containing the strings that would be
          inserted for the other matches, truncated to the width of the
          screen.

     -E NUMBER
          This option adds NUMBER empty matches after matching
          COMPLETIONS have been added.  An empty match takes up space in
          completion listings but will never be inserted in the line and
          can't be selected with menu completion or menu selection.
          This makes empty matches only useful to format completion
          lists and to make explanatory string be shown in completion
          lists (since empty matches can be given display strings with
          the -d option).  And because all but one empty string would
          otherwise be removed, this option implies the -V and -2
          options (even if an explicit -J option is given).  This can be
          important to note as it affects the name space into which
          matches are added.

     -
     --
          This flag ends the list of flags and options.  All arguments
          after it will be taken as the COMPLETIONS even if they begin
          with hyphens.

     Except for the -M flag, if any of these flags is given more than
     once, the first one (and its argument) will be used.

compset -p NUMBER
compset -P [ NUMBER ] PATTERN
compset -s NUMBER
compset -S [ NUMBER ] PATTERN
compset -n BEGIN [ END ]
compset -N BEG-PAT [ END-PAT ]
compset -q
     This command simplifies modification of the special parameters,
     while its return status allows tests on them to be carried out.

     The options are:

     -p NUMBER
          If the value of the PREFIX parameter is at least NUMBER
          characters long, the first NUMBER characters are removed from
          it and appended to the contents of the IPREFIX parameter.

     -P [ NUMBER ] PATTERN
          If the value of the PREFIX parameter begins with anything that
          matches the PATTERN, the matched portion is removed from
          PREFIX and appended to IPREFIX.

          Without the optional NUMBER, the longest match is taken, but
          if NUMBER is given, anything up to the NUMBERth match is
          moved.  If the NUMBER is negative, the NUMBERth longest match
          is moved.  For example, if PREFIX contains the string 'a=b=c',
          then compset -P '*\=' will move the string 'a=b=' into the
          IPREFIX parameter, but compset -P 1 '*\=' will move only the
          string 'a='.

     -s NUMBER
          As -p, but transfer the last NUMBER characters from the value
          of SUFFIX to the front of the value of ISUFFIX.

     -S [ NUMBER ] PATTERN
          As -P, but match the last portion of SUFFIX and transfer the
          matched portion to the front of the value of ISUFFIX.

     -n BEGIN [ END ]
          If the current word position as specified by the parameter
          CURRENT is greater than or equal to BEGIN, anything up to the
          BEGINth word is removed from the words array and the value of
          the parameter CURRENT is decremented by BEGIN.

          If the optional END is given, the modification is done only if
          the current word position is also less than or equal to END.
          In this case, the words from position END onwards are also
          removed from the words array.

          Both BEGIN and END may be negative to count backwards from the
          last element of the words array.

     -N BEG-PAT [ END-PAT ]
          If one of the elements of the words array before the one at
          the index given by the value of the parameter CURRENT matches
          the pattern BEG-PAT, all elements up to and including the
          matching one are removed from the words array and the value of
          CURRENT is changed to point to the same word in the changed
          array.

          If the optional pattern END-PAT is also given, and there is an
          element in the words array matching this pattern, the
          parameters are modified only if the index of this word is
          higher than the one given by the CURRENT parameter (so that
          the matching word has to be after the cursor).  In this case,
          the words starting with the one matching end-pat are also
          removed from the words array.  If words contains no word
          matching END-PAT, the testing and modification is performed as
          if it were not given.

     -q
          The word currently being completed is split on spaces into
          separate words, respecting the usual shell quoting
          conventions.  The resulting words are stored in the words
          array, and CURRENT, PREFIX, SUFFIX, QIPREFIX, and QISUFFIX are
          modified to reflect the word part that is completed.

     In all the above cases the return status is zero if the test
     succeeded and the parameters were modified and non-zero otherwise.
     This allows one to use this builtin in tests such as:

          if compset -P '*\='; then ...

     This forces anything up to and including the last equal sign to be
     ignored by the completion code.

compcall [ -TD ]
     This allows the use of completions defined with the compctl builtin
     from within completion widgets.  The list of matches will be
     generated as if one of the non-widget completion functions
     (complete-word, etc.)  had been called, except that only compctls
     given for specific commands are used.  To force the code to try
     completions defined with the -T option of compctl and/or the
     default completion (whether defined by compctl -D or the builtin
     default) in the appropriate places, the -T and/or -D flags can be
     passed to compcall.

     The return status can be used to test if a matching compctl
     definition was found.  It is non-zero if a compctl was found and
     zero otherwise.

     Note that this builtin is defined by the zsh/compctl module.


File: zsh.info,  Node: Completion Condition Codes,  Next: Completion Matching Control,  Prev: Completion Builtin Commands,  Up: Completion Widgets

19.4 Completion Condition Codes
===============================

The following additional condition codes for use within the [[ ... ]]
construct are available in completion widgets.  These work on the
special parameters.  All of these tests can also be performed by the
compset builtin, but in the case of the condition codes the contents of
the special parameters are not modified.

-prefix [ NUMBER ] PATTERN
     true if the test for the -P option of compset would succeed.

-suffix [ NUMBER ] PATTERN
     true if the test for the -S option of compset would succeed.

-after BEG-PAT
     true if the test of the -N option with only the BEG-PAT given would
     succeed.

-between BEG-PAT END-PAT
     true if the test for the -N option with both patterns would
     succeed.


File: zsh.info,  Node: Completion Matching Control,  Next: Completion Widget Example,  Prev: Completion Condition Codes,  Up: Completion Widgets

19.5 Completion Matching Control
================================

When the user invokes completion, the current _word_ on the command line
(that is, the word the cursor is currently on) is used to generate a
_match pattern_.  Only those _completions_ that match the pattern are
offered to the user as _matches_.

The default match pattern is generated from the current word by either

   • appending a '*' (matching any number of characters in a completion)
     _or,_
   • if the shell option COMPLETE_IN_WORD is set, inserting a '*' at the
     cursor position.

This narrow pattern can be broadened selectively by passing a _match
specification_ to the compadd builtin command through its -M option (see
*note Completion Builtin Commands::).  A match specification consists of
one or more MATCHERS separated by whitespace.  Matchers in a match
specification are applied one at a time, from left to right.  Once all
matchers have been applied, completions are compared to the final match
pattern and non-matching ones are discarded.

   • Note that the -M option is ignored if the current word contains a
     glob pattern and the shell option GLOB_COMPLETE is set or if the
     pattern_match key of the special associative array compstate is set
     to a non-empty value (see *note Completion Special Parameters::).
   • Users of the *note Completion System:: should generally not use the
     -M option directly, but rather use the matcher-list and matcher
     styles (see the subsection _Standard Styles_ in *note Completion
     System Configuration::).

Each matcher consists of

   • a case-sensitive letter
   • a ':',
   • one or more patterns separated by pipes ('|'),
   • an equals sign ('='), and
   • another pattern.

The patterns before the '=' are used to match substrings of the current
word.  For each matched substring, the corresponding part of the match
pattern is broadened with the pattern after the '=', by means of a
logical OR.

Each pattern in a matcher cosists of either

   • the empty string or
   • a sequence of

        • literal characters (which may be quoted with a '\'),
        • question marks ('?'),
        • bracket expressions ('[...]'; see the subsection _Glob
          Operators_ in *note Filename Generation::), and/or
        • brace expressions (see below).

Other shell patterns are not allowed.

A brace expression, like a bracket expression, consists of a list of

   • literal characters,
   • ranges ('0-9'), and/or
   • character classes ('[:NAME:]').

However, they differ from each other as follows:

   • A brace expression is delimited by a pair of braces ('{...}').
   • Brace expressions do not support negations.  That is, an initial
     '!' or '^' has no special meaning and will be interpreted as a
     literal character.
   • When a character in the current word matches the Nth pattern in a
     brace expression, the corresponding part of the match pattern is
     broadened only with the Nth pattern of the brace expression on the
     other side of the '=', if there is one; if there is no brace
     expression on the other side, then this pattern is the empty
     string.  However, if either brace expression has more elements than
     the other, then the excess entries are simply ignored.  When
     comparing indexes, each literal character or character class counts
     as one element, but each range is instead expanded to the full list
     of literal characters it represents.  Additionally, if on _both_
     sides of the '=', the Nth pattern is '[:upper:]' or '[:lower:]',
     then these are expanded as ranges, too.

Note that, although the matching system does not yet handle multibyte
characters, this is likely to be a future extension.  Hence, using
'[:upper:]' and '[:lower:]' is recommended over 'A-Z' and 'a-z'.

Below are the different forms of matchers supported.  Each _uppercase_
form behaves exactly like its lowercase counterpart, but adds an
additional step _after_ the match pattern has filtered out non-matching
completions: Each of a match's substrings that was matched by a
subpattern from an uppercase matcher is replaced with the corresponding
substring of the current word.  However, patterns from _lowercase_
matchers have higher weight: If a substring of the current word was
matched by patterns from both a lowercase and an uppercase matcher, then
the lowercase matcher's pattern wins and the corresponding part of the
match is not modified.

Unless indicated otherwise, each example listed assumes COMPLETE_IN_WORD
to be unset (as it is by default).

m:WORD-PAT=MATCH-PAT
M:WORD-PAT=MATCH-PAT

     For each substring of the current word that matches WORD-PAT,
     broaden the corresponding part of the match pattern to additionally
     match MATCH-PAT.

     Examples:

          m:{[:lower:]}={[:upper:]} lets any lower case character in the
          current word be completed to itself or its uppercase
          counterpart.  So, the completions 'foo', 'FOO' and 'Foo' will
          are be considered matches for the word 'fo'.

          M:_= inserts every underscore from the current word into each
          match, in the same relative position, determined by matching
          the substrings around it.  So, given a completion 'foo', the
          word 'f_o' will be completed to the match 'f_oo', even though
          the latter was not present as a completion.

b:WORD-PAT=MATCH-PAT
B:WORD-PAT=MATCH-PAT
e:WORD-PAT=MATCH-PAT
E:WORD-PAT=MATCH-PAT

     For each consecutive substring at the b:eginning or e:nd of the
     current word that matches WORD-PAT, broaden the corresponding part
     of the match pattern to additionally match MATCH-PAT.

     Examples:

          'b:-=+' lets any number of minuses at the start of the current
          word be completed to a minus or a plus.

          'B:0=' adds all zeroes at the beginning of the current word to
          the beginning of each match.

l:|WORD-PAT=MATCH-PAT
L:|WORD-PAT=MATCH-PAT
r:WORD-PAT|=MATCH-PAT
R:WORD-PAT|=MATCH-PAT

     If there is a substring at the l:eft or r:ight edge of the current
     word that matches WORD-PAT, then broaden the corresponding part of
     the match pattern to additionally match MATCH-PAT.

     For each l:, L:, r: and R: matcher (including the ones below), the
     pattern MATCH-PAT may also be a '*'.  This matches any number of
     characters in a completion.

     Examples:

          'r:|=*' appends a '*' to the match pattern, even when
          COMPLETE_IN_WORD is set and the cursor is not at the end of
          the current word.

          If the current word starts with a minus, then 'L:|-=' will
          prepend it to each match.

l:ANCHOR|WORD-PAT=MATCH-PAT
L:ANCHOR|WORD-PAT=MATCH-PAT
r:WORD-PAT|ANCHOR=MATCH-PAT
R:WORD-PAT|ANCHOR=MATCH-PAT

     For each substring of the current word that matches WORD-PAT and
     has on its l:eft or r:ight another substring matching ANCHOR,
     broaden the corresponding part of the match pattern to additionally
     match MATCH-PAT.

     Note that these matchers (and the ones below) modify only what is
     matched by WORD-PAT; they do not change the matching behavior of
     what is matched by ANCHOR (or COANCHOR; see the matchers below).
     Thus, unless its corresponding part of the match pattern has been
     modified, the anchor in the current word has to match literally in
     each completion, just like any other substring of the current word.

     If a matcher includes at least one anchor (which includes the
     matchers with two anchors, below), then MATCH-PAT may also be '*'
     or '**'.  '*' can match any part of a completion that does not
     contain any substrings matching ANCHOR, whereas a '**' can match
     any part of a completion, period.  (Note that this is different
     from the behavior of '*' in the anchorless forms of 'l:' and 'r:'
     and and also different from '*' and '**' in glob expressions.)

     Examples:

          'r:|.=*' makes the completion 'comp.sources.unix' a match for
          the word '..u' -- but _not_ for the word '.u'.

          Given a completion '--foo', the matcher 'L:--|no-=' will
          complete the word '--no-' to the match '--no-foo'.

l:ANCHOR||COANCHOR=MATCH-PAT
L:ANCHOR||COANCHOR=MATCH-PAT
r:COANCHOR||ANCHOR=MATCH-PAT
R:COANCHOR||ANCHOR=MATCH-PAT

     For any two consecutive substrings of the current word that match
     ANCHOR and COANCHOR, in the order given, insert the pattern
     MATCH-PAT between their corresponding parts in the match pattern.

     Note that, unlike ANCHOR, the pattern COANCHOR does not change what
     '*' can match.

     Examples:

          'r:?||[[:upper:]]=*' will complete the current word 'fB' to
          'fooBar', but it will not complete it to 'fooHooBar' (because
          '*' here cannot match anything that includes a match for
          '[[:upper:]]), nor will it complete 'B' to 'fooBar' (because
          there is no character in the current word to match COANCHOR).

          Given the current word 'pass.n' and a completion
          'pass.byname', the matcher 'L:.||[[:alpha:]]=by' will produce
          the match 'pass.name'.

x:

     Ignore this matcher and all matchers to its right.

     This matcher is used to mark the end of a match specification.  In
     a single standalone list of matchers, this has no use, but where
     match specifications are concatenated, as is often the case when
     using the *note Completion System::, it can allow one match
     specification to override another.


File: zsh.info,  Node: Completion Widget Example,  Prev: Completion Matching Control,  Up: Completion Widgets

19.6 Completion Widget Example
==============================

The first step is to define the widget:

     zle -C complete complete-word complete-files

Then the widget can be bound to a key using the bindkey builtin command:

     bindkey '^X\t' complete

After that the shell function complete-files will be invoked after
typing control-X and TAB. The function should then generate the matches,
e.g.:

     complete-files () { compadd - * }

This function will complete files in the current directory matching the
current word.


File: zsh.info,  Node: Completion System,  Next: Completion Using compctl,  Prev: Completion Widgets,  Up: Top

20 Completion System
********************

20.1 Description
================

This describes the shell code for the 'new' completion system, referred
to as compsys.  It is written in shell functions based on the features
described in the previous chapter, *note Completion Widgets::.

The features are contextual, sensitive to the point at which completion
is started.  Many completions are already provided.  For this reason, a
user can perform a great many tasks without knowing any details beyond
how to initialize the system, which is described in *note
Initialization::.

The context that decides what completion is to be performed may be

   • an argument or option position: these describe the position on the
     command line at which completion is requested.  For example 'first
     argument to rmdir, the word being completed names a directory';

   • a special context, denoting an element in the shell's syntax.  For
     example 'a word in command position' or 'an array subscript'.

A full context specification contains other elements, as we shall
describe.

Besides commands names and contexts, the system employs two more
concepts, _styles_ and _tags_.  These provide ways for the user to
configure the system's behaviour.

Tags play a dual role.  They serve as a classification system for the
matches, typically indicating a class of object that the user may need
to distinguish.  For example, when completing arguments of the ls
command the user may prefer to try files before directories, so both of
these are tags.  They also appear as the rightmost element in a context
specification.

Styles modify various operations of the completion system, such as
output formatting, but also what kinds of completers are used (and in
what order), or which tags are examined.  Styles may accept arguments
and are manipulated using the zstyle command described in *note The
zsh/zutil Module::.

In summary, tags describe _what_ the completion objects are, and style
how they are to be completed.  At various points of execution, the
completion system checks what styles and/or tags are defined for the
current context, and uses that to modify its behavior.  The full
description of context handling, which determines how tags and other
elements of the context influence the behaviour of styles, is described
in *note Completion System Configuration::.

When a completion is requested, a dispatcher function is called; see the
description of _main_complete in the list of control functions below.
This dispatcher decides which function should be called to produce the
completions, and calls it.  The result is passed to one or more
_completers_, functions that implement individual completion strategies:
simple completion, error correction, completion with error correction,
menu selection, etc.

More generally, the shell functions contained in the completion system
are of two types:

   • those beginning 'comp' are to be called directly; there are only a
     few of these;

   • those beginning '_' are called by the completion code.  The shell
     functions of this set, which implement completion behaviour and may
     be bound to keystrokes, are referred to as 'widgets'.  These
     proliferate as new completions are required.

* Menu:

* Initialization::
* Completion System Configuration::
* Control Functions::
* Bindable Commands::
* Completion Functions::
* Completion Directories::
* Completion System Variables::


File: zsh.info,  Node: Initialization,  Next: Completion System Configuration,  Up: Completion System

20.2 Initialization
===================

If the system was installed completely, it should be enough to call the
shell function compinit from your initialization file; see the next
section.  However, the function compinstall can be run by a user to
configure various aspects of the completion system.

Usually, compinstall will insert code into .zshrc, although if that is
not writable it will save it in another file and tell you that file's
location.  Note that it is up to you to make sure that the lines added
to .zshrc are actually run; you may, for example, need to move them to
an earlier place in the file if .zshrc usually returns early.  So long
as you keep them all together (including the comment lines at the start
and finish), you can rerun compinstall and it will correctly locate and
modify these lines.  Note, however, that any code you add to this
section by hand is likely to be lost if you rerun compinstall, although
lines using the command 'zstyle' should be gracefully handled.

The new code will take effect next time you start the shell, or run
.zshrc by hand; there is also an option to make them take effect
immediately.  However, if compinstall has removed definitions, you will
need to restart the shell to see the changes.

To run compinstall you will need to make sure it is in a directory
mentioned in your fpath parameter, which should already be the case if
zsh was properly configured as long as your startup files do not remove
the appropriate directories from fpath.  Then it must be autoloaded
('autoload -U compinstall' is recommended).  You can abort the
installation any time you are being prompted for information, and your
.zshrc will not be altered at all; changes only take place right at the
end, where you are specifically asked for confirmation.

20.2.1 Use of compinit
----------------------

This section describes the use of compinit to initialize completion for
the current session when called directly; if you have run compinstall it
will be called automatically from your .zshrc.

To initialize the system, the function compinit should be in a directory
mentioned in the fpath parameter, and should be autoloaded ('autoload -U
compinit' is recommended), and then run simply as 'compinit'.  This will
define a few utility functions, arrange for all the necessary shell
functions to be autoloaded, and will then re-define all widgets that do
completion to use the new system.  If you use the menu-select widget,
which is part of the zsh/complist module, you should make sure that that
module is loaded before the call to compinit so that that widget is also
re-defined.  If completion styles (see below) are set up to perform
expansion as well as completion by default, and the TAB key is bound to
expand-or-complete, compinit will rebind it to complete-word; this is
necessary to use the correct form of expansion.

Should you need to use the original completion commands, you can still
bind keys to the old widgets by putting a '.' in front of the widget
name, e.g.  '.expand-or-complete'.

To speed up the running of compinit, it can be made to produce a dumped
configuration that will be read in on future invocations; this is the
default, but can be turned off by calling compinit with the option -D.
The dumped file is .zcompdump in the same directory as the startup files
(i.e.  $ZDOTDIR or $HOME); alternatively, an explicit file name can be
given by 'compinit -d DUMPFILE'.  The next invocation of compinit will
read the dumped file instead of performing a full initialization.

If the number of completion files changes, compinit will recognise this
and produce a new dump file.  However, if the name of a function or the
arguments in the first line of a #compdef function (as described below)
change, it is easiest to delete the dump file by hand so that compinit
will re-create it the next time it is run.  The check performed to see
if there are new functions can be omitted by giving the option -C.  In
this case the dump file will only be created if there isn't one already.
Use option -w to explain why a dump file isn't loaded and/or why it's
regenerated.

The dumping is actually done by another function, compdump, but you will
only need to run this yourself if you change the configuration (e.g.
using compdef) and then want to dump the new one.  The name of the old
dumped file will be remembered for this purpose.

If the parameter _compdir is set, compinit uses it as a directory where
completion functions can be found; this is only necessary if they are
not already in the function search path.

For security reasons compinit also checks if the completion system would
use files not owned by root or by the current user, or files in
directories that are world- or group-writable or that are not owned by
root or by the current user.  If such files or directories are found,
compinit will ask if the completion system should really be used.  To
avoid these tests and make all files found be used without asking, use
the option -u, and to make compinit silently ignore all insecure files
and directories use the option -i.  This security check is skipped
entirely when the -C option is given, provided the dumpfile exists.

The security check can be retried at any time by running the function
compaudit.  This is the same check used by compinit, but when it is
executed directly any changes to fpath are made local to the function so
they do not persist.  The directories to be checked may be passed as
arguments; if none are given, compaudit uses fpath and _compdir to find
completion system directories, adding missing ones to fpath as
necessary.  To force a check of exactly the directories currently named
in fpath, set _compdir to an empty string before calling compaudit or
compinit.

The function bashcompinit provides compatibility with bash's
programmable completion system.  When run it will define the functions,
compgen and complete which correspond to the bash builtins with the same
names.  It will then be possible to use completion specifications and
functions written for bash.

20.2.2 Autoloaded files
-----------------------

The convention for autoloaded functions used in completion is that they
start with an underscore; as already mentioned, the fpath/FPATH
parameter must contain the directory in which they are stored.  If zsh
was properly installed on your system, then fpath/FPATH automatically
contains the required directories for the standard functions.

For incomplete installations, if compinit does not find enough files
beginning with an underscore (fewer than twenty) in the search path, it
will try to find more by adding the directory _compdir to the search
path.  If that directory has a subdirectory named Base, all
subdirectories will be added to the path.  Furthermore, if the
subdirectory Base has a subdirectory named Core, compinit will add all
subdirectories of the subdirectories to the path: this allows the
functions to be in the same format as in the zsh source distribution.

When compinit is run, it searches all such files accessible via
fpath/FPATH and reads the first line of each of them.  This line should
contain one of the tags described below.  Files whose first line does
not start with one of these tags are not considered to be part of the
completion system and will not be treated specially.

The tags are:

#compdef NAME ... [ -{p|P} PATTERN ... [ -N NAME ... ] ]
     The file will be made autoloadable and the function defined in it
     will be called when completing NAMEs, each of which is either the
     name of a command whose arguments are to be completed or one of a
     number of special contexts in the form -CONTEXT- described below.

     Each NAME may also be of the form 'CMD=SERVICE'.  When completing
     the command CMD, the function typically behaves as if the command
     (or special context) SERVICE was being completed instead.  This
     provides a way of altering the behaviour of functions that can
     perform many different completions.  It is implemented by setting
     the parameter $service when calling the function; the function may
     choose to interpret this how it wishes, and simpler functions will
     probably ignore it.

     If the #compdef line contains one of the options -p or -P, the
     words following are taken to be patterns.  The function will be
     called when completion is attempted for a command or context that
     matches one of the patterns.  The options -p and -P are used to
     specify patterns to be tried before or after other completions
     respectively.  Hence -P may be used to specify default actions.

     The option -N is used after a list following -p or -P; it specifies
     that remaining words no longer define patterns.  It is possible to
     toggle between the three options as many times as necessary.

#compdef -k STYLE KEY-SEQUENCE ...
     This option creates a widget behaving like the builtin widget STYLE
     and binds it to the given KEY-SEQUENCEs, if any.  The STYLE must be
     one of the builtin widgets that perform completion, namely
     complete-word, delete-char-or-list, expand-or-complete,
     expand-or-complete-prefix, list-choices, menu-complete,
     menu-expand-or-complete, or reverse-menu-complete.  If the
     zsh/complist module is loaded (see *note The zsh/complist Module::)
     the widget menu-select is also available.

     When one of the KEY-SEQUENCEs is typed, the function in the file
     will be invoked to generate the matches.  Note that a key will not
     be re-bound if it already was (that is, was bound to something
     other than undefined-key).  The widget created has the same name as
     the file and can be bound to any other keys using bindkey as usual.

#compdef -K WIDGET-NAME STYLE KEY-SEQUENCE [ NAME STYLE SEQ ... ]
     This is similar to -k except that only one KEY-SEQUENCE argument
     may be given for each WIDGET-NAME STYLE pair.  However, the entire
     set of three arguments may be repeated with a different set of
     arguments.  Note in particular that the WIDGET-NAME must be
     distinct in each set.  If it does not begin with '_' this will be
     added.  The WIDGET-NAME should not clash with the name of any
     existing widget: names based on the name of the function are most
     useful.  For example,

          #compdef -K _foo_complete complete-word "^X^C" \
            _foo_list list-choices "^X^D"

     (all on one line) defines a widget _foo_complete for completion,
     bound to '^X^C', and a widget _foo_list for listing, bound to
     '^X^D'.

#autoload [ OPTIONS ]
     Functions with the #autoload tag are marked for autoloading but are
     not otherwise treated specially.  Typically they are to be called
     from within one of the completion functions.  Any OPTIONS supplied
     will be passed to the autoload builtin; a typical use is +X to
     force the function to be loaded immediately.  Note that the -U and
     -z flags are always added implicitly.

The # is part of the tag name and no white space is allowed after it.
The #compdef tags use the compdef function described below; the main
difference is that the name of the function is supplied implicitly.

The special contexts for which completion functions can be defined are:

-array-value-
     The right hand side of an array-assignment ('NAME=(...)')

-assign-parameter-
     The name of a parameter in an assignment, i.e.  on the left hand
     side of an '='

-brace-parameter-
     The name of a parameter expansion within braces ('${...}')

-command-
     A word in command position

-condition-
     A word inside a condition ('[[...]]')

-default-
     Any word for which no other completion is defined

-equal-
     A word beginning with an equals sign

-first-
     This is tried before any other completion function.  The function
     called may set the _compskip parameter to one of various values:
     all: no further completion is attempted; a string containing the
     substring patterns: no pattern completion functions will be called;
     a string containing default: the function for the '-default-'
     context will not be called, but functions defined for commands will
     be.

-math-
     Inside mathematical contexts, such as '((...))'

-parameter-
     The name of a parameter expansion ('$...')

-redirect-
     The word after a redirection operator.

-subscript-
     The contents of a parameter subscript.

-tilde-
     After an initial tilde ('~'), but before the first slash in the
     word.

-value-
     On the right hand side of an assignment.

Default implementations are supplied for each of these contexts.  In
most cases the context -CONTEXT- is implemented by a corresponding
function _CONTEXT, for example the context '-tilde-' and the function
'_tilde').

The contexts -redirect- and -value- allow extra context-specific
information.  (Internally, this is handled by the functions for each
context calling the function _dispatch.)  The extra information is added
separated by commas.

For the -redirect- context, the extra information is in the form
'-redirect-,OP,COMMAND', where OP is the redirection operator and
COMMAND is the name of the command on the line.  If there is no command
on the line yet, the COMMAND field will be empty.

For the -value- context, the form is '-value-,NAME,COMMAND', where NAME
is the name of the parameter on the left hand side of the assignment.
In the case of elements of an associative array, for example 'assoc=(key
<TAB>', NAME is expanded to 'NAME-KEY'.  In certain special contexts,
such as completing after 'make CFLAGS=', the COMMAND part gives the name
of the command, here make; otherwise it is empty.

It is not necessary to define fully specific completions as the
functions provided will try to generate completions by progressively
replacing the elements with '-default-'.  For example, when completing
after 'foo=<TAB>', _value will try the names '-value-,foo,' (note the
empty COMMAND part), '-value-,foo,-default-'
and'-value-,-default-,-default-', in that order, until it finds a
function to handle the context.

As an example:

     compdef '_files -g "*.log"' '-redirect-,2>,-default-'

completes files matching '*.log' after '2> <TAB>' for any command with
no more specific handler defined.

Also:

     compdef _foo -value-,-default-,-default-

specifies that _foo provides completions for the values of parameters
for which no special function has been defined.  This is usually handled
by the function _value itself.

The same lookup rules are used when looking up styles (as described
below); for example

     zstyle ':completion:*:*:-redirect-,2>,*:*' file-patterns '*.log'

is another way to make completion after '2> <TAB>' complete files
matching '*.log'.

20.2.3 Functions
----------------

The following function is defined by compinit and may be called
directly.

compdef [ -ane ] FUNCTION NAME ... [ -{p|P} PATTERN ... [ -N NAME ...]]
compdef -d NAME ...
compdef -k [ -an ] FUNCTION STYLE KEY-SEQUENCE [ KEY-SEQUENCE ... ]
compdef -K [ -an ] FUNCTION NAME STYLE KEY-SEQ [ NAME STYLE SEQ ... ]
     The first form defines the FUNCTION to call for completion in the
     given contexts as described for the #compdef tag above.

     Alternatively, all the arguments may have the form 'CMD=SERVICE'.
     Here SERVICE should already have been defined by 'CMD1=SERVICE'
     lines in #compdef files, as described above.  The argument for CMD
     will be completed in the same way as SERVICE.

     The FUNCTION argument may alternatively be a string containing
     almost any shell code.  If the string contains an equal sign, the
     above will take precedence.  The option -e may be used to specify
     the first argument is to be evaluated as shell code even if it
     contains an equal sign.  The string will be executed using the eval
     builtin command to generate completions.  This provides a way of
     avoiding having to define a new completion function.  For example,
     to complete files ending in '.h' as arguments to the command foo:

          compdef '_files -g "*.h"' foo

     The option -n prevents any completions already defined for the
     command or context from being overwritten.

     The option -d deletes any completion defined for the command or
     contexts listed.

     The NAMEs may also contain -p, -P and -N options as described for
     the #compdef tag.  The effect on the argument list is identical,
     switching between definitions of patterns tried initially, patterns
     tried finally, and normal commands and contexts.

     The parameter $_compskip may be set by any function defined for a
     pattern context.  If it is set to a value containing the substring
     'patterns' none of the pattern-functions will be called; if it is
     set to a value containing the substring 'all', no other function
     will be called.  Setting $_compskip in this manner is of particular
     utility when using the -p option, as otherwise the dispatcher will
     move on to additional functions (likely the default one) after
     calling the pattern-context one, which can mangle the display of
     completion possibilities if not handled properly.

     The form with -k defines a widget with the same name as the
     FUNCTION that will be called for each of the KEY-SEQUENCEs; this is
     like the #compdef -k tag.  The function should generate the
     completions needed and will otherwise behave like the builtin
     widget whose name is given as the STYLE argument.  The widgets
     usable for this are: complete-word, delete-char-or-list,
     expand-or-complete, expand-or-complete-prefix, list-choices,
     menu-complete, menu-expand-or-complete, and reverse-menu-complete,
     as well as menu-select if the zsh/complist module is loaded.  The
     option -n prevents the key being bound if it is already to bound to
     something other than undefined-key.

     The form with -K is similar and defines multiple widgets based on
     the same FUNCTION, each of which requires the set of three
     arguments NAME, STYLE and KEY-SEQuence, where the latter two are as
     for -k and the first must be a unique widget name beginning with an
     underscore.

     Wherever applicable, the -a option makes the FUNCTION autoloadable,
     equivalent to autoload -U FUNCTION.

The function compdef can be used to associate existing completion
functions with new commands.  For example,

     compdef _pids foo

uses the function _pids to complete process IDs for the command foo.

Note also the _gnu_generic function described below, which can be used
to complete options for commands that understand the '--help' option.


File: zsh.info,  Node: Completion System Configuration,  Next: Control Functions,  Prev: Initialization,  Up: Completion System

20.3 Completion System Configuration
====================================

This section gives a short overview of how the completion system works,
and then more detail on how users can configure how and when matches are
generated.

20.3.1 Overview
---------------

When completion is attempted somewhere on the command line the
completion system begins building the context.  The context represents
everything that the shell knows about the meaning of the command line
and the significance of the cursor position.  This takes account of a
number of things including the command word (such as 'grep' or 'zsh')
and options to which the current word may be an argument (such as the
'-o' option to zsh which takes a shell option as an argument).

The context starts out very generic ("we are beginning a completion")
and becomes more specific as more is learned ("the current word is in a
position that is usually a command name" or "the current word might be a
variable name" and so on).  Therefore the context will vary during the
same call to the completion system.

This context information is condensed into a string consisting of
multiple fields separated by colons, referred to simply as 'the context'
in the remainder of the documentation.  Note that a user of the
completion system rarely needs to compose a context string, unless for
example a new function is being written to perform completion for a new
command.  What a user may need to do is compose a _style_ pattern, which
is matched against a context when needed to look up context-sensitive
options that configure the completion system.

The next few paragraphs explain how a context is composed within the
completion function suite.  Following that is discussion of how _styles_
are defined.  Styles determine such things as how the matches are
generated, similarly to shell options but with much more control.  They
are defined with the zstyle builtin command (*note The zsh/zutil
Module::).

The context string always consists of a fixed set of fields, separated
by colons and with a leading colon before the first.  Fields which are
not yet known are left empty, but the surrounding colons appear anyway.
The fields are always in the order
:completion:FUNCTION:COMPLETER:COMMAND:ARGUMENT:TAG.  These have the
following meaning:

   • The literal string completion, saying that this style is used by
     the completion system.  This distinguishes the context from those
     used by, for example, zle widgets and ZFTP functions.

   • The FUNCTION, if completion is called from a named widget rather
     than through the normal completion system.  Typically this is
     blank, but it is set by special widgets such as predict-on and the
     various functions in the Widget directory of the distribution to
     the name of that function, often in an abbreviated form.

   • The COMPLETER currently active, the name of the function without
     the leading underscore and with other underscores converted to
     hyphens.  A 'completer' is in overall control of how completion is
     to be performed; 'complete' is the simplest, but other completers
     exist to perform related tasks such as correction, or to modify the
     behaviour of a later completer.  See *note Control Functions:: for
     more information.

   • The COMMAND or a special -CONTEXT-, just at it appears following
     the #compdef tag or the compdef function.  Completion functions for
     commands that have sub-commands usually modify this field to
     contain the name of the command followed by a minus sign and the
     sub-command.  For example, the completion function for the cvs
     command sets this field to cvs-add when completing arguments to the
     add subcommand.

   • The ARGUMENT; this indicates which command line or option argument
     we are completing.  For command arguments this generally takes the
     form argument-N, where N is the number of the argument, and for
     arguments to options the form option-OPT-N where N is the number of
     the argument to option OPT.  However, this is only the case if the
     command line is parsed with standard UNIX-style options and
     arguments, so many completions do not set this.

   • The TAG.  As described previously, tags are used to discriminate
     between the types of matches a completion function can generate in
     a certain context.  Any completion function may use any tag name it
     likes, but a list of the more common ones is given below.

The context is gradually put together as the functions are executed,
starting with the main entry point, which adds :completion: and the
FUNCTION element if necessary.  The completer then adds the COMPLETER
element.  The contextual completion adds the COMMAND and ARGUMENT
options.  Finally, the TAG is added when the types of completion are
known.  For example, the context name

     :completion::complete:dvips:option-o-1:files

says that normal completion was attempted as the first argument to the
option -o of the command dvips:

     dvips -o ...

and the completion function will generate filenames.

Usually completion will be tried for all possible tags in an order given
by the completion function.  However, this can be altered by using the
tag-order style.  Completion is then restricted to the list of given
tags in the given order.

The _complete_help bindable command shows all the contexts and tags
available for completion at a particular point.  This provides an easy
way of finding information for tag-order and other styles.  It is
described in *note Bindable Commands::.

When looking up styles the completion system uses full context names,
including the tag.  Looking up the value of a style therefore consists
of two things: the context, which is matched to the most specific (best
fitting) pattern, and the name of the style itself, which must be
matched exactly.  The following examples demonstrate that patterns may
be loosely defined for styles that apply broadly, or as tightly defined
as desired for styles that apply in narrower circumstances.

For example, many completion functions can generate matches in a simple
and a verbose form and use the verbose style to decide which form should
be used.  To make all such functions use the verbose form, put

     zstyle ':completion:*' verbose yes

in a startup file (probably .zshrc).  This gives the verbose style the
value yes in every context inside the completion system, unless that
context has a more specific definition.  It is best to avoid giving the
pattern as '*' in case the style has some meaning outside the completion
system.

Many such general purpose styles can be configured simply by using the
compinstall function.

A more specific example of the use of the verbose style is by the
completion for the kill builtin.  If the style is set, the builtin lists
full job texts and process command lines; otherwise it shows the bare
job numbers and PIDs.  To turn the style off for this use only:

     zstyle ':completion:*:*:kill:*:*' verbose no

For even more control, the style can use one of the tags 'jobs' or
'processes'.  To turn off verbose display only for jobs:

     zstyle ':completion:*:*:kill:*:jobs' verbose no

The -e option to zstyle even allows completion function code to appear
as the argument to a style; this requires some understanding of the
internals of completion functions (see *note Completion Widgets::)).
For example,

     zstyle -e ':completion:*' hosts 'reply=($myhosts)'

This forces the value of the hosts style to be read from the variable
myhosts each time a host name is needed; this is useful if the value of
myhosts can change dynamically.  For another useful example, see the
example in the description of the file-list style below.  This form can
be slow and should be avoided for commonly examined styles such as menu
and list-rows-first.

Note that the order in which styles are _defined_ does not matter; the
style mechanism uses the most specific possible match for a particular
style to determine the set of values.  Strings are preferred over
patterns (for example, ':completion::complete:::foo' is more specific
than ':completion::complete:::*'), and longer patterns are preferred
over the pattern '*'.  See *note The zsh/zutil Module:: for details.

Context patterns that use something other than a wildcard (*) to match
the middle parts of the context -- the COMPLETER, COMMAND, and ARGUMENT
in :completion:FUNCTION:COMPLETER:COMMAND:ARGUMENT:TAG -- should include
all six colons (:) explicitly.  Without this, a pattern such as
:completion:*:foo:* could match foo against a component other than the
intended one (for example, against COMPLETER when a match against
COMMAND was intended).

Style names like those of tags are arbitrary and depend on the
completion function.  However, the following two sections list some of
the most common tags and styles.

20.3.2 Standard Tags
--------------------

Some of the following are only used when looking up particular styles
and do not refer to a type of match.

accounts
     used to look up the users-hosts style

all-expansions
     used by the _expand completer when adding the single string
     containing all possible expansions

all-files
     for the names of all files (as distinct from a particular subset,
     see the globbed-files tag).

arguments
     for arguments to a command

arrays
     for names of array parameters

association-keys
     for keys of associative arrays; used when completing inside a
     subscript to a parameter of this type

bookmarks
     when completing bookmarks (e.g.  for URLs and the zftp function
     suite)

builtins
     for names of builtin commands

characters
     for single characters in arguments of commands such as stty.  Also
     used when completing character classes after an opening bracket

colormapids
     for X colormap ids

colors
     for color names

commands
     for names of external commands.  Also used by complex commands such
     as cvs when completing names subcommands.

contexts
     for contexts in arguments to the zstyle builtin command

corrections
     used by the _approximate and _correct completers for possible
     corrections

cursors
     for cursor names used by X programs

default
     used in some contexts to provide a way of supplying a default when
     more specific tags are also valid.  Note that this tag is used when
     only the FUNCTION field of the context name is set

descriptions
     used when looking up the value of the format style to generate
     descriptions for types of matches

devices
     for names of device special files

directories
     for names of directories -- local-directories is used instead when
     completing arguments of cd and related builtin commands when the
     cdpath array is set

directory-stack
     for entries in the directory stack

displays
     for X display names

domains
     for network domains

email-PLUGIN
     for email addresses from the '_email-PLUGIN' backend of
     _email_addresses

expansions
     used by the _expand completer for individual words (as opposed to
     the complete set of expansions) resulting from the expansion of a
     word on the command line

extensions
     for X server extensions

file-descriptors
     for numbers of open file descriptors

files
     the generic file-matching tag used by functions completing
     filenames

fonts
     for X font names

fstypes
     for file system types (e.g.  for the mount command)

functions
     names of functions -- normally shell functions, although certain
     commands may understand other kinds of function

globbed-files
     for filenames when the name has been generated by pattern matching

groups
     for names of user groups

history-words
     for words from the history

hosts
     for hostnames

indexes
     for array indexes

interfaces
     for network interfaces

jobs
     for jobs (as listed by the 'jobs' builtin)

keymaps
     for names of zsh keymaps

keysyms
     for names of X keysyms

libraries
     for names of system libraries

limits
     for system limits

local-directories
     for names of directories that are subdirectories of the current
     working directory when completing arguments of cd and related
     builtin commands (compare path-directories) -- when the cdpath
     array is unset, directories is used instead

mailboxes
     for e-mail folders

manuals
     for names of manual pages

maps
     for map names (e.g.  NIS maps)

messages
     used to look up the format style for messages

modifiers
     for names of X modifiers

modules
     for modules (e.g.  zsh modules)

my-accounts
     used to look up the users-hosts style

named-directories
     for named directories (you wouldn't have guessed that, would you?)

names
     for all kinds of names

newsgroups
     for USENET groups

nicknames
     for nicknames of NIS maps

options
     for command options

original
     used by the _approximate, _correct and _expand completers when
     offering the original string as a match

other-accounts
     used to look up the users-hosts style

packages
     for packages (e.g.  rpm or installed Debian packages)

parameters
     for names of parameters

path-directories
     for names of directories found by searching the cdpath array when
     completing arguments of cd and related builtin commands (compare
     local-directories)

paths
     used to look up the values of the expand, ambiguous and
     special-dirs styles

pods
     for perl pods (documentation files)

ports
     for communication ports

prefixes
     for prefixes (like those of a URL)

printers
     for print queue names

processes
     for process identifiers

processes-names
     used to look up the command style when generating the names of
     processes for killall

sequences
     for sequences (e.g.  mh sequences)

sessions
     for sessions in the zftp function suite

signals
     for signal names

strings
     for strings (e.g.  the replacement strings for the cd builtin
     command)

styles
     for styles used by the zstyle builtin command

suffixes
     for filename extensions

tags
     for tags (e.g.  rpm tags)

targets
     for makefile targets

time-zones
     for time zones (e.g.  when setting the TZ parameter)

types
     for types of whatever (e.g.  address types for the xhost command)

urls
     used to look up the urls and local styles when completing URLs

users
     for usernames

values
     for one of a set of values in certain lists

variant
     used by _pick_variant to look up the command to run when
     determining what program is installed for a particular command
     name.

visuals
     for X visuals

warnings
     used to look up the format style for warnings

widgets
     for zsh widget names

windows
     for IDs of X windows

zsh-options
     for shell options

20.3.3 Standard Styles
----------------------

Note that the values of several of these styles represent boolean
values.  Any of the strings 'true', 'on', 'yes', and '1' can be used for
the value 'true' and any of the strings 'false', 'off', 'no', and '0'
for the value 'false'.  The behavior for any other value is undefined
except where explicitly mentioned.  The default value may be either
'true' or 'false' if the style is not set.

Some of these styles are tested first for every possible tag
corresponding to a type of match, and if no style was found, for the
default tag.  The most notable styles of this type are menu, list-colors
and styles controlling completion listing such as list-packed and
last-prompt.  When tested for the default tag, only the FUNCTION field
of the context will be set so that a style using the default tag will
normally be defined along the lines of:

     zstyle ':completion:*:default' menu ...

accept-exact
     This is tested for the default tag in addition to the tags valid
     for the current context.  If it is set to 'true' and any of the
     trial matches is the same as the string on the command line, this
     match will immediately be accepted (even if it would otherwise be
     considered ambiguous).

     When completing pathnames (where the tag used is 'paths') this
     style accepts any number of patterns as the value in addition to
     the boolean values.  Pathnames matching one of these patterns will
     be accepted immediately even if the command line contains some more
     partially typed pathname components and these match no file under
     the directory accepted.

     This style is also used by the _expand completer to decide if words
     beginning with a tilde or parameter expansion should be expanded.
     For example, if there are parameters foo and foobar, the string
     '$foo' will only be expanded if accept-exact is set to 'true';
     otherwise the completion system will be allowed to complete $foo to
     $foobar.  If the style is set to 'continue', _expand will add the
     expansion as a match and the completion system will also be allowed
     to continue.

accept-exact-dirs
     This is used by filename completion.  Unlike accept-exact it is a
     boolean.  By default, filename completion examines all components
     of a path to see if there are completions of that component, even
     if the component matches an existing directory.  For example, when
     completion after /usr/bin/, the function examines possible
     completions to /usr.

     When this style is 'true', any prefix of a path that matches an
     existing directory is accepted without any attempt to complete it
     further.  Hence, in the given example, the path /usr/bin/ is
     accepted immediately and completion tried in that directory.

     This style is also useful when completing after directories that
     magically appear when referenced, such as ZFS .zfs directories or
     NetApp .snapshot directories.  When the style is set the shell does
     not check for the existence of the directory within the parent
     directory.

     If you wish to inhibit this behaviour entirely, set the
     path-completion style (see below) to 'false'.

add-space
     This style is used by the _expand completer.  If it is 'true' (the
     default), a space will be inserted after all words resulting from
     the expansion, or a slash in the case of directory names.  If the
     value is 'file', the completer will only add a space to names of
     existing files.  Either a boolean 'true' or the value 'file' may be
     combined with 'subst', in which case the completer will not add a
     space to words generated from the expansion of a substitution of
     the form '$(...)' or '${...}'.

     The _prefix completer uses this style as a simple boolean value to
     decide if a space should be inserted before the suffix.

ambiguous
     This applies when completing non-final components of filename
     paths, in other words those with a trailing slash.  If it is set,
     the cursor is left after the first ambiguous component, even if
     menu completion is in use.  The style is always tested with the
     paths tag.

assign-list
     When completing after an equals sign that is being treated as an
     assignment, the completion system normally completes only one
     filename.  In some cases the value may be a list of filenames
     separated by colons, as with PATH and similar parameters.  This
     style can be set to a list of patterns matching the names of such
     parameters.

     The default is to complete lists when the word on the line already
     contains a colon.

auto-description
     If set, this style's value will be used as the description for
     options that are not described by the completion functions, but
     that have exactly one argument.  The sequence '%d' in the value
     will be replaced by the description for this argument.  Depending
     on personal preferences, it may be useful to set this style to
     something like 'specify: %d'.  Note that this may not work for some
     commands.

avoid-completer
     This is used by the _all_matches completer to decide if the string
     consisting of all matches should be added to the list currently
     being generated.  Its value is a list of names of completers.  If
     any of these is the name of the completer that generated the
     matches in this completion, the string will not be added.

     The default value for this style is '_expand _oldlist _correct
     _approximate', i.e.  it contains the completers for which a string
     with all matches will almost never be wanted.

cache-path
     This style defines the path where any cache files containing dumped
     completion data are stored.  It defaults to '$ZDOTDIR/.zcompcache',
     or '$HOME/.zcompcache' if $ZDOTDIR is not defined.  The completion
     cache will not be used unless the use-cache style is set.

cache-policy
     This style defines the function that will be used to determine
     whether a cache needs rebuilding.  See the section on the
     _cache_invalid function below.

call-command
     This style is used in the function for commands such as make and
     ant where calling the command directly to generate matches suffers
     problems such as being slow or, as in the case of make can
     potentially cause actions in the makefile to be executed.  If it is
     set to 'true' the command is called to generate matches.  The
     default value of this style is 'false'.

command
     In many places, completion functions need to call external commands
     to generate the list of completions.  This style can be used to
     override the command that is called in some such cases.  The
     elements of the value are joined with spaces to form a command line
     to execute.  The value can also start with a hyphen, in which case
     the usual command will be added to the end; this is most useful for
     putting 'builtin' or 'command' in front to make sure the
     appropriate version of a command is called, for example to avoid
     calling a shell function with the same name as an external command.

     As an example, the completion function for process IDs uses this
     style with the processes tag to generate the IDs to complete and
     the list of processes to display (if the verbose style is 'true').
     The list produced by the command should look like the output of the
     ps command.  The first line is not displayed, but is searched for
     the string 'PID' (or 'pid') to find the position of the process IDs
     in the following lines.  If the line does not contain 'PID', the
     first numbers in each of the other lines are taken as the process
     IDs to complete.

     Note that the completion function generally has to call the
     specified command for each attempt to generate the completion list.
     Hence care should be taken to specify only commands that take a
     short time to run, and in particular to avoid any that may never
     terminate.

command-path
     This is a list of directories to search for commands to complete.
     The default for this style is the value of the special parameter
     path.

commands
     This is used by the function completing sub-commands for the system
     initialisation scripts (residing in /etc/init.d or somewhere not
     too far away from that).  Its values give the default commands to
     complete for those commands for which the completion function isn't
     able to find them out automatically.  The default for this style
     are the two strings 'start' and 'stop'.

complete
     This is used by the _expand_alias function when invoked as a
     bindable command.  If set to 'true' and the word on the command
     line is not the name of an alias, matching alias names will be
     completed.

complete-options
     This is used by the completer for cd, chdir and pushd.  For these
     commands a - is used to introduce a directory stack entry and
     completion of these is far more common than completing options.
     Hence unless the value of this style is 'true' options will not be
     completed, even after an initial -.  If it is 'true', options will
     be completed after an initial - unless there is a preceding -- on
     the command line.

completer
     The strings given as the value of this style provide the names of
     the completer functions to use.  The available completer functions
     are described in *note Control Functions::.

     Each string may be either the name of a completer function or a
     string of the form 'FUNCTION:NAME'.  In the first case the
     COMPLETER field of the context will contain the name of the
     completer without the leading underscore and with all other
     underscores replaced by hyphens.  In the second case the FUNCTION
     is the name of the completer to call, but the context will contain
     the user-defined NAME in the COMPLETER field of the context.  If
     the NAME starts with a hyphen, the string for the context will be
     build from the name of the completer function as in the first case
     with the NAME appended to it.  For example:

          zstyle ':completion:*' completer _complete _complete:-foo

     Here, completion will call the _complete completer twice, once
     using 'complete' and once using 'complete-foo' in the COMPLETER
     field of the context.  Normally, using the same completer more than
     once only makes sense when used with the 'FUNCTIONS:NAME' form,
     because otherwise the context name will be the same in all calls to
     the completer; possible exceptions to this rule are the _ignored
     and _prefix completers.

     The default value for this style is '_complete _ignored': only
     completion will be done, first using the ignored-patterns style and
     the $fignore array and then without ignoring matches.

condition
     This style is used by the _list completer function to decide if
     insertion of matches should be delayed unconditionally.  The
     default is 'true'.

delimiters
     This style is used when adding a delimiter for use with history
     modifiers or glob qualifiers that have delimited arguments.  It is
     an array of preferred delimiters to add.  Non-special characters
     are preferred as the completion system may otherwise become
     confused.  The default list is :, +, /, -, %.  The list may be
     empty to force a delimiter to be typed.

disabled
     If this is set to 'true', the _expand_alias completer and bindable
     command will try to expand disabled aliases, too.  The default is
     'false'.

domains
     A list of names of network domains for completion.  If this is not
     set, domain names will be taken from the file /etc/resolv.conf.

environ
     The environ style is used when completing for 'sudo'.  It is set to
     an array of 'VAR=VALUE' assignments to be exported into the local
     environment before the completion for the target command is
     invoked.
          zstyle ':completion:*:sudo::' environ \
            PATH="/sbin:/usr/sbin:$PATH" HOME="/root"

expand
     This style is used when completing strings consisting of multiple
     parts, such as path names.

     If one of its values is the string 'prefix', the partially typed
     word from the line will be expanded as far as possible even if
     trailing parts cannot be completed.

     If one of its values is the string 'suffix', matching names for
     components after the first ambiguous one will also be added.  This
     means that the resulting string is the longest unambiguous string
     possible.  However, menu completion can be used to cycle through
     all matches.

extra-verbose
     If this style set to 'true', the completion listing is still more
     verbose.

     Currently, it is used for commands and parameters tags.  If it is
     'true' for the commands (or parameters) tag, short descriptions of
     the commands (or the values of the parameters) are displayed along
     with the command (or parameter) names.

fake
     This style may be set for any completion context.  It specifies
     additional strings that will always be completed in that context.
     The form of each string is 'VALUE:DESCRIPTION'; the colon and
     description may be omitted, but any literal colons in VALUE must be
     quoted with a backslash.  Any DESCRIPTION provided is shown
     alongside the value in completion listings.

     It is important to use a sufficiently restrictive context when
     specifying fake strings.  Note that the styles fake-files and
     fake-parameters provide additional features when completing files
     or parameters.

fake-always
     This works identically to the fake style except that the
     ignored-patterns style is not applied to it.  This makes it
     possible to override a set of matches completely by setting the
     ignored patterns to '*'.

     The following shows a way of supplementing any tag with arbitrary
     data, but having it behave for display purposes like a separate
     tag.  In this example we use the features of the tag-order style to
     divide the named-directories tag into two when performing
     completion with the standard completer complete for arguments of
     cd.  The tag named-directories-normal behaves as normal, but the
     tag named-directories-mine contains a fixed set of directories.
     This has the effect of adding the match group 'extra directories'
     with the given completions.

          zstyle ':completion::complete:cd:*' tag-order \
            'named-directories:-mine:extra\ directories
            named-directories:-normal:named\ directories *'
          zstyle ':completion::complete:cd:*:named-directories-mine' \
            fake-always mydir1 mydir2
          zstyle ':completion::complete:cd:*:named-directories-mine' \
            ignored-patterns '*'

fake-files
     This style is used when completing files and looked up without a
     tag.  Its values are of the form 'DIR:NAMES...'.  This will add the
     NAMES (strings separated by spaces) as possible matches when
     completing in the directory DIR, even if no such files really
     exist.  The dir may be a pattern; pattern characters or colons in
     DIR should be quoted with a backslash to be treated literally.

     This can be useful on systems that support special file systems
     whose top-level pathnames can not be listed or generated with glob
     patterns (but see accept-exact-dirs for a more general way of
     dealing with this problem).  It can also be used for directories
     for which one does not have read permission.

     The pattern form can be used to add a certain 'magic' entry to all
     directories on a particular file system.

fake-parameters
     This is used by the completion function for parameter names.  Its
     values are names of parameters that might not yet be set but should
     be completed nonetheless.  Each name may also be followed by a
     colon and a string specifying the type of the parameter (like
     'scalar', 'array' or 'integer').  If the type is given, the name
     will only be completed if parameters of that type are required in
     the particular context.  Names for which no type is specified will
     always be completed.

file-list
     This style controls whether files completed using the standard
     builtin mechanism are to be listed with a long list similar to ls
     -l.  Note that this feature uses the shell module zsh/stat for file
     information; this loads the builtin stat which will replace any
     external stat executable.  To avoid this the following code can be
     included in an initialization file:

          zmodload -i zsh/stat
          disable stat

     The style may either be set to a 'true' value (or 'all'), or one of
     the values 'insert' or 'list', indicating that files are to be
     listed in long format in all circumstances, or when attempting to
     insert a file name, or when listing file names without attempting
     to insert one.

     More generally, the value may be an array of any of the above
     values, optionally followed by =NUM.  If NUM is present it gives
     the maximum number of matches for which long listing style will be
     used.  For example,

          zstyle ':completion:*' file-list list=20 insert=10

     specifies that long format will be used when listing up to 20 files
     or inserting a file with up to 10 matches (assuming a listing is to
     be shown at all, for example on an ambiguous completion), else
     short format will be used.

          zstyle -e ':completion:*' file-list \
                 '(( ${+NUMERIC} )) && reply=(true)'

     specifies that long format will be used any time a numeric argument
     is supplied, else short format.

file-patterns
     This is used by the standard function for completing filenames,
     _files.  If the style is unset up to three tags are offered,
     'globbed-files','directories' and 'all-files', depending on the
     types of files expected by the caller of _files.  The first two
     ('globbed-files' and 'directories') are normally offered together
     to make it easier to complete files in sub-directories.

     The file-patterns style provides alternatives to the default tags,
     which are not used.  Its value consists of elements of the form
     'PATTERN:TAG'; each string may contain any number of such
     specifications separated by spaces.

     The PATTERN is a pattern that is to be used to generate filenames.
     Any occurrence of the sequence '%p' is replaced by any pattern(s)
     passed by the function calling _files.  Colons in the pattern must
     be preceded by a backslash to make them distinguishable from the
     colon before the TAG.  If more than one pattern is needed, the
     patterns can be given inside braces, separated by commas.

     The TAGs of all strings in the value will be offered by _files and
     used when looking up other styles.  Any TAGs in the same word will
     be offered at the same time and before later words.  If no ':TAG'
     is given the 'files' tag will be used.

     The TAG may also be followed by an optional second colon and a
     description, which will be used for the '%d' in the value of the
     format style (if that is set) instead of the default description
     supplied by the completion function.  The inclusion of a
     description also gives precedence to associated options such as for
     completion grouping so it can be used where files should be
     separated.

     For example, to make the rm command first complete only names of
     object files and then the names of all files if there is no
     matching object file:

          zstyle ':completion:*:*:rm:*:*' file-patterns \
              '*.o:object-files' '%p:all-files'

     To alter the default behaviour of file completion -- offer files
     matching a pattern and directories on the first attempt, then all
     files -- to offer only matching files on the first attempt, then
     directories, and finally all files:

          zstyle ':completion:*' file-patterns \
              '%p:globbed-files' '*(-/):directories' '*:all-files'

     This works even where there is no special pattern: _files matches
     all files using the pattern '*' at the first step and stops when it
     sees this pattern.  Note also it will never try a pattern more than
     once for a single completion attempt.

     To separate directories into a separate group from the files but
     still complete them at the first attempt, a description needs to be
     given.  Note that directories need to be explicitly excluded from
     the globbed-files because '*' will match directories.  For
     grouping, it is also necessary to set the group-name style.

          zstyle ':completion:*' file-patterns \
              '%p(^-/):globbed-files *(-/):directories:location'

     During the execution of completion functions, the EXTENDED_GLOB
     option is in effect, so the characters '#', '~' and '^' have
     special meanings in the patterns.

file-sort
     The standard filename completion function uses this style without a
     tag to determine in which order the names should be listed; menu
     completion will cycle through them in the same order.  The possible
     values are: 'size' to sort by the size of the file; 'links' to sort
     by the number of links to the file; 'modification' (or 'time' or
     'date') to sort by the last modification time; 'access' to sort by
     the last access time; and 'inode' (or 'change') to sort by the last
     inode change time.  If the style is set to any other value, or is
     unset, files will be sorted alphabetically by name.  If the value
     contains the string 'reverse', sorting is done in the opposite
     order.  If the value contains the string 'follow', timestamps are
     associated with the targets of symbolic links; the default is to
     use the timestamps of the links themselves.

file-split-chars
     A set of characters that will cause _all_ file completions for the
     given context to be split at the point where any of the characters
     occurs.  A typical use is to set the style to :; then everything up
     to and including the last : in the string so far is ignored when
     completing files.  As this is quite heavy-handed, it is usually
     preferable to update completion functions for contexts where this
     behaviour is useful.

filter
     The ldap plugin of email address completion (see _email_addresses)
     uses this style to specify the attributes to match against when
     filtering entries.  So for example, if the style is set to 'sn',
     matching is done against surnames.  Standard LDAP filtering is used
     so normal completion matching is bypassed.  If this style is not
     set, the LDAP plugin is skipped.  You may also need to set the
     command style to specify how to connect to your LDAP server.

force-list
     This forces a list of completions to be shown at any point where
     listing is done, even in cases where the list would usually be
     suppressed.  For example, normally the list is only shown if there
     are at least two different matches.  By setting this style to
     'always', the list will always be shown, even if there is only a
     single match that will immediately be accepted.  The style may also
     be set to a number.  In this case the list will be shown if there
     are at least that many matches, even if they would all insert the
     same string.

     This style is tested for the default tag as well as for each tag
     valid for the current completion.  Hence the listing can be forced
     only for certain types of match.

format
     If this is set for the descriptions tag, its value is used as a
     string to display above matches in completion lists.  The sequence
     '%d' in this string will be replaced with a short description of
     what these matches are.  This string may also contain the output
     attribute sequences understood by compadd -X (see *note Completion
     Widgets::).

     The style is tested with each tag valid for the current completion
     before it is tested for the descriptions tag.  Hence different
     format strings can be defined for different types of match.

     Note also that some completer functions define additional
     '%'-sequences.  These are described for the completer functions
     that make use of them.

     Some completion functions display messages that may be customised
     by setting this style for the messages tag.  Here, the '%d' is
     replaced with a message given by the completion function.

     Finally, the format string is looked up with the warnings tag, for
     use when no matches could be generated at all.  In this case the
     '%d' is replaced with the descriptions for the matches that were
     expected separated by spaces.  The sequence '%D' is replaced with
     the same descriptions separated by newlines.

     It is possible to use printf-style field width specifiers with '%d'
     and similar escape sequences.  This is handled by the zformat
     builtin command from the zsh/zutil module, see *note The zsh/zutil
     Module::.

gain-privileges
     If set to true, this style enables the use of commands like sudo or
     doas to gain extra privileges when retrieving information for
     completion.  This is only done when a command such as sudo appears
     on the command-line.  To force the use of, e.g.  sudo or to
     override any prefix that might be added due to gain-privileges, the
     command style can be used with a value that begins with a hyphen.

glob
     This is used by the _expand completer.  If it is set to 'true' (the
     default), globbing will be attempted on the words resulting from a
     previous substitution (see the substitute style) or else the
     original string from the line.

global
     If this is set to 'true' (the default), the _expand_alias completer
     and bindable command will try to expand global aliases.

group-name
     The completion system can group different types of matches, which
     appear in separate lists.  This style can be used to give the names
     of groups for particular tags.  For example, in command position
     the completion system generates names of builtin and external
     commands, names of aliases, shell functions and parameters and
     reserved words as possible completions.  To have the external
     commands and shell functions listed separately:

          zstyle ':completion:*:*:-command-:*:commands' \
                 group-name commands
          zstyle ':completion:*:*:-command-:*:functions' \
                 group-name functions

     As a consequence, any match with the same tag will be displayed in
     the same group.

     If the name given is the empty string the name of the tag for the
     matches will be used as the name of the group.  So, to have all
     different types of matches displayed separately, one can just set:

          zstyle ':completion:*' group-name ''

     All matches for which no group name is defined will be put in a
     group named -default-.

     To display the group name in the output, see the format style
     (q.v.)  under the descriptions tag.

group-order
     This style is additional to the group-name style to specify the
     order for display of the groups defined by that style (compare
     tag-order, which determines which completions appear at all).  The
     groups named are shown in the given order; any other groups are
     shown in the order defined by the completion function.

     For example, to have names of builtin commands, shell functions and
     external commands appear in that order when completing in command
     position:

          zstyle ':completion:*:*:-command-:*:*' group-order \
                 builtins functions commands

groups
     A list of names of UNIX groups.  If this is not set, group names
     are taken from the YP database or the file '/etc/group'.

hidden
     If this is set to 'true', matches for the given context will not be
     listed, although any description for the matches set with the
     format style will be shown.  If it is set to 'all', not even the
     description will be displayed.

     Note that the matches will still be completed; they are just not
     shown in the list.  To avoid having matches considered as possible
     completions at all, the tag-order style can be modified as
     described below.

hosts
     A list of names of hosts that should be completed.  If this is not
     set, hostnames are taken from the file '/etc/hosts'.

hosts-ports
     This style is used by commands that need or accept hostnames and
     network ports.  The strings in the value should be of the form
     'HOST:PORT'.  Valid ports are determined by the presence of
     hostnames; multiple ports for the same host may appear.

ignore-line
     This is tested for each tag valid for the current completion.  If
     it is set to 'true', none of the words that are already on the line
     will be considered as possible completions.  If it is set to
     'current', the word the cursor is on will not be considered as a
     possible completion.  The value 'current-shown' is similar but only
     applies if the list of completions is currently shown on the
     screen.  Finally, if the style is set to 'other', all words on the
     line except for the current one will be excluded from the possible
     completions.

     The values 'current' and 'current-shown' are a bit like the
     opposite of the accept-exact style: only strings with missing
     characters will be completed.

     Note that you almost certainly don't want to set this to 'true' or
     'other' for a general context such as ':completion:*'.  This is
     because it would disallow completion of, for example, options
     multiple times even if the command in question accepts the option
     more than once.

ignore-parents
     The style is tested without a tag by the function completing
     pathnames in order to determine whether to ignore the names of
     directories already mentioned in the current word, or the name of
     the current working directory.  The value must include one or both
     of the following strings:

     parent
          The name of any directory whose path is already contained in
          the word on the line is ignored.  For example, when completing
          after foo/../, the directory foo will not be considered a
          valid completion.

     pwd
          The name of the current working directory will not be
          completed; hence, for example, completion after ../ will not
          use the name of the current directory.

     In addition, the value may include one or both of:

     ..
          Ignore the specified directories only when the word on the
          line contains the substring '../'.

     directory
          Ignore the specified directories only when names of
          directories are completed, not when completing names of files.

     Excluded values act in a similar fashion to values of the
     ignored-patterns style, so they can be restored to consideration by
     the _ignored completer.

ignored-patterns
     A list of patterns; any trial completion matching one of the
     patterns will be excluded from consideration.  The _ignored
     completer can appear in the list of completers to restore the
     ignored matches.  This is a more configurable version of the shell
     parameter $fignore.

     Note that the EXTENDED_GLOB option is set during the execution of
     completion functions, so the characters '#', '~' and '^' have
     special meanings in the patterns.

insert
     This style is used by the _all_matches completer to decide whether
     to insert the list of all matches unconditionally instead of adding
     the list as another match.

insert-ids
     When completing process IDs, for example as arguments to the kill
     and wait builtins the name of a command may be converted to the
     appropriate process ID. A problem arises when the process name
     typed is not unique.  By default (or if this style is set
     explicitly to 'menu') the name will be converted immediately to a
     set of possible IDs, and menu completion will be started to cycle
     through them.

     If the value of the style is 'single', the shell will wait until
     the user has typed enough to make the command unique before
     converting the name to an ID; attempts at completion will be
     unsuccessful until that point.  If the value is any other string,
     menu completion will be started when the string typed by the user
     is longer than the common prefix to the corresponding IDs.

insert-sections
     This style is used with tags of the form 'manuals.X' when
     completing names of manual pages.  If set and the X in the tag name
     matches the section number of the page being completed, the section
     number is inserted along with the page name.  For example, given

          zstyle ':completion:*:manuals.*' insert-sections true

     man ssh_<TAB> may be completed to man 5 ssh_config.

     The value may also be set to one of 'prepend', or 'suffix'.
     'prepend' behaves the same as 'true' as in the above example, while
     'suffix' would complete man ssh_<TAB> as man ssh_config.5.

     This is especially useful in conjunction with separate-sections, as
     it ensures that the page requested of man corresponds to the one
     displayed in the completion listing when there are multiple pages
     with the same name (e.g., printf(1) and printf(3)).

     The default for this style is 'false'.

insert-tab
     If this is set to 'true', the completion system will insert a TAB
     character (assuming that was used to start completion) instead of
     performing completion when there is no non-blank character to the
     left of the cursor.  If it is set to 'false', completion will be
     done even there.

     The value may also contain the substrings 'pending' or
     'pending=VAL'.  In this case, the typed character will be inserted
     instead of starting completion when there is unprocessed input
     pending.  If a VAL is given, completion will not be done if there
     are at least that many characters of unprocessed input.  This is
     often useful when pasting characters into a terminal.  Note
     however, that it relies on the $PENDING special parameter from the
     zsh/zle module being set properly which is not guaranteed on all
     platforms.

     The default value of this style is 'true' except for completion
     within vared builtin command where it is 'false'.

insert-unambiguous
     This is used by the _match and _approximate completers.  These
     completers are often used with menu completion since the word typed
     may bear little resemblance to the final completion.  However, if
     this style is 'true', the completer will start menu completion only
     if it could find no unambiguous initial string at least as long as
     the original string typed by the user.

     In the case of the _approximate completer, the completer field in
     the context will already have been set to one of correct-NUM or
     approximate-NUM, where NUM is the number of errors that were
     accepted.

     In the case of the _match completer, the style may also be set to
     the string 'pattern'.  Then the pattern on the line is left
     unchanged if it does not match unambiguously.

keep-prefix
     This style is used by the _expand completer.  If it is 'true', the
     completer will try to keep a prefix containing a tilde or parameter
     expansion.  Hence, for example, the string '~/f*' would be expanded
     to '~/foo' instead of '/home/user/foo'.  If the style is set to
     'changed' (the default), the prefix will only be left unchanged if
     there were other changes between the expanded words and the
     original word from the command line.  Any other value forces the
     prefix to be expanded unconditionally.

     The behaviour of _expand when this style is 'true' is to cause
     _expand to give up when a single expansion with the restored prefix
     is the same as the original; hence any remaining completers may be
     called.

known-hosts-files
     This style should contain a list of files to search for host names
     and (if the use-ip style is set) IP addresses in a format
     compatible with ssh known_hosts files.  If it is not set, the files
     /etc/ssh/ssh_known_hosts and ~/.ssh/known_hosts are used.

last-prompt
     This is a more flexible form of the ALWAYS_LAST_PROMPT option.  If
     it is 'true', the completion system will try to return the cursor
     to the previous command line after displaying a completion list.
     It is tested for all tags valid for the current completion, then
     the default tag.  The cursor will be moved back to the previous
     line if this style is 'true' for all types of match.  Note that
     unlike the ALWAYS_LAST_PROMPT option this is independent of the
     numeric argument.

list
     This style is used by the _history_complete_word bindable command.
     If it is set to 'true' it has no effect.  If it is set to 'false'
     matches will not be listed.  This overrides the setting of the
     options controlling listing behaviour, in particular AUTO_LIST.
     The context always starts with ':completion:history-words'.

list-colors
     If the zsh/complist module is loaded, this style can be used to set
     color specifications.  This mechanism replaces the use of the
     ZLS_COLORS and ZLS_COLOURS parameters described in *note The
     zsh/complist Module::, but the syntax is the same.

     If this style is set for the default tag, the strings in the value
     are taken as specifications that are to be used everywhere.  If it
     is set for other tags, the specifications are used only for matches
     of the type described by the tag.  For this to work best, the
     group-name style must be set to an empty string.

     In addition to setting styles for specific tags, it is also
     possible to use group names specified explicitly by the group-name
     tag together with the '(group)' syntax allowed by the ZLS_COLORS
     and ZLS_COLOURS parameters and simply using the default tag.

     It is possible to use any color specifications already set up for
     the GNU version of the ls command:

          zstyle ':completion:*:default' list-colors \
                 ${(s.:.)LS_COLORS}

     The default colors are the same as for the GNU ls command and can
     be obtained by setting the style to an empty string (i.e.  '').

list-dirs-first
     This is used by file completion and corresponds to a particular
     setting of the file-patterns style.  If set, the default
     directories to be completed are listed separately from and before
     completion for other files.

list-grouped
     If this style is 'true' (the default), the completion system will
     try to make certain completion listings more compact by grouping
     matches.  For example, options for commands that have the same
     description (shown when the verbose style is set to 'true') will
     appear as a single entry.  However, menu selection can be used to
     cycle through all the matches.

list-packed
     This is tested for each tag valid in the current context as well as
     the default tag.  If it is set to 'true', the corresponding matches
     appear in listings as if the LIST_PACKED option were set.  If it is
     set to 'false', they are listed normally.

list-prompt
     If this style is set for the default tag, completion lists that
     don't fit on the screen can be scrolled (see *note The zsh/complist
     Module::).  The value, if not the empty string, will be displayed
     after every screenful and the shell will prompt for a key press; if
     the style is set to the empty string, a default prompt will be
     used.

     The value may contain the escape sequences: '%l' or '%L', which
     will be replaced by the number of the last line displayed and the
     total number of lines; '%m' or '%M', the number of the last match
     shown and the total number of matches; and '%p' and '%P', 'Top'
     when at the beginning of the list, 'Bottom' when at the end and the
     position shown as a percentage of the total length otherwise.  In
     each case the form with the uppercase letter will be replaced by a
     string of fixed width, padded to the right with spaces, while the
     lowercase form will be replaced by a variable width string.  As in
     other prompt strings, the escape sequences '%S', '%s', '%B', '%b',
     '%U', '%u' for entering and leaving the display modes standout,
     bold and underline, and '%F', '%f', '%K', '%k' for changing the
     foreground background colour, are also available, as is the form
     '%{...%}' for enclosing escape sequences which display with zero
     (or, with a numeric argument, some other) width.

     After deleting this prompt the variable LISTPROMPT should be unset
     for the removal to take effect.

list-rows-first
     This style is tested in the same way as the list-packed style and
     determines whether matches are to be listed in a rows-first fashion
     as if the LIST_ROWS_FIRST option were set.

list-separator
     The value of this style is used in completion listing to separate
     the string to complete from a description when possible (e.g.  when
     completing options).  It defaults to '--' (two hyphens).

list-suffixes
     This style is used by the function that completes filenames.  If it
     is 'true', and completion is attempted on a string containing
     multiple partially typed pathname components, all ambiguous
     components will be shown.  Otherwise, completion stops at the first
     ambiguous component.

local
     This is for use with functions that complete URLs for which the
     corresponding files are available directly from the file system.
     Its value should consist of three strings: a hostname, the path to
     the default web pages for the server, and the directory name used
     by a user placing web pages within their home area.

     For example:

          zstyle ':completion:*' local toast \
              /var/http/public/toast public_html

     Completion after 'http://toast/stuff/' will look for files in the
     directory /var/http/public/toast/stuff, while completion after
     'http://toast/~yousir/' will look for files in the directory
     ~yousir/public_html.

mail-directory
     If set, zsh will assume that mailbox files can be found in the
     directory specified.  It defaults to '~/Mail'.

match-original
     This is used by the _match completer.  If it is set to only, _match
     will try to generate matches without inserting a '*' at the cursor
     position.  If set to any other non-empty value, it will first try
     to generate matches without inserting the '*' and if that yields no
     matches, it will try again with the '*' inserted.  If it is unset
     or set to the empty string, matching will only be performed with
     the '*' inserted.

matcher
     This style is tested separately for each tag valid in the current
     context.  Its value is placed before any match specifications given
     by the matcher-list style so can override them via the use of an x:
     specification.  The value should be in the form described in *note
     Completion Matching Control::.  For examples of this, see the
     description of the tag-order style.

     For notes comparing the use of this and the matcher-list style, see
     under the description of the tag-order style.

matcher-list
     This style can be set to a list of match specifications that are to
     be applied everywhere.  Match specifications are described in *note
     Completion Matching Control::.  The completion system will try them
     one after another for each completer selected.  For example, to try
     first simple completion and, if that generates no matches,
     case-insensitive completion:

          zstyle ':completion:*' matcher-list '' 'm:{a-zA-Z}={A-Za-z}'

     By default each specification replaces the previous one; however,
     if a specification is prefixed with +, it is added to the existing
     list.  Hence it is possible to create increasingly general
     specifications without repetition:

          zstyle ':completion:*' matcher-list \
                 '' '+m:{a-z}={A-Z}' '+m:{A-Z}={a-z}'

     It is possible to create match specifications valid for particular
     completers by using the third field of the context.  This applies
     only to completers that override the global matcher-list, which as
     of this writing includes only _prefix and _ignored.  For example,
     to use the completers _complete and _prefix but allow
     case-insensitive completion only with _complete:

          zstyle ':completion:*' completer _complete _prefix
          zstyle ':completion:*:complete:*:*:*' matcher-list \
                 '' 'm:{a-zA-Z}={A-Za-z}'

     User-defined names, as explained for the completer style, are
     available.  This makes it possible to try the same completer more
     than once with different match specifications each time.  For
     example, to try normal completion without a match specification,
     then normal completion with case-insensitive matching, then
     correction, and finally partial-word completion:

          zstyle ':completion:*' completer \
              _complete _correct _complete:foo
          zstyle ':completion:*:complete:*:*:*' matcher-list \
              '' 'm:{a-zA-Z}={A-Za-z}'
          zstyle ':completion:*:foo:*:*:*' matcher-list \
              'm:{a-zA-Z}={A-Za-z} r:|[-_./]=* r:|=*'

     If the style is unset in any context no match specification is
     applied.  Note also that some completers such as _correct and
     _approximate do not use the match specifications at all, though
     these completers will only ever be called once even if the
     matcher-list contains more than one element.

     Where multiple specifications are useful, note that the _entire_
     completion is done for each element of matcher-list, which can
     quickly reduce the shell's performance.  As a rough rule of thumb,
     one to three strings will give acceptable performance.  On the
     other hand, putting multiple space-separated values into the same
     string does not have an appreciable impact on performance.

     If there is no current matcher or it is empty, and the option
     NO_CASE_GLOB is in effect, the matching for files is performed
     case-insensitively in any case.  However, any matcher must
     explicitly specify case-insensitive matching if that is required.

     For notes comparing the use of this and the matcher style, see
     under the description of the tag-order style.

max-errors
     This is used by the _approximate and _correct completer functions
     to determine the maximum number of errors to allow.  The completer
     will try to generate completions by first allowing one error, then
     two errors, and so on, until either a match or matches were found
     or the maximum number of errors given by this style has been
     reached.

     If the value for this style contains the string 'numeric', the
     completer function will take any numeric argument as the maximum
     number of errors allowed.  For example, with

          zstyle ':completion:*:approximate:::' max-errors 2 numeric

     two errors are allowed if no numeric argument is given, but with a
     numeric argument of six (as in 'ESC-6 TAB'), up to six errors are
     accepted.  Hence with a value of '0 numeric', no correcting
     completion will be attempted unless a numeric argument is given.

     If the value contains the string 'not-numeric', the completer will
     _not_ try to generate corrected completions when given a numeric
     argument, so in this case the number given should be greater than
     zero.  For example, '2 not-numeric' specifies that correcting
     completion with two errors will usually be performed, but if a
     numeric argument is given, correcting completion will not be
     performed.

     The default value for this style is '2 numeric'.

max-matches-width
     This style is used to determine the trade off between the width of
     the display used for matches and the width used for their
     descriptions when the verbose style is in effect.  The value gives
     the number of display columns to reserve for the matches.  The
     default is half the width of the screen.

     This has the most impact when several matches have the same
     description and so will be grouped together.  Increasing the style
     will allow more matches to be grouped together; decreasing it will
     allow more of the description to be visible.

menu
     If this is 'true' in the context of any of the tags defined for the
     current completion menu completion will be used.  The value for a
     specific tag will take precedence over that for the 'default' tag.

     If none of the values found in this way is 'true' but at least one
     is set to 'auto', the shell behaves as if the AUTO_MENU option is
     set.

     If one of the values is explicitly set to 'false', menu completion
     will be explicitly turned off, overriding the MENU_COMPLETE option
     and other settings.

     In the form 'yes=NUM', where 'yes' may be any of the 'true' values
     ('yes', 'true', 'on' and '1'), menu completion will be turned on if
     there are at least NUM matches.  In the form 'yes=long', menu
     completion will be turned on if the list does not fit on the
     screen.  This does not activate menu completion if the widget
     normally only lists completions, but menu completion can be
     activated in that case with the value 'yes=long-list' (Typically,
     the value 'select=long-list' described later is more useful as it
     provides control over scrolling.)

     Similarly, with any of the 'false' values (as in 'no=10'), menu
     completion will _not_ be used if there are NUM or more matches.

     The value of this widget also controls menu selection, as
     implemented by the zsh/complist module.  The following values may
     appear either alongside or instead of the values above.

     If the value contains the string 'select', menu selection will be
     started unconditionally.

     In the form 'select=NUM', menu selection will only be started if
     there are at least NUM matches.  If the values for more than one
     tag provide a number, the smallest number is taken.

     Menu selection can be turned off explicitly by defining a value
     containing the string'no-select'.

     It is also possible to start menu selection only if the list of
     matches does not fit on the screen by using the value
     'select=long'.  To start menu selection even if the current widget
     only performs listing, use the value 'select=long-list'.

     To turn on menu completion or menu selection when there are a
     certain number of matches _or_ the list of matches does not fit on
     the screen, both of 'yes=' and 'select=' may be given twice, once
     with a number and once with 'long' or 'long-list'.

     Finally, it is possible to activate two special modes of menu
     selection.  The word 'interactive' in the value causes interactive
     mode to be entered immediately when menu selection is started; see
     *note The zsh/complist Module:: for a description of interactive
     mode.  Including the string 'search' does the same for incremental
     search mode.  To select backward incremental search, include the
     string 'search-backward'.

muttrc
     If set, gives the location of the mutt configuration file.  It
     defaults to '~/.muttrc'.

numbers
     This is used with the jobs tag.  If it is 'true', the shell will
     complete job numbers instead of the shortest unambiguous prefix of
     the job command text.  If the value is a number, job numbers will
     only be used if that many words from the job descriptions are
     required to resolve ambiguities.  For example, if the value is '1',
     strings will only be used if all jobs differ in the first word on
     their command lines.

old-list
     This is used by the _oldlist completer.  If it is set to 'always',
     then standard widgets which perform listing will retain the current
     list of matches, however they were generated; this can be turned
     off explicitly with the value 'never', giving the behaviour without
     the _oldlist completer.  If the style is unset, or any other value,
     then the existing list of completions is displayed if it is not
     already; otherwise, the standard completion list is generated; this
     is the default behaviour of _oldlist.  However, if there is an old
     list and this style contains the name of the completer function
     that generated the list, then the old list will be used even if it
     was generated by a widget which does not do listing.

     For example, suppose you type ^Xc to use the _correct_word widget,
     which generates a list of corrections for the word under the
     cursor.  Usually, typing ^D would generate a standard list of
     completions for the word on the command line, and show that.  With
     _oldlist, it will instead show the list of corrections already
     generated.

     As another example consider the _match completer: with the
     insert-unambiguous style set to 'true' it inserts only a common
     prefix string, if there is any.  However, this may remove parts of
     the original pattern, so that further completion could produce more
     matches than on the first attempt.  By using the _oldlist completer
     and setting this style to _match, the list of matches generated on
     the first attempt will be used again.

old-matches
     This is used by the _all_matches completer to decide if an old list
     of matches should be used if one exists.  This is selected by one
     of the 'true' values or by the string 'only'.  If the value is
     'only', _all_matches will only use an old list and won't have any
     effect on the list of matches currently being generated.

     If this style is set it is generally unwise to call the
     _all_matches completer unconditionally.  One possible use is for
     either this style or the completer style to be defined with the -e
     option to zstyle to make the style conditional.

old-menu
     This is used by the _oldlist completer.  It controls how menu
     completion behaves when a completion has already been inserted and
     the user types a standard completion key such as TAB.  The default
     behaviour of _oldlist is that menu completion always continues with
     the existing list of completions.  If this style is set to 'false',
     however, a new completion is started if the old list was generated
     by a different completion command; this is the behaviour without
     the _oldlist completer.

     For example, suppose you type ^Xc to generate a list of
     corrections, and menu completion is started in one of the usual
     ways.  Usually, or with this style set to 'false', typing TAB at
     this point would start trying to complete the line as it now
     appears.  With _oldlist, it instead continues to cycle through the
     list of corrections.

original
     This is used by the _approximate and _correct completers to decide
     if the original string should be added as a possible completion.
     Normally, this is done only if there are at least two possible
     corrections, but if this style is set to 'true', it is always
     added.  Note that the style will be examined with the completer
     field in the context name set to correct-NUM or approximate-NUM,
     where NUM is the number of errors that were accepted.

packageset
     This style is used when completing arguments of the Debian 'dpkg'
     program.  It contains an override for the default package set for a
     given context.  For example,

          zstyle ':completion:*:complete:dpkg:option--status-1:*' \
                         packageset avail

     causes available packages, rather than only installed packages, to
     be completed for 'dpkg --status'.

path
     The function that completes color names uses this style with the
     colors tag.  The value should be the pathname of a file containing
     color names in the format of an X11 rgb.txt file.  If the style is
     not set but this file is found in one of various standard locations
     it will be used as the default.

path-completion
     This is used by filename completion.  By default, filename
     completion examines all components of a path to see if there are
     completions of that component.  For example, /u/b/z can be
     completed to /usr/bin/zsh.  Explicitly setting this style to
     'false' inhibits this behaviour for path components up to the /
     before the cursor; this overrides the setting of accept-exact-dirs.

     Even with the style set to 'false', it is still possible to
     complete multiple paths by setting the option COMPLETE_IN_WORD and
     moving the cursor back to the first component in the path to be
     completed.  For example, /u/b/z can be completed to /usr/bin/zsh if
     the cursor is after the /u.

pine-directory
     If set, specifies the directory containing PINE mailbox files.
     There is no default, since recursively searching this directory is
     inconvenient for anyone who doesn't use PINE.

ports
     A list of Internet service names (network ports) to complete.  If
     this is not set, service names are taken from the file
     '/etc/services'.

prefix-hidden
     This is used for certain completions which share a common prefix,
     for example command options beginning with dashes.  If it is
     'true', the prefix will not be shown in the list of matches.

     The default value for this style is 'false'.

prefix-needed
     This style is also relevant for matches with a common prefix.  If
     it is set to 'true' this common prefix must be typed by the user to
     generate the matches.

     The style is applicable to the options, signals, jobs, functions,
     and parameters completion tags.

     For command options, this means that the initial '-', '+', or '--'
     must be typed explicitly before option names will be completed.

     For signals, an initial '-' is required before signal names will be
     completed.

     For jobs, an initial '%' is required before job names will be
     completed.

     For function and parameter names, an initial '_' or '.' is required
     before function or parameter names starting with those characters
     will be completed.

     The default value for this style is 'false' for function and
     parameter completions, and 'true' otherwise.

preserve-prefix
     This style is used when completing path names.  Its value should be
     a pattern matching an initial prefix of the word to complete that
     should be left unchanged under all circumstances.  For example, on
     some Unices an initial '//' (double slash) has a special meaning;
     setting this style to the string '//' will preserve it.  As another
     example, setting this style to '?:/' under Cygwin would allow
     completion after 'a:/...' and so on.

range
     This is used by the _history completer and the
     _history_complete_word bindable command to decide which words
     should be completed.

     If it is a single number, only the last N words from the history
     will be completed.

     If it is a range of the form 'MAX:SLICE', the last SLICE words will
     be completed; then if that yields no matches, the SLICE words
     before those will be tried and so on.  This process stops either
     when at least one match has been found, or MAX words have been
     tried.

     The default is to complete all words from the history at once.

recursive-files
     If this style is set, its value is an array of patterns to be
     tested against '$PWD/': note the trailing slash, which allows
     directories in the pattern to be delimited unambiguously by
     including slashes on both sides.  If an ordinary file completion
     fails and the word on the command line does not yet have a
     directory part to its name, the style is retrieved using the same
     tag as for the completion just attempted, then the elements tested
     against $PWD/ in turn.  If one matches, then the shell reattempts
     completion by prepending the word on the command line with each
     directory in the expansion of **/*(/) in turn.  Typically the
     elements of the style will be set to restrict the number of
     directories beneath the current one to a manageable number, for
     example '*/.git/*'.

     For example,

          zstyle ':completion:*' recursive-files '*/zsh/*'

     If the current directory is /home/pws/zsh/Src, then zle_tr<TAB> can
     be completed to Zle/zle_tricky.c.

regular
     This style is used by the _expand_alias completer and bindable
     command.  If set to 'true' (the default), regular aliases will be
     expanded but only in command position.  If it is set to 'false',
     regular aliases will never be expanded.  If it is set to 'always',
     regular aliases will be expanded even if not in command position.

rehash
     If this is set when completing external commands, the internal list
     (hash) of commands will be updated for each search by issuing the
     rehash command.  There is a speed penalty for this which is only
     likely to be noticeable when directories in the path have slow file
     access.

remote-access
     If set to 'false', certain commands will be prevented from making
     Internet connections to retrieve remote information.  This includes
     the completion for the CVS command.

     It is not always possible to know if connections are in fact to a
     remote site, so some may be prevented unnecessarily.

remove-all-dups
     The _history_complete_word bindable command and the _history
     completer use this to decide if all duplicate matches should be
     removed, rather than just consecutive duplicates.

select-prompt
     If this is set for the default tag, its value will be displayed
     during menu selection (see the menu style above) when the
     completion list does not fit on the screen as a whole.  The same
     escapes as for the list-prompt style are understood, except that
     the numbers refer to the match or line the mark is on.  A default
     prompt is used when the value is the empty string.

select-scroll
     This style is tested for the default tag and determines how a
     completion list is scrolled during a menu selection (see the menu
     style above) when the completion list does not fit on the screen as
     a whole.  If the value is '0' (zero), the list is scrolled by
     half-screenfuls; if it is a positive integer, the list is scrolled
     by the given number of lines; if it is a negative number, the list
     is scrolled by a screenful minus the absolute value of the given
     number of lines.  The default is to scroll by single lines.

separate-sections
     This style is used with the manuals tag when completing names of
     manual pages.  If it is 'true', entries for different sections are
     added separately using tag names of the form 'manuals.X', where X
     is the section number.  When the group-name style is also in
     effect, pages from different sections will appear separately.  This
     style is also used similarly with the words style when completing
     words for the dict command.  It allows words from different
     dictionary databases to be added separately.  See also
     insert-sections.

     The default for this style is 'false'.

show-ambiguity
     If the zsh/complist module is loaded, this style can be used to
     highlight the first ambiguous character in completion lists.  The
     value is either a color indication such as those supported by the
     list-colors style or, with a value of 'true', a default of
     underlining is selected.  The highlighting is only applied if the
     completion display strings correspond to the actual matches.

show-completer
     Tested whenever a new completer is tried.  If it is 'true', the
     completion system outputs a progress message in the listing area
     showing what completer is being tried.  The message will be
     overwritten by any output when completions are found and is removed
     after completion is finished.

single-ignored
     This is used by the _ignored completer when there is only one
     match.  If its value is 'show', the single match will be displayed
     but not inserted.  If the value is 'menu', then the single match
     and the original string are both added as matches and menu
     completion is started, making it easy to select either of them.

sort
     This allows the standard ordering of matches to be overridden.

     If its value is 'true' or 'false', sorting is enabled or disabled.
     Additionally the values associated with the '-o' option to compadd
     can also be listed: match, nosort, numeric, reverse.  If it is not
     set for the context, the standard behaviour of the calling widget
     is used.

     The style is tested first against the full context including the
     tag, and if that fails to produce a value against the context
     without the tag.

     In many cases where a calling widget explicitly selects a
     particular ordering in lieu of the default, a value of 'true' is
     not honoured.  An example of where this is not the case is for
     command history where the default of sorting matches
     chronologically may be overridden by setting the style to 'true'.

     In the _expand completer, if it is set to 'true', the expansions
     generated will always be sorted.  If it is set to 'menu', then the
     expansions are only sorted when they are offered as single strings
     but not in the string containing all possible expansions.

special-dirs
     Normally, the completion code will not produce the directory names
     '.' and '..' as possible completions.  If this style is set to
     'true', it will add both '.' and '..' as possible completions; if
     it is set to '..', only '..' will be added.

     The following example sets special-dirs to '..' when the current
     prefix is empty, is a single '.', or consists only of a path
     beginning with '../'.  Otherwise the value is 'false'.

          zstyle -e ':completion:*' special-dirs \
             '[[ $PREFIX = (../)#(|.|..) ]] && reply=(..)'

squeeze-slashes
     If set to 'true', sequences of slashes in filename paths (for
     example in 'foo//bar') will be treated as a single slash.  This is
     the usual behaviour of UNIX paths.  However, by default the file
     completion function behaves as if there were a '*' between the
     slashes.

stop
     If set to 'true', the _history_complete_word bindable command will
     stop once when reaching the beginning or end of the history.
     Invoking _history_complete_word will then wrap around to the
     opposite end of the history.  If this style is set to 'false' (the
     default), _history_complete_word will loop immediately as in a menu
     completion.

strip-comments
     If set to 'true', this style causes non-essential comment text to
     be removed from completion matches.  Currently it is only used when
     completing e-mail addresses where it removes any display name from
     the addresses, cutting them down to plain USER@HOST form.

subst-globs-only
     This is used by the _expand completer.  If it is set to 'true', the
     expansion will only be used if it resulted from globbing; hence, if
     expansions resulted from the use of the substitute style described
     below, but these were not further changed by globbing, the
     expansions will be rejected.

     The default for this style is 'false'.

substitute
     This boolean style controls whether the _expand completer will
     first try to expand all substitutions in the string (such as
     '$(...)' and '${...}').

     The default is 'true'.

suffix
     This is used by the _expand completer if the word starts with a
     tilde or contains a parameter expansion.  If it is set to 'true',
     the word will only be expanded if it doesn't have a suffix, i.e.
     if it is something like '~foo' or '$foo' rather than '~foo/' or
     '$foo/bar', unless that suffix itself contains characters eligible
     for expansion.  The default for this style is 'true'.

tag-order
     This provides a mechanism for sorting how the tags available in a
     particular context will be used.

     The values for the style are sets of space-separated lists of tags.
     The tags in each value will be tried at the same time; if no match
     is found, the next value is used.  (See the file-patterns style for
     an exception to this behavior.)

     For example:

          zstyle ':completion:*:complete:-command-:*:*' tag-order \
              'commands functions'

     specifies that completion in command position first offers external
     commands and shell functions.  Remaining tags will be tried if no
     completions are found.

     In addition to tag names, each string in the value may take one of
     the following forms:

     -
          If any value consists of only a hyphen, then _only_ the tags
          specified in the other values are generated.  Normally all
          tags not explicitly selected are tried last if the specified
          tags fail to generate any matches.  This means that a single
          value consisting only of a single hyphen turns off completion.

     ! TAGS...
          A string starting with an exclamation mark specifies names of
          tags that are _not_ to be used.  The effect is the same as if
          all other possible tags for the context had been listed.

     TAG:LABEL ...
          Here, TAG is one of the standard tags and LABEL is an
          arbitrary name.  Matches are generated as normal but the name
          LABEL is used in contexts instead of TAG.  This is not useful
          in words starting with !.

          If the LABEL starts with a hyphen, the TAG is prepended to the
          LABEL to form the name used for lookup.  This can be used to
          make the completion system try a certain tag more than once,
          supplying different style settings for each attempt; see below
          for an example.

     TAG:LABEL:DESCRIPTION
          As before, but description will replace the '%d' in the value
          of the format style instead of the default description
          supplied by the completion function.  Spaces in the
          description must be quoted with a backslash.  A '%d' appearing
          in DESCRIPTION is replaced with the description given by the
          completion function.

     In any of the forms above the tag may be a pattern or several
     patterns in the form '{PAT1,PAT2...}'.  In this case all matching
     tags will be used except for any given explicitly in the same
     string.

     One use of these features is to try one tag more than once, setting
     other styles differently on each attempt, but still to use all the
     other tags without having to repeat them all.  For example, to make
     completion of function names in command position ignore all the
     completion functions starting with an underscore the first time
     completion is tried:

          zstyle ':completion:*:*:-command-:*:*' tag-order \
              'functions:-non-comp *' functions
          zstyle ':completion:*:functions-non-comp' \
              ignored-patterns '_*'

     On the first attempt, all tags will be offered but the functions
     tag will be replaced by functions-non-comp.  The ignored-patterns
     style is set for this tag to exclude functions starting with an
     underscore.  If there are no matches, the second value of the
     tag-order style is used which completes functions using the default
     tag, this time presumably including all function names.

     The matches for one tag can be split into different groups.  For
     example:

          zstyle ':completion:*' tag-order \
              'options:-long:long\ options
               options:-short:short\ options
               options:-single-letter:single\ letter\ options'
          zstyle ':completion:*:options-long' \
               ignored-patterns '[-+](|-|[^-]*)'
          zstyle ':completion:*:options-short' \
               ignored-patterns '--*' '[-+]?'
          zstyle ':completion:*:options-single-letter' \
               ignored-patterns '???*'

     With the group-names style set, options beginning with '--',
     options beginning with a single '-' or '+' but containing multiple
     characters, and single-letter options will be displayed in separate
     groups with different descriptions.

     Another use of patterns is to try multiple match specifications one
     after another.  The matcher-list style offers something similar,
     but it is tested very early in the completion system and hence
     can't be set for single commands nor for more specific contexts.
     Here is how to try normal completion without any match
     specification and, if that generates no matches, try again with
     case-insensitive matching, restricting the effect to arguments of
     the command foo:

          zstyle ':completion:*:*:foo:*:*' tag-order '*' '*:-case'
          zstyle ':completion:*-case' matcher 'm:{a-z}={A-Z}'

     First, all the tags offered when completing after foo are tried
     using the normal tag name.  If that generates no matches, the
     second value of tag-order is used, which tries all tags again
     except that this time each has -case appended to its name for
     lookup of styles.  Hence this time the value for the matcher style
     from the second call to zstyle in the example is used to make
     completion case-insensitive.

     It is possible to use the -e option of the zstyle builtin command
     to specify conditions for the use of particular tags.  For example:

          zstyle -e '*:-command-:*' tag-order '
              if [[ -n $PREFIX$SUFFIX ]]; then
                reply=( )
              else
                reply=( - )
              fi'

     Completion in command position will be attempted only if the string
     typed so far is not empty.  This is tested using the PREFIX special
     parameter; see *note Completion Widgets:: for a description of
     parameters which are special inside completion widgets.  Setting
     reply to an empty array provides the default behaviour of trying
     all tags at once; setting it to an array containing only a hyphen
     disables the use of all tags and hence of all completions.

     If no tag-order style has been defined for a context, the strings
     '(|*-)argument-* (|*-)option-* values' and 'options' plus all tags
     offered by the completion function will be used to provide a
     sensible default behavior that causes arguments (whether normal
     command arguments or arguments of options) to be completed before
     option names for most commands.

urls
     This is used together with the urls tag by functions completing
     URLs.

     If the value consists of more than one string, or if the only
     string does not name a file or directory, the strings are used as
     the URLs to complete.

     If the value contains only one string which is the name of a normal
     file the URLs are taken from that file (where the URLs may be
     separated by white space or newlines).

     Finally, if the only string in the value names a directory, the
     directory hierarchy rooted at this directory gives the completions.
     The top level directory should be the file access method, such as
     'http', 'ftp', 'bookmark' and so on.  In many cases the next level
     of directories will be a filename.  The directory hierarchy can
     descend as deep as necessary.

     For example,

          zstyle ':completion:*' urls ~/.urls
          mkdir -p ~/.urls/ftp/ftp.zsh.org/pub

     allows completion of all the components of the URL
     ftp://ftp.zsh.org/pub after suitable commands such as 'netscape' or
     'lynx'.  Note, however, that access methods and files are completed
     separately, so if the hosts style is set hosts can be completed
     without reference to the urls style.

     See the description in the function _urls itself for more
     information (e.g.  'more $^fpath/_urls(N)').

use-cache
     If this is set, the completion caching layer is activated for any
     completions which use it (via the _store_cache, _retrieve_cache,
     and _cache_invalid functions).  The directory containing the cache
     files can be changed with the cache-path style.

use-compctl
     If this style is set to a string _not_ equal to false, 0, no, and
     off, the completion system may use any completion specifications
     defined with the compctl builtin command.  If the style is unset,
     this is done only if the zsh/compctl module is loaded.  The string
     may also contain the substring 'first' to use completions defined
     with 'compctl -T', and the substring 'default' to use the
     completion defined with 'compctl -D'.

     Note that this is only intended to smooth the transition from
     compctl to the new completion system and may disappear in the
     future.

     Note also that the definitions from compctl will only be used if
     there is no specific completion function for the command in
     question.  For example, if there is a function _foo to complete
     arguments to the command foo, compctl will never be invoked for
     foo.  However, the compctl version will be tried if foo only uses
     default completion.

use-ip
     By default, the function _hosts that completes host names strips IP
     addresses from entries read from host databases such as NIS and ssh
     files.  If this style is 'true', the corresponding IP addresses can
     be completed as well.  This style is not use in any context where
     the hosts style is set; note also it must be set before the cache
     of host names is generated (typically the first completion
     attempt).

users
     This may be set to a list of usernames to be completed.  If it is
     not set all usernames will be completed.  Note that if it is set
     only that list of users will be completed; this is because on some
     systems querying all users can take a prohibitive amount of time.

users-hosts
     The values of this style should be of the form 'USER@HOST' or
     'USER:HOST'.  It is used for commands that need pairs of user- and
     hostnames.  These commands will complete usernames from this style
     (only), and will restrict subsequent hostname completion to hosts
     paired with that user in one of the values of the style.

     It is possible to group values for sets of commands which allow a
     remote login, such as rlogin and ssh, by using the my-accounts tag.
     Similarly, values for sets of commands which usually refer to the
     accounts of other people, such as talk and finger, can be grouped
     by using the other-accounts tag.  More ambivalent commands may use
     the accounts tag.

users-hosts-ports
     Like users-hosts but used for commands like telnet and containing
     strings of the form 'USER@HOST:PORT'.

verbose
     If set, as it is by default, the completion listing is more
     verbose.  In particular many commands show descriptions for options
     if this style is 'true'.

word
     This is used by the _list completer, which prevents the insertion
     of completions until a second completion attempt when the line has
     not changed.  The normal way of finding out if the line has changed
     is to compare its entire contents between the two occasions.  If
     this style is 'true', the comparison is instead performed only on
     the current word.  Hence if completion is performed on another word
     with the same contents, completion will not be delayed.


File: zsh.info,  Node: Control Functions,  Next: Bindable Commands,  Prev: Completion System Configuration,  Up: Completion System

20.4 Control Functions
======================

The initialization script compinit redefines all the widgets which
perform completion to call the supplied widget function _main_complete.
This function acts as a wrapper calling the so-called 'completer'
functions that generate matches.  If _main_complete is called with
arguments, these are taken as the names of completer functions to be
called in the order given.  If no arguments are given, the set of
functions to try is taken from the completer style.  For example, to use
normal completion and correction if that doesn't generate any matches:

     zstyle ':completion:*' completer _complete _correct

after calling compinit.  The default value for this style is '_complete
_ignored', i.e.  normally only ordinary completion is tried, first with
the effect of the ignored-patterns style and then without it.  The
_main_complete function uses the return status of the completer
functions to decide if other completers should be called.  If the return
status is zero, no other completers are tried and the _main_complete
function returns.

If the first argument to _main_complete is a single hyphen, the
arguments will not be taken as names of completers.  Instead, the second
argument gives a name to use in the COMPLETER field of the context and
the other arguments give a command name and arguments to call to
generate the matches.

The following completer functions are contained in the distribution,
although users may write their own.  Note that in contexts the leading
underscore is stripped, for example basic completion is performed in the
context ':completion::complete:...'.

_all_matches
     This completer can be used to add a string consisting of all other
     matches.  As it influences later completers it must appear as the
     first completer in the list.  The list of all matches is affected
     by the avoid-completer and old-matches styles described above.

     It may be useful to use the _generic function described below to
     bind _all_matches to its own keystroke, for example:

          zle -C all-matches complete-word _generic
          bindkey '^Xa' all-matches
          zstyle ':completion:all-matches:*' old-matches only
          zstyle ':completion:all-matches::::' completer _all_matches

     Note that this does not generate completions by itself: first use
     any of the standard ways of generating a list of completions, then
     use ^Xa to show all matches.  It is possible instead to add a
     standard completer to the list and request that the list of all
     matches should be directly inserted:

          zstyle ':completion:all-matches::::' completer \
                 _all_matches _complete
          zstyle ':completion:all-matches:*' insert true

     In this case the old-matches style should not be set.

_approximate
     This is similar to the basic _complete completer but allows the
     completions to undergo corrections.  The maximum number of errors
     can be specified by the max-errors style; see the description of
     approximate matching in *note Filename Generation:: for how errors
     are counted.  Normally this completer will only be tried after the
     normal _complete completer:

          zstyle ':completion:*' completer _complete _approximate

     This will give correcting completion if and only if normal
     completion yields no possible completions.  When corrected
     completions are found, the completer will normally start menu
     completion allowing you to cycle through these strings.

     This completer uses the tags corrections and original when
     generating the possible corrections and the original string.  The
     format style for the former may contain the additional sequences
     '%e' and '%o' which will be replaced by the number of errors
     accepted to generate the corrections and the original string,
     respectively.

     The completer progressively increases the number of errors allowed
     up to the limit by the max-errors style, hence if a completion is
     found with one error, no completions with two errors will be shown,
     and so on.  It modifies the completer name in the context to
     indicate the number of errors being tried: on the first try the
     completer field contains 'approximate-1', on the second try
     'approximate-2', and so on.

     When _approximate is called from another function, the number of
     errors to accept may be passed with the -a option.  The argument is
     in the same format as the max-errors style, all in one string.

     Note that this completer (and the _correct completer mentioned
     below) can be quite expensive to call, especially when a large
     number of errors are allowed.  One way to avoid this is to set up
     the completer style using the -e option to zstyle so that some
     completers are only used when completion is attempted a second time
     on the same string, e.g.:

          zstyle -e ':completion:*' completer '
            if [[ $_last_try != "$HISTNO$BUFFER$CURSOR" ]]; then
              _last_try="$HISTNO$BUFFER$CURSOR"
              reply=(_complete _match _prefix)
            else
              reply=(_ignored _correct _approximate)
            fi'

     This uses the HISTNO parameter and the BUFFER and CURSOR special
     parameters that are available inside zle and completion widgets to
     find out if the command line hasn't changed since the last time
     completion was tried.  Only then are the _ignored, _correct and
     _approximate completers called.

_canonical_paths [ -A VAR ] [ -N ] [ -MJV12nfX ] TAG DESCR [ PATHS ... ]
     This completion function completes all paths given to it, and also
     tries to offer completions which point to the same file as one of
     the paths given (relative path when an absolute path is given, and
     vice versa; when ..'s are present in the word to be completed; and
     some paths got from symlinks).

     -A, if specified, takes the paths from the array variable
     specified.  Paths can also be specified on the command line as
     shown above.  -N, if specified, prevents canonicalizing the paths
     given before using them for completion, in case they are already
     so.  The options -M, -J, -V, -1, -2, -n, -F, -X are passed to
     compadd.

     See _description for a description of TAG and DESCR.

_cmdambivalent
     Completes the remaining positional arguments as an external
     command.  The external command and its arguments are completed as
     separate arguments (in a manner appropriate for completing
     /usr/bin/env) if there are two or more remaining positional
     arguments on the command line, and as a quoted command string (in
     the manner of system(...)) otherwise.  See also _cmdstring and
     _precommand.

     This function takes no arguments.

_cmdstring
     Completes an external command as a single argument, as for
     system(...).

_complete
     This completer generates all possible completions in a
     context-sensitive manner, i.e.  using the settings defined with the
     compdef function explained above and the current settings of all
     special parameters.  This gives the normal completion behaviour.

     To complete arguments of commands, _complete uses the utility
     function _normal, which is in turn responsible for finding the
     particular function; it is described below.  Various contexts of
     the form -CONTEXT- are handled specifically.  These are all
     mentioned above as possible arguments to the #compdef tag.

     Before trying to find a function for a specific context, _complete
     checks if the parameter 'compcontext' is set.  Setting
     'compcontext' allows the usual completion dispatching to be
     overridden which is useful in places such as a function that uses
     vared for input.  If it is set to an array, the elements are taken
     to be the possible matches which will be completed using the tag
     'values' and the description 'value'.  If it is set to an
     associative array, the keys are used as the possible completions
     and the values (if non-empty) are used as descriptions for the
     matches.  If 'compcontext' is set to a string containing colons, it
     should be of the form 'TAG:DESCR:ACTION'.  In this case the TAG and
     DESCR give the tag and description to use and the ACTION indicates
     what should be completed in one of the forms accepted by the
     _arguments utility function described below.

     Finally, if 'compcontext' is set to a string without colons, the
     value is taken as the name of the context to use and the function
     defined for that context will be called.  For this purpose, there
     is a special context named -command-line- that completes whole
     command lines (commands and their arguments).  This is not used by
     the completion system itself but is nonetheless handled when
     explicitly called.

_correct
     Generate corrections, but not completions, for the current word;
     this is similar to _approximate but will not allow any number of
     extra characters at the cursor as that completer does.  The effect
     is similar to spell-checking.  It is based on _approximate, but the
     completer field in the context name is correct.

     For example, with:

          zstyle ':completion:::::' completer \
                 _complete _correct _approximate
          zstyle ':completion:*:correct:::' max-errors 2 not-numeric
          zstyle ':completion:*:approximate:::' max-errors 3 numeric

     correction will accept up to two errors.  If a numeric argument is
     given, correction will not be performed, but correcting completion
     will be, and will accept as many errors as given by the numeric
     argument.  Without a numeric argument, first correction and then
     correcting completion will be tried, with the first one accepting
     two errors and the second one accepting three errors.

     When _correct is called as a function, the number of errors to
     accept may be given following the -a option.  The argument is in
     the same form a values to the accept style, all in one string.

     This completer function is intended to be used without the
     _approximate completer or, as in the example, just before it.
     Using it after the _approximate completer is useless since
     _approximate will at least generate the corrected strings generated
     by the _correct completer -- and probably more.

_expand
     This completer function does not really perform completion, but
     instead checks if the word on the command line is eligible for
     expansion and, if it is, gives detailed control over how this
     expansion is done.  For this to happen, the completion system needs
     to be invoked with complete-word, not expand-or-complete (the
     default binding for TAB), as otherwise the string will be expanded
     by the shell's internal mechanism before the completion system is
     started.  Note also this completer should be called before the
     _complete completer function.

     The tags used when generating expansions are all-expansions for the
     string containing all possible expansions, expansions when adding
     the possible expansions as single matches and original when adding
     the original string from the line.  The order in which these
     strings are generated, if at all, can be controlled by the
     group-order and tag-order styles, as usual.

     The format string for all-expansions and for expansions may contain
     the sequence '%o' which will be replaced by the original string
     from the line.

     The kind of expansion to be tried is controlled by the substitute,
     glob and subst-globs-only styles.

     It is also possible to call _expand as a function, in which case
     the different modes may be selected with options: -s for
     substitute, -g for glob and -o for subst-globs-only.

_expand_alias
     If the word the cursor is on is an alias, it is expanded and no
     other completers are called.  The types of aliases which are to be
     expanded can be controlled with the styles regular, global and
     disabled.

     This function is also a bindable command, see *note Bindable
     Commands::.

_extensions
     If the cursor follows the string '*.', filename extensions are
     completed.  The extensions are taken from files in current
     directory or a directory specified at the beginning of the current
     word.  For exact matches, completion continues to allow other
     completers such as _expand to expand the pattern.  The standard
     add-space and prefix-hidden styles are observed.

_external_pwds
     Completes current directories of other zsh processes belonging to
     the current user.

     This is intended to be used via _generic, bound to a custom key
     combination.  Note that pattern matching is enabled so matching is
     performed similar to how it works with the _match completer.

_history
     Complete words from the shell's command history.  This completer
     can be controlled by the remove-all-dups, and sort styles as for
     the _history_complete_word bindable command, see *note Bindable
     Commands:: and *note Completion System Configuration::.

_ignored
     The ignored-patterns style can be set to a list of patterns which
     are compared against possible completions; matching ones are
     removed.  With this completer those matches can be reinstated, as
     if no ignored-patterns style were set.  The completer actually
     generates its own list of matches; which completers are invoked is
     determined in the same way as for the _prefix completer.  The
     single-ignored style is also available as described above.

_list
     This completer allows the insertion of matches to be delayed until
     completion is attempted a second time without the word on the line
     being changed.  On the first attempt, only the list of matches will
     be shown.  It is affected by the styles condition and word, see
     *note Completion System Configuration::.

_match
     This completer is intended to be used after the _complete
     completer.  It behaves similarly but the string on the command line
     may be a pattern to match against trial completions.  This gives
     the effect of the GLOB_COMPLETE option.

     Normally completion will be performed by taking the pattern from
     the line, inserting a '*' at the cursor position and comparing the
     resulting pattern with the possible completions generated.  This
     can be modified with the match-original style described above.

     The generated matches will be offered in a menu completion unless
     the insert-unambiguous style is set to 'true'; see the description
     above for other options for this style.

     Note that matcher specifications defined globally or used by the
     completion functions (the styles matcher-list and matcher) will not
     be used.

_menu
     This completer was written as simple example function to show how
     menu completion can be enabled in shell code.  However, it has the
     notable effect of disabling menu selection which can be useful with
     _generic based widgets.  It should be used as the first completer
     in the list.  Note that this is independent of the setting of the
     MENU_COMPLETE option and does not work with the other menu
     completion widgets such as reverse-menu-complete, or
     accept-and-menu-complete.

_oldlist
     This completer controls how the standard completion widgets behave
     when there is an existing list of completions which may have been
     generated by a special completion (i.e.  a separately-bound
     completion command).  It allows the ordinary completion keys to
     continue to use the list of completions thus generated, instead of
     producing a new list of ordinary contextual completions.  It should
     appear in the list of completers before any of the widgets which
     generate matches.  It uses two styles: old-list and old-menu, see
     *note Completion System Configuration::.

_precommand
     Complete an external command in word-separated arguments, as for
     exec and /usr/bin/env.

_prefix
     This completer can be used to try completion with the suffix
     (everything after the cursor) ignored.  In other words, the suffix
     will not be considered to be part of the word to complete.  The
     effect is similar to the expand-or-complete-prefix command.

     The completer style is used to decide which other completers are to
     be called to generate matches.  If this style is unset, the list of
     completers set for the current context is used -- except, of
     course, the _prefix completer itself.  Furthermore, if this
     completer appears more than once in the list of completers only
     those completers not already tried by the last invocation of
     _prefix will be called.

     For example, consider this global completer style:

          zstyle ':completion:*' completer \
              _complete _prefix _correct _prefix:foo

     Here, the _prefix completer tries normal completion but ignoring
     the suffix.  If that doesn't generate any matches, and neither does
     the call to the _correct completer after it, _prefix will be called
     a second time and, now only trying correction with the suffix
     ignored.  On the second invocation the completer part of the
     context appears as 'foo'.

     To use _prefix as the last resort and try only normal completion
     when it is invoked:

          zstyle ':completion:*' completer _complete ... _prefix
          zstyle ':completion::prefix:*' completer _complete

     The add-space style is also respected.  If it is set to 'true' then
     _prefix will insert a space between the matches generated (if any)
     and the suffix.

     Note that this completer is only useful if the COMPLETE_IN_WORD
     option is set; otherwise, the cursor will be moved to the end of
     the current word before the completion code is called and hence
     there will be no suffix.

_user_expand
     This completer behaves similarly to the _expand completer but
     instead performs expansions defined by users.  The styles add-space
     and sort styles specific to the _expand completer are usable with
     _user_expand in addition to other styles handled more generally by
     the completion system.  The tag all-expansions is also available.

     The expansion depends on the array style user-expand being defined
     for the current context; remember that the context for completers
     is less specific than that for contextual completion as the full
     context has not yet been determined.  Elements of the array may
     have one of the following forms:

     $HASH

          HASH is the name of an associative array.  Note this is not a
          full parameter expression, merely a $, suitably quoted to
          prevent immediate expansion, followed by the name of an
          associative array.  If the trial expansion word matches a key
          in HASH, the resulting expansion is the corresponding value.

     _FUNC

          _FUNC is the name of a shell function whose name must begin
          with _ but is not otherwise special to the completion system.
          The function is called with the trial word as an argument.  If
          the word is to be expanded, the function should set the array
          reply to a list of expansions.  Optionally, it can set REPLY
          to a word that will be used as a description for the set of
          expansions.  The return status of the function is irrelevant.


File: zsh.info,  Node: Bindable Commands,  Next: Completion Functions,  Prev: Control Functions,  Up: Completion System

20.5 Bindable Commands
======================

In addition to the context-dependent completions provided, which are
expected to work in an intuitively obvious way, there are a few widgets
implementing special behaviour which can be bound separately to keys.
The following is a list of these and their default bindings.

_bash_completions
     This function is used by two widgets, _bash_complete-word and
     _bash_list-choices.  It exists to provide compatibility with
     completion bindings in bash.  The last character of the binding
     determines what is completed: '!', command names; '$', environment
     variables; '@', host names; '/', file names; '~' user names.  In
     bash, the binding preceded by '\e' gives completion, and preceded
     by '^X' lists options.  As some of these bindings clash with
     standard zsh bindings, only '\e~' and '^X~' are bound by default.
     To add the rest, the following should be added to .zshrc after
     compinit has been run:

          for key in '!' '$' '@' '/' '~'; do
            bindkey "\e$key" _bash_complete-word
            bindkey "^X$key" _bash_list-choices
          done

     This includes the bindings for '~' in case they were already bound
     to something else; the completion code does not override user
     bindings.

_correct_filename (^XC)
     Correct the filename path at the cursor position.  Allows up to six
     errors in the name.  Can also be called with an argument to correct
     a filename path, independently of zle; the correction is printed on
     standard output.

_correct_word (^Xc)
     Performs correction of the current argument using the usual
     contextual completions as possible choices.  This stores the string
     'correct-word' in the FUNCTION field of the context name and then
     calls the _correct completer.

_expand_alias (^Xa)
     This function can be used as a completer and as a bindable command.
     It expands the word the cursor is on if it is an alias.  The types
     of alias expanded can be controlled with the styles regular, global
     and disabled.

     When used as a bindable command there is one additional feature
     that can be selected by setting the complete style to 'true'.  In
     this case, if the word is not the name of an alias, _expand_alias
     tries to complete the word to a full alias name without expanding
     it.  It leaves the cursor directly after the completed word so that
     invoking _expand_alias once more will expand the now-complete alias
     name.

_expand_word (^Xe)
     Performs expansion on the current word: equivalent to the standard
     expand-word command, but using the _expand completer.  Before
     calling it, the FUNCTION field of the context is set to
     'expand-word'.

_generic
     This function is not defined as a widget and not bound by default.
     However, it can be used to define a widget and will then store the
     name of the widget in the FUNCTION field of the context and call
     the completion system.  This allows custom completion widgets with
     their own set of style settings to be defined easily.  For example,
     to define a widget that performs normal completion and starts menu
     selection:

          zle -C foo complete-word _generic
          bindkey '...' foo
          zstyle ':completion:foo:*' menu yes select=1

     Note in particular that the completer style may be set for the
     context in order to change the set of functions used to generate
     possible matches.  If _generic is called with arguments, those are
     passed through to _main_complete as the list of completers in place
     of those defined by the completer style.

_history_complete_word (\e/)
     Complete words from the shell's command history.  This uses the
     list, remove-all-dups, sort, and stop styles.

_most_recent_file (^Xm)
     Complete the name of the most recently modified file matching the
     pattern on the command line (which may be blank).  If given a
     numeric argument N, complete the Nth most recently modified file.
     Note the completion, if any, is always unique.

_next_tags (^Xn)
     This command alters the set of matches used to that for the next
     tag, or set of tags, either as given by the tag-order style or as
     set by default; these matches would otherwise not be available.
     Successive invocations of the command cycle through all possible
     sets of tags.

_read_comp (^X^R)
     Prompt the user for a string, and use that to perform completion on
     the current word.  There are two possibilities for the string.
     First, it can be a set of words beginning '_', for example '_files
     -/', in which case the function with any arguments will be called
     to generate the completions.  Unambiguous parts of the function
     name will be completed automatically (normal completion is not
     available at this point) until a space is typed.

     Second, any other string will be passed as a set of arguments to
     compadd and should hence be an expression specifying what should be
     completed.

     A very restricted set of editing commands is available when reading
     the string: 'DEL' and '^H' delete the last character; '^U' deletes
     the line, and '^C' and '^G' abort the function, while 'RET' accepts
     the completion.  Note the string is used verbatim as a command
     line, so arguments must be quoted in accordance with standard shell
     rules.

     Once a string has been read, the next call to _read_comp will use
     the existing string instead of reading a new one.  To force a new
     string to be read, call _read_comp with a numeric argument.

_complete_debug (^X?)
     This widget performs ordinary completion, but captures in a
     temporary file a trace of the shell commands executed by the
     completion system.  Each completion attempt gets its own file.  A
     command to view each of these files is pushed onto the editor
     buffer stack.

_complete_help (^Xh)
     This widget displays information about the context names, the tags,
     and the completion functions used when completing at the current
     cursor position.  If given a numeric argument other than 1 (as in
     'ESC-2 ^Xh'), then the styles used and the contexts for which they
     are used will be shown, too.

     Note that the information about styles may be incomplete; it
     depends on the information available from the completion functions
     called, which in turn is determined by the user's own styles and
     other settings.

_complete_help_generic
     Unlike other commands listed here, this must be created as a normal
     ZLE widget rather than a completion widget (i.e.  with zle -N).  It
     is used for generating help with a widget bound to the _generic
     widget that is described above.

     If this widget is created using the name of the function, as it is
     by default, then when executed it will read a key sequence.  This
     is expected to be bound to a call to a completion function that
     uses the _generic widget.  That widget will be executed, and
     information provided in the same format that the _complete_help
     widget displays for contextual completion.

     If the widget's name contains debug, for example if it is created
     as 'zle -N _complete_debug_generic _complete_help_generic', it will
     read and execute the keystring for a generic widget as before, but
     then generate debugging information as done by _complete_debug for
     contextual completion.

     If the widget's name contains noread, it will not read a keystring
     but instead arrange that the next use of a generic widget run in
     the same shell will have the effect as described above.

     The widget works by setting the shell parameter
     ZSH_TRACE_GENERIC_WIDGET which is read by _generic.  Unsetting the
     parameter cancels any pending effect of the noread form.

     For example, after executing the following:

          zle -N _complete_debug_generic _complete_help_generic
          bindkey '^x:' _complete_debug_generic

     typing 'C-x :' followed by the key sequence for a generic widget
     will cause trace output for that widget to be saved to a file.

_complete_tag (^Xt)
     This widget completes symbol tags created by the etags or ctags
     programmes (note there is no connection with the completion
     system's tags) stored in a file TAGS, in the format used by etags,
     or tags, in the format created by ctags.  It will look back up the
     path hierarchy for the first occurrence of either file; if both
     exist, the file TAGS is preferred.  You can specify the full path
     to a TAGS or tags file by setting the parameter $TAGSFILE or
     $tagsfile respectively.  The corresponding completion tags used are
     etags and vtags, after emacs and vi respectively.


File: zsh.info,  Node: Completion Functions,  Next: Completion System Variables,  Prev: Bindable Commands,  Up: Completion System

20.6 Utility Functions
======================

Descriptions follow for utility functions that may be useful when
writing completion functions.  If functions are installed in
subdirectories, most of these reside in the Base subdirectory.  Like the
example functions for commands in the distribution, the utility
functions generating matches all follow the convention of returning
status zero if they generated completions and non-zero if no matching
completions could be added.

_absolute_command_paths
     This function completes external commands as absolute paths (unlike
     _command_names -e which completes their basenames).  It takes no
     arguments.

_all_labels [ -x ] [ -12VJ ] TAG NAME DESCR [ COMMAND ARG ... ]
     This is a convenient interface to the _next_label function below,
     implementing the loop shown in the _next_label example.  The
     COMMAND and its arguments are called to generate the matches.  The
     options stored in the parameter NAME will automatically be inserted
     into the ARGs passed to the COMMAND.  Normally, they are put
     directly after the COMMAND, but if one of the ARGs is a single
     hyphen, they are inserted directly before that.  If the hyphen is
     the last argument, it will be removed from the argument list before
     the COMMAND is called.  This allows _all_labels to be used in
     almost all cases where the matches can be generated by a single
     call to the compadd builtin command or by a call to one of the
     utility functions.

     For example:

          local expl
          ...
          if _requested foo; then
            ...
            _all_labels foo expl '...' compadd ... - $matches
          fi

     Will complete the strings from the matches parameter, using compadd
     with additional options which will take precedence over those
     generated by _all_labels.

_alternative [ -O NAME ] [ -C NAME ] SPEC ...
     This function is useful in simple cases where multiple tags are
     available.  Essentially it implements a loop like the one described
     for the _tags function below.

     The tags to use and the action to perform if a tag is requested are
     described using the SPECs which are of the form:
     'TAG:DESCR:ACTION'.  The TAGs are offered using _tags and if the
     tag is requested, the ACTION is executed with the given description
     DESCR.  The ACTIONs are those accepted by the _arguments function
     (described below), with the following exceptions:

        • The '->STATE' and '=...' forms are not supported.

        • The '((a\:bar b\:baz))' form does not need the colon to be
          escaped, since the SPECs have no colon-separated fields after
          the ACTION.

     For example, the ACTION may be a simple function call:

          _alternative \
              'users:user:_users' \
              'hosts:host:_hosts'

     offers usernames and hostnames as possible matches, generated by
     the _users and _hosts functions respectively.

     Like _arguments, this function uses _all_labels to execute the
     actions, which will loop over all sets of tags.  Special handling
     is only required if there is an additional valid tag, for example
     inside a function called from _alternative.

     The option '-O NAME' is used in the same way as by the _arguments
     function.  In other words, the elements of the NAME array will be
     passed to compadd when executing an action.

     Like _tags this function supports the -C option to give a different
     name for the argument context field.

_arguments [ -nswWCRS ] [ -A PAT ] [ -O NAME ] [ -M MATCHSPEC ]
           [ : ] SPEC ...
_arguments [ OPT ... ] -- [ -l ] [ -i PATS ] [ -s PAIR ]
           [ HELPSPEC ...]
     This function can be used to give a complete specification for
     completion for a command whose arguments follow standard UNIX
     option and argument conventions.

     _Options Overview_

     Options to _arguments itself must be in separate words, i.e.  -s
     -w, not -sw.  The options are followed by SPECs that describe
     options and arguments of the analyzed command.  To avoid ambiguity,
     all options to _arguments itself may be separated from the SPEC
     forms by a single colon.

     The '--' form is used to intuit SPEC forms from the help output of
     the command being analyzed, and is described in detail below.  The
     OPTS for the '--' form are otherwise the same options as the first
     form.  Note that '-s' following '--' has a distinct meaning from
     '-s' preceding '--', and both may appear.

     The option switches -s, -S, -A, -w, and -W affect how _arguments
     parses the analyzed command line's options.  These switches are
     useful for commands with standard argument parsing.

     The options of _arguments have the following meanings:

     -n
          With this option, _arguments sets the parameter NORMARG to the
          position of the first normal argument in the $words array,
          i.e.  the position after the end of the options.  If that
          argument has not been reached, NORMARG is set to -1.  The
          caller should declare 'integer NORMARG' if the -n option is
          passed; otherwise the parameter is not used.

     -s
          Enable _option stacking_ for single-letter options, whereby
          multiple single-letter options may be combined into a single
          word.  For example, the two options '-x' and '-y' may be
          combined into a single word '-xy'.  By default, every word
          corresponds to a single option name ('-xy' is a single option
          named 'xy').

          Options beginning with a single hyphen or plus sign are
          eligible for stacking; words beginning with two hyphens are
          not.

          Note that -s after -- has a different meaning, which is
          documented in the segment entitled 'Deriving SPEC forms from
          the help output'.

     -w
          In combination with -s, allow option stacking even if one or
          more of the options take arguments.  For example, if -x takes
          an argument, with no -s, '-xy' is considered as a single
          (unhandled) option; with -s, -xy is an option with the
          argument 'y'; with both -s and -w, -xy is the option -x and
          the option -y with arguments to -x (and to -y, if it takes
          arguments) still to come in subsequent words.

     -W
          This option takes -w a stage further: it is possible to
          complete single-letter options even after an argument that
          occurs in the same word.  However, it depends on the action
          performed whether options will really be completed at this
          point.  For more control, use a utility function like _guard
          as part of the action.

     -C
          Modify the curcontext parameter for an action of the form
          '->STATE'.  This is discussed in detail below.

     -R
          Return status 300 instead of zero when a $state is to be
          handled, in the '->STRING' syntax.

     -S
          Do not complete options after a '--' appearing on the line,
          and ignore the '--'.  For example, with -S, in the line

               foobar -x -- -y

          the '-x' is considered an option, the '-y' is considered an
          argument, and the '--' is considered to be neither.

     -A PAT
          Do not complete options after the first non-option argument on
          the line.  PAT is a pattern matching all strings which are not
          to be taken as arguments.  For example, to make _arguments
          stop completing options after the first normal argument, but
          ignoring all strings starting with a hyphen even if they are
          not described by one of the OPTSPECs, the form is '-A "-*"'.

     -O NAME
          Pass the elements of the array NAME as arguments to functions
          called to execute ACTIONs.  This is discussed in detail below.

     -M MATCHSPEC
          Use the match specification MATCHSPEC for completing option
          names and values.  The default MATCHSPEC allows partial word
          completion after '_' and '-', such as completing '-f-b' to
          '-foo-bar'.  The default MATCHSPEC is:
               r:|[_-]=* r:|=*

     -0
          When populating values of the 'opt_args' associative array,
          don't backslash-escape colons and backslashes and use NUL
          rather than colon for joining multiple values.  This option is
          described in more detail below, under the heading _SPECs:
          actions_.

     _SPECs: overview_

     Each of the following forms is a SPEC describing individual sets of
     options or arguments on the command line being analyzed.

     N:MESSAGE:ACTION
     N::MESSAGE:ACTION
          This describes the N'th normal argument.  The MESSAGE will be
          printed above the matches generated and the ACTION indicates
          what can be completed in this position (see below).  If there
          are two colons before the MESSAGE the argument is optional.
          If the MESSAGE contains only white space, nothing will be
          printed above the matches unless the action adds an
          explanation string itself.

     :MESSAGE:ACTION
     ::MESSAGE:ACTION
          Similar, but describes the _next_ argument, whatever number
          that happens to be.  If all arguments are specified in this
          form in the correct order the numbers are unnecessary.

     *:MESSAGE:ACTION
     *::MESSAGE:ACTION
     *:::MESSAGE:ACTION
          This describes how arguments (usually non-option arguments,
          those not beginning with - or +) are to be completed when
          neither of the first two forms was provided.  Any number of
          arguments can be completed in this fashion.

          With two colons before the MESSAGE, the words special array
          and the CURRENT special parameter are modified to refer only
          to the normal arguments when the ACTION is executed or
          evaluated.  With three colons before the MESSAGE they are
          modified to refer only to the normal arguments covered by this
          description.

     OPTSPEC
     OPTSPEC:...
          This describes an option.  The colon indicates handling for
          one or more arguments to the option; if it is not present, the
          option is assumed to take no arguments.

          The following forms are available for the initial OPTSPEC,
          whether or not the option has arguments.

          *OPTSPEC
               Here OPTSPEC is one of the remaining forms below.  This
               indicates the following OPTSPEC may be repeated.
               Otherwise if the corresponding option is already present
               on the command line to the left of the cursor it will not
               be offered again.

          -OPTNAME
          +OPTNAME
               In the simplest form the OPTSPEC is just the option name
               beginning with a minus or a plus sign, such as '-foo'.
               The first argument for the option (if any) must follow as
               a _separate_ word directly after the option.

               Either of '-+OPTNAME' and '+-OPTNAME' can be used to
               specify that -OPTNAME and +OPTNAME are both valid.

               In all the remaining forms, the leading '-' may be
               replaced by or paired with '+' in this way.

          -OPTNAME-
               The first argument of the option must come directly after
               the option name _in the same word_.  For example,
               '-foo-:...' specifies that the completed option and
               argument will look like '-fooARG'.

          -OPTNAME+
               The first argument may appear immediately after OPTNAME
               in the same word, or may appear as a separate word after
               the option.  For example, '-foo+:...' specifies that the
               completed option and argument will look like either
               '-fooARG' or '-foo ARG'.

          -OPTNAME=
               The argument may appear as the next word, or in same word
               as the option name provided that it is separated from it
               by an equals sign, for example '-foo=ARG' or '-foo ARG'.

          -OPTNAME=-
               The argument to the option must appear after an equals
               sign in the same word, and may not be given in the next
               argument.

          OPTSPEC[EXPLANATION]
               An explanation string may be appended to any of the
               preceding forms of OPTSPEC by enclosing it in brackets,
               as in '-q[query operation]'.

               The verbose style is used to decide whether the
               explanation strings are displayed with the option in a
               completion listing.

               If no bracketed explanation string is given but the
               auto-description style is set and only one argument is
               described for this OPTSPEC, the value of the style is
               displayed, with any appearance of the sequence '%d' in it
               replaced by the MESSAGE of the first OPTARG that follows
               the OPTSPEC; see below.

          It is possible for options with a literal '+' or '=' to
          appear, but that character must be quoted, for example '-\+'.

          Each OPTARG following an OPTSPEC must take one of the
          following forms:

          :MESSAGE:ACTION
          ::MESSAGE:ACTION
               An argument to the option; MESSAGE and ACTION are treated
               as for ordinary arguments.  In the first form, the
               argument is mandatory, and in the second form it is
               optional.

               This group may be repeated for options which take
               multiple arguments.  In other words,
               :MESSAGE1:ACTION1:MESSAGE2:ACTION2 specifies that the
               option takes two arguments.

          :*PATTERN:MESSAGE:ACTION
          :*PATTERN::MESSAGE:ACTION
          :*PATTERN:::MESSAGE:ACTION
               This describes multiple arguments.  Only the last OPTARG
               for an option taking multiple arguments may be given in
               this form.  If the PATTERN is empty (i.e.  :*:), all the
               remaining words on the line are to be completed as
               described by the ACTION; otherwise, all the words up to
               and including a word matching the PATTERN are to be
               completed using the ACTION.

               Multiple colons are treated as for the '*:...' forms for
               ordinary arguments: when the MESSAGE is preceded by two
               colons, the words special array and the CURRENT special
               parameter are modified during the execution or evaluation
               of the ACTION to refer only to the words after the
               option.  When preceded by three colons, they are modified
               to refer only to the words covered by this description.

     Any literal colon in an OPTNAME, MESSAGE, or ACTION must be
     preceded by a backslash, '\:'.

     Each of the forms above may be preceded by a list in parentheses of
     option names and argument numbers.  If the given option is on the
     command line, the options and arguments indicated in parentheses
     will not be offered.  For example, '(-two -three 1)-one:...'
     completes the option '-one'; if this appears on the command line,
     the options -two and -three and the first ordinary argument will
     not be completed after it.  '(-foo):...' specifies an ordinary
     argument completion; -foo will not be completed if that argument is
     already present.

     Other items may appear in the list of excluded options to indicate
     various other items that should not be applied when the current
     specification is matched: a single star (*) for the rest arguments
     (i.e.  a specification of the form '*:...'); a colon (:) for all
     normal (non-option-) arguments; and a hyphen (-) for all options.
     For example, if '(*)' appears before an option and the option
     appears on the command line, the list of remaining arguments (those
     shown in the above table beginning with '*:') will not be
     completed.

     To aid in reuse of specifications, it is possible to precede any of
     the forms above with '!'; then the form will no longer be
     completed, although if the option or argument appears on the
     command line they will be skipped as normal.  The main use for this
     is when the arguments are given by an array, and _arguments is
     called repeatedly for more specific contexts: on the first call
     '_arguments $global_options' is used, and on subsequent calls
     '_arguments !$^global_options'.

     _SPECs: actions_

     In each of the forms above the ACTION determines how completions
     should be generated.  Except for the '->STRING' form below, the
     ACTION will be executed by calling the _all_labels function to
     process all tag labels.  No special handling of tags is needed
     unless a function call introduces a new one.

     The functions called to execute ACTIONs will be called with the
     elements of the array named by the '-O NAME' option as arguments.
     This can be used, for example, to pass the same set of options for
     the compadd builtin to all ACTIONs.

     The forms for ACTION are as follows.

      (single unquoted space)
          This is useful where an argument is required but it is not
          possible or desirable to generate matches for it.  The MESSAGE
          will be displayed but no completions listed.  Note that even
          in this case the colon at the end of the MESSAGE is needed; it
          may only be omitted when neither a MESSAGE nor an ACTION is
          given.

     (ITEM1 ITEM2 ...)
          One of a list of possible matches, for example:

               :foo:(foo bar baz)

     ((ITEM1\:DESC1 ...))
          Similar to the above, but with descriptions for each possible
          match.  Note the backslash before the colon.  For example,

               :foo:((a\:bar b\:baz))

          The matches will be listed together with their descriptions if
          the description style is set with the values tag in the
          context.

     ->STRING
          In this form, _arguments processes the arguments and options
          and then returns control to the calling function with
          parameters set to indicate the state of processing; the
          calling function then makes its own arrangements for
          generating completions.  For example, functions that implement
          a state machine can use this type of action.

          Where _arguments encounters ACTION in the '->STRING' format,
          it will strip all leading and trailing whitespace from STRING
          and set the array state to the set of all STRINGs for which an
          action is to be performed.  The elements of the array
          state_descr are assigned the corresponding MESSAGE field from
          each OPTARG containing such an ACTION.

          By default and in common with all other well behaved
          completion functions, _arguments returns status zero if it was
          able to add matches and non-zero otherwise.  However, if the
          -R option is given, _arguments will instead return a status of
          300 to indicate that $state is to be handled.

          In addition to $state and $state_descr, _arguments also sets
          the global parameters 'context', 'line' and 'opt_args' as
          described below, and does not reset any changes made to the
          special parameters such as PREFIX and words.  This gives the
          calling function the choice of resetting these parameters or
          propagating changes in them.

          A function calling _arguments with at least one action
          containing a '->STRING' must therefore declare appropriate
          local parameters:

               local context state state_descr line
               typeset -A opt_args

          to prevent _arguments from altering the global environment.

     {EVAL-STRING}
          A string in braces is evaluated as shell code to generate
          matches.  If the EVAL-STRING itself does not begin with an
          opening parenthesis or brace it is split into separate words
          before execution.

     = ACTION
          If the ACTION starts with '= ' (an equals sign followed by a
          space), _arguments will insert the contents of the ARGUMENT
          field of the current context as the new first element in the
          words special array and increment the value of the CURRENT
          special parameter.  This has the effect of inserting a dummy
          word onto the completion command line while not changing the
          point at which completion is taking place.

          This is most useful with one of the specifiers that restrict
          the words on the command line on which the ACTION is to
          operate (the two- and three-colon forms above).  One
          particular use is when an ACTION itself causes _arguments on a
          restricted range; it is necessary to use this trick to insert
          an appropriate command name into the range for the second call
          to _arguments to be able to parse the line.

      WORD...
     WORD...
          This covers all forms other than those above.  If the ACTION
          starts with a space, the remaining list of words will be
          invoked unchanged.

          Otherwise it will be invoked with some extra strings placed
          after the first word; these are to be passed down as options
          to the compadd builtin.  They ensure that the state specified
          by _arguments, in particular the descriptions of options and
          arguments, is correctly passed to the completion command.
          These additional arguments are taken from the array parameter
          'expl'; this will be set up before executing the ACTION and
          hence may be referred to inside it, typically in an expansion
          of the form '$expl[@]' which preserves empty elements of the
          array.

     During the performance of the action the array 'line' will be set
     to the normal arguments from the command line, i.e.  the words from
     the command line after the command name excluding all options and
     their arguments.  Options are stored in the associative array
     'opt_args' with option names as keys and their arguments as the
     values.  By default, all colons and backslashes in the value are
     escaped with backslashes, and if an option has multiple arguments
     (for example, when using an OPTSPEC of the form '*OPTSPEC'), they
     are joined with (unescaped) colons.  However, if the -0 option was
     passed, no backslash escaping is performed, and multiple values are
     joined with NUL bytes.  For example, after 'zsh -o foo:foo -o
     bar:bar -o <TAB>', the contents of 'opt_args' would be

          typeset -A opt_args=( [-o]='foo\:foo:bar\:bar:' )

     by default, and

          typeset -A opt_args=( [-o]=$'foo:foo\x00bar:bar\x00' )

     if _arguments had been called with the -0 option.

     The parameter 'context' is set when returning to the calling
     function to perform an action of the form '->STRING'.  It is set to
     an array of elements corresponding to the elements of $state.  Each
     element is a suitable name for the argument field of the context:
     either a string of the form 'option-OPT-N' for the N'th argument of
     the option -OPT, or a string of the form 'argument-N' for the N'th
     argument.  For 'rest' arguments, that is those in the list at the
     end not handled by position, N is the string 'rest'.  For example,
     when completing the argument of the -o option, the name is
     'option-o-1', while for the second normal (non-option-) argument it
     is 'argument-2'.

     Furthermore, during the evaluation of the ACTION the context name
     in the curcontext parameter is altered to append the same string
     that is stored in the context parameter.

     The option -C tells _arguments to modify the curcontext parameter
     for an action of the form '->STATE'.  This is the standard
     parameter used to keep track of the current context.  Here it (and
     not the context array) should be made local to the calling function
     to avoid passing back the modified value and should be initialised
     to the current value at the start of the function:

          local curcontext="$curcontext"

     This is useful where it is not possible for multiple states to be
     valid together.

     _Grouping Options_

     Options can be grouped to simplify exclusion lists.  A group is
     introduced with '+' followed by a name for the group in the
     subsequent word.  Whole groups can then be referenced in an
     exclusion list or a group name can be used to disambiguate between
     two forms of the same option.  For example:

          _arguments \
              '(group2--x)-a' \
            + group1 \
              -m \
              '(group2)-n' \
            + group2 \
              -x -y

     If the name of a group is specified in the form '(NAME)' then only
     one value from that group will ever be completed; more formally,
     all specifications are mutually exclusive to all other
     specifications in that group.  This is useful for defining options
     that are aliases for each other.  For example:

          _arguments \
              -a -b \
            + '(operation)' \
              {-c,--compress}'[compress]' \
              {-d,--decompress}'[decompress]' \
              {-l,--list}'[list]'

     If an option in a group appears on the command line, it is stored
     in the associative array 'opt_args' with 'GROUP-OPTION' as a key.
     In the example above, a key 'operation--c' is used if the option
     '-c' is present on the command line.

     _Specifying Multiple Sets of Arguments_

     It is possible to specify multiple sets of options and arguments
     with the sets separated by single hyphens.  This differs from
     groups in that sets are considered to be mutually exclusive of each
     other.

     Specifications before the first set and from any group are common
     to all sets.  For example:

          _arguments \
              -a \
            - set1 \
              -c \
            - set2 \
              -d \
              ':arg:(x2 y2)'

     This defines two sets.  When the command line contains the option
     '-c', the '-d' option and the argument will not be considered
     possible completions.  When it contains '-d' or an argument, the
     option '-c' will not be considered.  However, after '-a' both sets
     will still be considered valid.

     As for groups, the name of a set may appear in exclusion lists,
     either alone or preceding a normal option or argument
     specification.

     The completion code has to parse the command line separately for
     each set.  This can be slow so sets should only be used when
     necessary.  A useful alternative is often an option specification
     with rest-arguments (as in '-foo:*:...'); here the option -foo
     swallows up all remaining arguments as described by the OPTARG
     definitions.

     _Deriving SPEC forms from the help output_

     The option '--' allows _arguments to work out the names of long
     options that support the '--help' option which is standard in many
     GNU commands.  The command word is called with the argument
     '--help' and the output examined for option names.  Clearly, it can
     be dangerous to pass this to commands which may not support this
     option as the behaviour of the command is unspecified.

     In addition to options, '_arguments --' will try to deduce the
     types of arguments available for options when the form '--OPT=VAL'
     is valid.  It is also possible to provide hints by examining the
     help text of the command and adding HELPSPEC of the form
     'PATTERN:MESSAGE:ACTION'; note that other _arguments SPEC forms are
     not used.  The PATTERN is matched against the help text for an
     option, and if it matches the MESSAGE and ACTION are used as for
     other argument specifiers.  The special case of '*:' means both
     MESSAGE and ACTION are empty, which has the effect of causing
     options having no description in the help output to be ordered in
     listings ahead of options that have a description.

     For example:

          _arguments -- '*\*:toggle:(yes no)' \
                        '*=FILE*:file:_files' \
                        '*=DIR*:directory:_files -/' \
                        '*=PATH*:directory:_files -/'

     Here, 'yes' and 'no' will be completed as the argument of options
     whose description ends in a star; file names will be completed for
     options that contain the substring '=FILE' in the description; and
     directories will be completed for options whose description
     contains '=DIR' or '=PATH'.  The last three are in fact the default
     and so need not be given explicitly, although it is possible to
     override the use of these patterns.  A typical help text which uses
     this feature is:

            -C, --directory=DIR          change to directory DIR

     so that the above specifications will cause directories to be
     completed after '--directory', though not after '-C'.

     Note also that _arguments tries to find out automatically if the
     argument for an option is optional.  This can be specified
     explicitly by doubling the colon before the MESSAGE.

     If the PATTERN ends in '(-)', this will be removed from the pattern
     and the ACTION will be used only directly after the '=', not in the
     next word.  This is the behaviour of a normal specification defined
     with the form '=-'.

     By default, the command (with the option '--help') is run after
     resetting all the locale categories (except for LC_CTYPE) to 'C'.
     If the localized help output is known to work, the option '-l' can
     be specified after the '_arguments --' so that the command is run
     in the current locale.

     The '_arguments --' can be followed by the option '-i PATTERNS' to
     give patterns for options which are not to be completed.  The
     patterns can be given as the name of an array parameter or as a
     literal list in parentheses.  For example,

          _arguments -- -i \
              "(--(en|dis)able-FEATURE*)"

     will cause completion to ignore the options '--enable-FEATURE' and
     '--disable-FEATURE' (this example is useful with GNU configure).

     The '_arguments --' form can also be followed by the option '-s
     PAIR' to describe option aliases.  The PAIR consists of a list of
     alternating patterns and corresponding replacements, enclosed in
     parens and quoted so that it forms a single argument word in the
     _arguments call.

     For example, some configure-script help output describes options
     only as '--enable-foo', but the script also accepts the negated
     form '--disable-foo'.  To allow completion of the second form:

          _arguments -- -s "((#s)--enable- --disable-)"

     _Miscellaneous notes_

     Finally, note that _arguments generally expects to be the primary
     function handling any completion for which it is used.  It may have
     side effects which change the treatment of any matches added by
     other functions called after it.  To combine _arguments with other
     functions, those functions should be called either before
     _arguments, as an ACTION within a SPEC, or in handlers for
     '->STATE' actions.

     Here is a more general example of the use of _arguments:

          _arguments '-l+:left border:' \
                     '-format:paper size:(letter A4)' \
                     '*-copy:output file:_files::resolution:(300 600)' \
                     ':postscript file:_files -g \*.\(ps\|eps\)' \
                     '*:page number:'

     This describes three options: '-l', '-format', and '-copy'.  The
     first takes one argument described as 'LEFT BORDER' for which no
     completion will be offered because of the empty action.  Its
     argument may come directly after the '-l' or it may be given as the
     next word on the line.

     The '-format' option takes one argument in the next word, described
     as 'PAPER SIZE' for which only the strings 'letter' and 'A4' will
     be completed.

     The '-copy' option may appear more than once on the command line
     and takes two arguments.  The first is mandatory and will be
     completed as a filename.  The second is optional (because of the
     second colon before the description 'RESOLUTION') and will be
     completed from the strings '300' and '600'.

     The last two descriptions say what should be completed as
     arguments.  The first describes the first argument as a 'POSTSCRIPT
     FILE' and makes files ending in 'ps' or 'eps' be completed.  The
     last description gives all other arguments the description 'PAGE
     NUMBER' but does not offer completions.

_as_if COMMAND [ARG ... ]
     This function is useful when one command should be completed as if
     it were another command with particular arguments.  For example to
     complete foo as if it were bar --baz, use

          compdef '_as_if bar --baz' foo

_cache_invalid CACHE_IDENTIFIER
     This function returns status zero if the completions cache
     corresponding to the given cache identifier needs rebuilding.  It
     determines this by looking up the cache-policy style for the
     current context.  This should provide a function name which is run
     with the full path to the relevant cache file as the only argument.

     Example:

          _example_caching_policy () {
              # rebuild if cache is more than a week old
              local -a oldp
              oldp=( "$1"(Nm+7) )
              (( $#oldp ))
          }

_call_function RETURN NAME [ ARG ... ]
     If a function NAME exists, it is called with the arguments ARGs.
     The RETURN argument gives the name of a parameter in which the
     return status from the function NAME should be stored; if RETURN is
     empty or a single hyphen it is ignored.

     The return status of _call_function itself is zero if the function
     NAME exists and was called and non-zero otherwise.

_call_program [ -l ] [ -p ] TAG STRING ...
     This function provides a mechanism for the user to override the use
     of an external command.  It looks up the command style with the
     supplied TAG.  If the style is set, its value is used as the
     command to execute.  The STRINGs from the call to _call_program, or
     from the style if set, are concatenated with spaces between them
     and the resulting string is evaluated.  The return status is the
     return status of the command called.

     By default, the command is run in an environment where all the
     locale categories (except for LC_CTYPE) are reset to 'C' by calling
     the utility function _comp_locale (see below).  If the option '-l'
     is given, the command is run with the current locale.

     If the option '-p' is supplied it indicates that the command output
     is influenced by the permissions it is run with.  If the
     gain-privileges style is set to true, _call_program will make use
     of commands such as sudo, if present on the command-line, to match
     the permissions to whatever the final command is likely to run
     under.  When looking up the gain-privileges and command styles, the
     command component of the zstyle context will end with a slash ('/')
     followed by the command that would be used to gain privileges.

_combination [ -s PATTERN ] TAG STYLE SPEC ... FIELD OPTS ...
     This function is used to complete combinations of values, for
     example pairs of hostnames and usernames.  The STYLE argument gives
     the style which defines the pairs; it is looked up in a context
     with the TAG specified.

     The style name consists of field names separated by hyphens, for
     example 'users-hosts-ports'.  For each field for a value is already
     known, a SPEC of the form 'FIELD=PATTERN' is given.  For example,
     if the command line so far specifies a user 'pws', the argument
     'users=pws' should appear.

     The next argument with no equals sign is taken as the name of the
     field for which completions should be generated (presumably not one
     of the FIELDs for which the value is known).

     The matches generated will be taken from the value of the style.
     These should contain the possible values for the combinations in
     the appropriate order (users, hosts, ports in the example above).
     The values for the different fields are separated by colons.  This
     can be altered with the option -s to _combination which specifies a
     pattern.  Typically this is a character class, as for example '-s
     "[:@]"' in the case of the users-hosts style.  Each 'FIELD=PATTERN'
     specification restricts the completions which apply to elements of
     the style with appropriately matching fields.

     If no style with the given name is defined for the given tag, or if
     none of the strings in style's value match, but a function name of
     the required field preceded by an underscore is defined, that
     function will be called to generate the matches.  For example, if
     there is no 'users-hosts-ports' or no matching hostname when a host
     is required, the function '_hosts' will automatically be called.

     If the same name is used for more than one field, in both the
     'FIELD=PATTERN' and the argument that gives the name of the field
     to be completed, the number of the field (starting with one) may be
     given after the fieldname, separated from it by a colon.

     All arguments after the required field name are passed to compadd
     when generating matches from the style value, or to the functions
     for the fields if they are called.

_command_names [ -e | - ]
     This function completes words that are valid at command position:
     names of aliases, builtins, hashed commands, functions, and so on.
     With the -e flag, only hashed commands are completed.  The - flag
     is ignored.

_comp_locale
     This function resets all the locale categories other than LC_CTYPE
     to 'C' so that the output from external commands can be easily
     analyzed by the completion system.  LC_CTYPE retains the current
     value (taking LC_ALL and LANG into account), ensuring that
     non-ASCII characters in file names are still handled properly.

     This function should normally be run only in a subshell, because
     the new locale is exported to the environment.  Typical usage would
     be '$(_comp_locale; COMMAND ...)'.

_completers [ -p ]
     This function completes names of completers.

     -p
          Include the leading underscore ('_') in the matches.

_default
     This function corresponds to the -default- special context which is
     applied where no completion is defined.  It is useful to call it
     under certain error conditions such as completion after an
     unrecognised subcommand.  This applies the concept of graceful
     degradation to the completion system, allowing it to fallback on
     basic completion of commonly useful things like filenames.

_describe [-12JVx] [ -oO | -t TAG ] DESCR NAME1 [ NAME2 ] [ OPT ... ]
          [ -- NAME1 [ NAME2 ] [ OPT ... ] ... ]
     This function associates completions with descriptions.  Multiple
     groups separated by -- can be supplied, potentially with different
     completion options OPTs.

     The DESCR is taken as a string to display above the matches if the
     format style for the descriptions tag is set.

     This is followed by one or two names of arrays.  Alternatively, the
     arrays may be given inline, following the rules described below,
     using the syntax (ITEM ...).  (There is no separate ((...)) form as
     with _arguments.)

     The array NAME1 contains the possible completions with their
     (optional) descriptions in the form 'COMPLETION:DESCRIPTION'.  Any
     literal colons in COMPLETION must be quoted with a backslash.  If a
     NAME2 is given, it should have the same number of elements as
     NAME1; in this case the corresponding elements are added as
     possible completions instead of the COMPLETION strings from NAME1.
     The completion list will retain the descriptions from NAME1.

     Finally, a set of options to pass to compadd can appear.

     If the option '-o' appears before the first argument, the matches
     added will be treated as names of command options (N.B. not shell
     options), typically following a '-', '--' or '+' on the command
     line.  In this case _describe uses the prefix-hidden, prefix-needed
     and verbose styles to find out if the strings should be added as
     completions and if the descriptions should be shown.  Without the
     '-o' option, only the verbose style is used to decide how
     descriptions are shown.  If '-O' is used instead of '-o', command
     options are completed as above but _describe will not handle the
     prefix-needed style.

     With the -t option a TAG can be specified.  The default is 'values'
     or, if the -o option is given, 'options'.

     The options -1, -2, -J, -V, -x are passed to _next_label.

     If selected by the list-grouped style, strings with the same
     description will appear together in the list.

     _describe uses the _all_labels function to generate the matches, so
     it does not need to appear inside a loop over tag labels.

_description [ -x ] [ -12VJ ] TAG NAME DESCR [ SPEC ... ]
     This function is not to be confused with the previous one; it is
     used as a helper function for creating options to compadd.  It is
     buried inside many of the higher level completion functions and so
     often does not need to be called directly.

     The styles listed below are tested in the current context using the
     given TAG.  The resulting options for compadd are put into the
     array named NAME (this is traditionally 'expl', but this convention
     is not enforced).  The description for the corresponding set of
     matches is passed to the function in DESCR.

     The styles tested are: format, hidden, matcher, ignore-line,
     ignored-patterns, group-name and sort.  The format style is first
     tested for the given TAG and then for the descriptions tag if no
     value was found, while the remainder are only tested for the tag
     given as the first argument.  The function also calls _setup which
     tests some more styles.

     The string returned by the format style (if any) will be modified
     so that the sequence '%d' is replaced by the DESCR given as the
     third argument without any leading or trailing white space.  If,
     after removing the white space, the DESCR is the empty string, the
     format style will not be used and the options put into the NAME
     array will not contain an explanation string to be displayed above
     the matches.

     If _description is called with more than three arguments, the
     additional SPECs should be of the form 'CHAR:STR'.  These supply
     escape sequence replacements for the format style: every appearance
     of '%CHAR' will be replaced by STRING.  If no additional SPECs are
     given but the description in DESCR conforms to a common form then
     further escape sequences are set for elements of that description.
     These elements correspond to a default value ('%o'), the units
     ('%m') range of acceptable values ('%r') and the remaining initial
     part of the description ('%h').  The form the description takes
     consists of specifying the units and range in parentheses and the
     default value in square brackets, for example:

          _description times expl 'timeout (seconds) (0-60) [20]'

     It is possible to use zformat conditional expressions when styling
     these elements.  So, for example, to add 'default:' as a tag but
     only when there is a default value to show, the format style might
     include '%(o.default: %o.)'.

     If the -x option is given, the description will be passed to
     compadd using the -x option instead of the default -X.  This means
     that the description will be displayed even if there are no
     corresponding matches.

     The options placed in the array NAME take account of the group-name
     style, so matches are placed in a separate group where necessary.
     The group normally has its elements sorted (by passing the option
     -J to compadd), but if an option starting with '-V', '-J', '-1', or
     '-2' is passed to _description, that option will be included in the
     array.  Hence it is possible for the completion group to be
     unsorted by giving the option '-V', '-1V', or '-2V'.

     In most cases, the function will be used like this:

          local expl
          _description files expl file
          compadd "$expl[@]" - "$files[@]"

     Note the use of the parameter expl, the hyphen, and the list of
     matches.  Almost all calls to compadd within the completion system
     use a similar format; this ensures that user-specified styles are
     correctly passed down to the builtins which implement the internals
     of completion.

_dir_list [ -s SEP ] [ -S ]
     Complete a list of directory names separated by colons (the same
     format as $PATH).

     -s SEP
          Use SEP as separator between items.  SEP defaults to a colon
          (':').

     -S
          Add SEP instead of slash ('/') as an autoremoveable suffix.

_dispatch CONTEXT STRING ...
     This sets the current context to CONTEXT and looks for completion
     functions to handle this context by hunting through the list of
     command names or special contexts (as described above for compdef)
     given as STRINGs.  The first completion function to be defined for
     one of the contexts in the list is used to generate matches.
     Typically, the last STRING is -default- to cause the function for
     default completion to be used as a fallback.

     The function sets the parameter $service to the STRING being tried,
     and sets the CONTEXT/COMMAND field (the fourth) of the $curcontext
     parameter to the CONTEXT given as the first argument.

_email_addresses [ -c ] [ -n PLUGIN ]
     Complete email addresses.  Addresses are provided by plugins.

     -c
          Complete bare localhost@domain.tld addresses, without a name
          part or a comment.  Without this option, RFC822 'FIRSTNAME
          LASTNAME <ADDRESS>' strings are completed.

     -n PLUGIN
          Complete aliases from PLUGIN.

     The following plugins are available by default: _email-ldap (see
     the filter style), _email-local (completes USER@HOSTNAME Unix
     addresses), _email-mail (completes aliases from ~/.mailrc),
     _email-mush, _email-mutt, and _email-pine.

     Addresses from the _email-FOO plugin are added under the tag
     'email-FOO'.

     _Writing plugins_

     Plugins are written as separate functions with names starting with
     '_email-'.  They are invoked with the -c option and compadd
     options.  They should either do their own completion or set the
     $reply array to a list of 'ALIAS:ADDRESS' elements and return 300.
     New plugins will be picked up and run automatically.

_files
     The function _files is a wrapper around _path_files.  It supports
     all of the same functionality, with some enhancements -- notably,
     it respects the list-dirs-first style, and it allows users to
     override the behaviour of the -g and -/ options with the
     file-patterns style.  _files should therefore be preferred over
     _path_files in most cases.

     This function accepts the full set of options allowed by
     _path_files, described below.

_gnu_generic
     This function is a simple wrapper around the _arguments function
     described above.  It can be used to determine automatically the
     long options understood by commands that produce a list when passed
     the option '--help'.  It is intended to be used as a top-level
     completion function in its own right.  For example, to enable
     option completion for the commands foo and bar, use

          compdef _gnu_generic foo bar

     after the call to compinit.

     The completion system as supplied is conservative in its use of
     this function, since it is important to be sure the command
     understands the option '--help'.

_guard [ OPTIONS ] PATTERN DESCR
     This function displays DESCR if PATTERN matches the string to be
     completed.  It is intended to be used in the ACTION for the
     specifications passed to _arguments and similar functions.

     The return status is zero if the message was displayed and the word
     to complete is not empty, and non-zero otherwise.

     The PATTERN may be preceded by any of the options understood by
     compadd that are passed down from _description, namely -M, -J, -V,
     -1, -2, -n, -F and -X.  All of these options will be ignored.  This
     fits in conveniently with the argument-passing conventions of
     actions for _arguments.

     As an example, consider a command taking the options -n and -none,
     where -n must be followed by a numeric value in the same word.  By
     using:

          _arguments '-n-: :_guard "[0-9]#" "numeric value"' '-none'

     _arguments can be made to both display the message 'numeric value'
     and complete options after '-n<TAB>'.  If the '-n' is already
     followed by one or more digits (the pattern passed to _guard) only
     the message will be displayed; if the '-n' is followed by another
     character, only options are completed.

_message [ -r12 ] [ -VJ GROUP ] DESCR
_message -e [ TAG ] DESCR
     The DESCR is used in the same way as the third argument to the
     _description function, except that the resulting string will always
     be shown whether or not matches were generated.  This is useful for
     displaying a help message in places where no completions can be
     generated.

     The format style is examined with the messages tag to find a
     message; the usual tag, descriptions, is used only if the style is
     not set with the former.

     If the -r option is given, no style is used; the DESCR is taken
     literally as the string to display.  This is most useful when the
     DESCR comes from a pre-processed argument list which already
     contains an expanded description.  Note that this option does not
     disable the '%'-sequence parsing done by compadd.

     The -12VJ options and the GROUP are passed to compadd and hence
     determine the group the message string is added to.

     The second -e form gives a description for completions with the tag
     TAG to be shown even if there are no matches for that tag.  This
     form is called by _arguments in the event that there is no action
     for an option specification.  The tag can be omitted and if so the
     tag is taken from the parameter $curtag; this is maintained by the
     completion system and so is usually correct.  Note that if there
     are no matches at the time this function is called,
     compstate[insert] is cleared, so additional matches generated later
     are not inserted on the command line.

_multi_parts [ -i ] SEP ARRAY
     The argument SEP is a separator character.  The ARRAY may be either
     the name of an array parameter or a literal array in the form '(foo
     bar)', a parenthesised list of words separated by whitespace.  The
     possible completions are the strings from the array.  However, each
     chunk delimited by SEP will be completed separately.  For example,
     the _tar function uses '_multi_parts / PATHARRAY' to complete
     partial file paths from the given array of complete file paths.

     The -i option causes _multi_parts to insert a unique match even if
     that requires multiple separators to be inserted.  This is not
     usually the expected behaviour with filenames, but certain other
     types of completion, for example those with a fixed set of
     possibilities, may be more suited to this form.

     Like other utility functions, this function accepts the '-V', '-J',
     '-1', '-2', '-n', '-f', '-X', '-M', '-P', '-S', '-r', '-R', and
     '-q' options and passes them to the compadd builtin.

_next_label [ -x ] [ -12VJ ] TAG NAME DESCR [ OPTION ... ]
     This function is used to implement the loop over different tag
     labels for a particular tag as described above for the tag-order
     style.  On each call it checks to see if there are any more tag
     labels; if there is it returns status zero, otherwise non-zero.  As
     this function requires a current tag to be set, it must always
     follow a call to _tags or _requested.

     The -x12VJ options and the first three arguments are passed to the
     _description function.  Where appropriate the TAG will be replaced
     by a tag label in this call.  Any description given in the
     tag-order style is preferred to the DESCR passed to _next_label.

     The OPTIONs given after the DESCR are set in the parameter given by
     NAME, and hence are to be passed to compadd or whatever function is
     called to add the matches.

     Here is a typical use of this function for the tag foo.  The call
     to _requested determines if tag foo is required at all; the loop
     over _next_label handles any labels defined for the tag in the
     tag-order style.

          local expl ret=1
          ...
          if _requested foo; then
            ...
            while _next_label foo expl '...'; do
              compadd "$expl[@]" ... && ret=0
            done
            ...
          fi
          return ret

_normal [ -P | -p PRECOMMAND ]
     This is the standard function called to handle completion outside
     any special -CONTEXT-.  It is called both to complete the command
     word and also the arguments for a command.  In the second case,
     _normal looks for a special completion for that command, and if
     there is none it uses the completion for the -default- context.

     A second use is to reexamine the command line specified by the
     $words array and the $CURRENT parameter after those have been
     modified.  For example, the function _precommand, which completes
     after precommand specifiers such as nohup, removes the first word
     from the words array, decrements the CURRENT parameter, then calls
     '_normal -p $service'.  The effect is that 'nohup CMD ...' is
     treated in the same way as 'CMD ...'.

     -P
          Reset the list of precommands.  This option should be used if
          completing a command line which allows internal commands (e.g.
          builtins and functions) regardless of prior precommands (e.g.
          'zsh -c').

     -p PRECOMMAND
          Append PRECOMMAND to the list of precommands.  This option
          should be used in nearly all cases in which -P is not
          applicable.

     If the command name matches one of the patterns given by one of the
     options -p or -P to compdef, the corresponding completion function
     is called and then the parameter _compskip is checked.  If it is
     set completion is terminated at that point even if no matches have
     been found.  This is the same effect as in the -first- context.

_numbers [ OPTION ... ] [ DESCRIPTION ] [ SUFFIX ... ]
     This can be used where a number is followed by a suffix to indicate
     the units.  The unit suffixes are completed and can also be
     included in the description used when completion is invoked for the
     preceding number.

     In addition to common compadd options, _numbers accepts the
     following options:

     -t TAG
          Specify a tag to use instead of the default of numbers.

     -u UNITS
          Indicate the default units for the number, e.g.  bytes.

     -l MIN
          Specify the lowest possible value for the number.

     -m MAX
          Specify the highest possible value for the number.

     -d DEFAULT
          Specify the default value.

     -N
          Allow negative numbers.  This is implied if the range includes
          a negative.

     -f
          Allow decimal numbers.

     Where a particular suffix represents the default units for a
     number, it should be prefixed with a colon.  Additionally, suffixes
     can be followed by a colon and a description.  So for example, the
     following allows the age of something to be specified, either in
     seconds or with an optional suffix with a longer unit of time:

          _numbers -u seconds age :s:seconds m:minutes h:hours d:days

     It is typically helpful for units to be presented in order of
     magnitude when completed.  To facilitate this, the order in which
     they are given is preserved.

     When the format style is looked up with the descriptions tag or the
     tag specified with -t, the list of suffixes is available as a '%x'
     escape sequence.  This is in addition to the usual sequences
     documented under the format style.  The form this list takes can
     also be configured.  To this end, the format style is first looked
     up with the tag unit-suffixes.  The retrieved format is applied to
     each suffix in turn and the results are then concatenated to form
     the completed list.  For the unit-suffixes format, '%x' expands to
     the individual suffix and '%X' to its description.  %d' indicates a
     default suffix and can be used in a condition.  The index and
     reverse index are set in '%i' and '%r' respectively and are useful
     for text included only with the first and last suffixes in the
     list.  So for example, the following joins the suffixes together as
     a comma-separated list:

          zstyle ':completion:*:unit-suffixes' format '%x%(r::,)'

_options
     This can be used to complete the names of shell options.  It
     provides a matcher specification that ignores a leading 'no',
     ignores underscores and allows upper-case letters to match their
     lower-case counterparts (for example, 'glob', 'noglob', 'NO_GLOB'
     are all completed).  Any arguments are propagated to the compadd
     builtin.

_options_set and _options_unset
     These functions complete only set or unset options, with the same
     matching specification used in the _options function.

     Note that you need to uncomment a few lines in the _main_complete
     function for these functions to work properly.  The lines in
     question are used to store the option settings in effect before the
     completion widget locally sets the options it needs.  Hence these
     functions are not generally used by the completion system.

_parameters
     This is used to complete the names of shell parameters.

     The option '-g PATTERN' limits the completion to parameters whose
     type matches the PATTERN.  The type of a parameter is that shown by
     'print ${(t)PARAM}', hence judicious use of '*' in PATTERN is
     probably necessary.

     All other arguments are passed to the compadd builtin.

_path_files
     This function is used throughout the completion system to complete
     filenames.  It allows completion of partial paths.  For example,
     the string '/u/i/s/sig' may be completed to
     '/usr/include/sys/signal.h'.

     The options accepted by both _path_files and _files are:

     -f
          Complete all filenames.  This is the default.

     -/
          Specifies that only directories should be completed.

     -g PATTERN
          Specifies that only files matching the PATTERN should be
          completed.

     -W PATHS
          Specifies path prefixes that are to be prepended to the string
          from the command line to generate the filenames but that
          should not be inserted as completions nor shown in completion
          listings.  Here, PATHS may be the name of an array parameter,
          a literal list of paths enclosed in parentheses or an absolute
          pathname.

     -F IGNORED-FILES
          This behaves as for the corresponding option to the compadd
          builtin.  It gives direct control over which filenames should
          be ignored.  If the option is not present, the
          ignored-patterns style is used.

     Both _path_files and _files also accept the following options which
     are passed to compadd: '-J', '-V', '-1', '-2', '-n', '-X', '-M',
     '-P', '-S', '-q', '-r', and '-R'.

     Finally, the _path_files function uses the styles expand,
     ambiguous, special-dirs, list-suffixes and file-sort described
     above.

_pick_variant [ -b BUILTIN-LABEL ] [ -c COMMAND ] [ -r NAME ]
              LABEL=PATTERN ... LABEL [ ARG ... ]
     This function is used to resolve situations where a single command
     name requires more than one type of handling, either because it has
     more than one variant or because there is a name clash between two
     different commands.

     The command to run is taken from the first element of the array
     words unless this is overridden by the option -c.  This command is
     run and its output is compared with a series of patterns.
     Arguments to be passed to the command can be specified at the end
     after all the other arguments.  The patterns to try in order are
     given by the arguments LABEL=PATTERN; if the output of 'COMMAND ARG
     ...'  contains PATTERN, then LABEL is selected as the label for the
     command variant.  If none of the patterns match, the final command
     label is selected and status 1 is returned.

     If the '-b BUILTIN-LABEL' is given, the command is tested to see if
     it is provided as a shell builtin, possibly autoloaded; if so, the
     label BUILTIN-LABEL is selected as the label for the variant.

     If the '-r NAME' is given, the LABEL picked is stored in the
     parameter named NAME.

     The results are also cached in the _cmd_variant associative array
     indexed by the name of the command run.

_regex_arguments NAME SPEC ...
     This function generates a completion function NAME which matches
     the specifications SPECs, a set of regular expressions as described
     below.  After running _regex_arguments, the function NAME should be
     called as a normal completion function.  The pattern to be matched
     is given by the contents of the words array up to the current
     cursor position joined together with null characters; no quotation
     is applied.

     The arguments are grouped as sets of alternatives separated by '|',
     which are tried one after the other until one matches.  Each
     alternative consists of a one or more specifications which are
     tried left to right, with each pattern matched being stripped in
     turn from the command line being tested, until all of the group
     succeeds or until one fails; in the latter case, the next
     alternative is tried.  This structure can be repeated to arbitrary
     depth by using parentheses; matching proceeds from inside to
     outside.

     A special procedure is applied if no test succeeds but the
     remaining command line string contains no null character (implying
     the remaining word is the one for which completions are to be
     generated).  The completion target is restricted to the remaining
     word and any ACTIONs for the corresponding patterns are executed.
     In this case, nothing is stripped from the command line string.
     The order of evaluation of the ACTIONs can be determined by the
     tag-order style; the various formats supported by _alternative can
     be used in ACTION.  The DESCR is used for setting up the array
     parameter expl.

     Specification arguments take one of following forms, in which
     metacharacters such as '(', ')', '#' and '|' should be quoted.

     /PATTERN/ [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is a single primitive component.  The function tests
          whether the combined pattern '(#b)((#B)PATTERN)LOOKAHEAD*'
          matches the command line string.  If so, 'GUARD' is evaluated
          and its return status is examined to determine if the test has
          succeeded.  The PATTERN string '[]' is guaranteed never to
          match.  The LOOKAHEAD is not stripped from the command line
          before the next pattern is examined.

          The argument starting with : is used in the same manner as an
          argument to _alternative.

          A component is used as follows: PATTERN is tested to see if
          the component already exists on the command line.  If it does,
          any following specifications are examined to find something to
          complete.  If a component is reached but no such pattern
          exists yet on the command line, the string containing the
          ACTION is used to generate matches to insert at that point.

     /PATTERN/+ [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is similar to '/PATTERN/ ...'  but the left part of the
          command line string (i.e.  the part already matched by
          previous patterns) is also considered part of the completion
          target.

     /PATTERN/- [%LOOKAHEAD%] [-GUARD] [:TAG:DESCR:ACTION]
          This is similar to '/PATTERN/ ...'  but the ACTIONs of the
          current and previously matched patterns are ignored even if
          the following 'PATTERN' matches the empty string.

     ( SPEC )
          Parentheses may be used to groups SPECs; note each parenthesis
          is a single argument to _regex_arguments.

     SPEC #
          This allows any number of repetitions of SPEC.

     SPEC SPEC
          The two SPECs are to be matched one after the other as
          described above.

     SPEC | SPEC
          Either of the two SPECs can be matched.

     The function _regex_words can be used as a helper function to
     generate matches for a set of alternative words possibly with their
     own arguments as a command line argument.

     Examples:

          _regex_arguments _tst /$'[^\0]#\0'/ \
              /$'[^\0]#\0'/ :'compadd aaa'

     This generates a function _tst that completes aaa as its only
     argument.  The TAG and DESCRIPTION for the action have been omitted
     for brevity (this works but is not recommended in normal use).  The
     first component matches the command word, which is arbitrary; the
     second matches any argument.  As the argument is also arbitrary,
     any following component would not depend on aaa being present.

          _regex_arguments _tst /$'[^\0]#\0'/ \
              /$'aaa\0'/ :'compadd aaa'

     This is a more typical use; it is similar, but any following
     patterns would only match if aaa was present as the first argument.

          _regex_arguments _tst /$'[^\0]#\0'/ \( \
              /$'aaa\0'/ :'compadd aaa' \
              /$'bbb\0'/ :'compadd bbb' \) \#

     In this example, an indefinite number of command arguments may be
     completed.  Odd arguments are completed as aaa and even arguments
     as bbb.  Completion fails unless the set of aaa and bbb arguments
     before the current one is matched correctly.

          _regex_arguments _tst /$'[^\0]#\0'/ \
              \( /$'aaa\0'/ :'compadd aaa' \| \
              /$'bbb\0'/ :'compadd bbb' \) \#

     This is similar, but either aaa or bbb may be completed for any
     argument.  In this case _regex_words could be used to generate a
     suitable expression for the arguments.

_regex_words TAG DESCRIPTION SPEC ...
     This function can be used to generate arguments for the
     _regex_arguments command which may be inserted at any point where a
     set of rules is expected.  The TAG and DESCRIPTION give a standard
     tag and description pertaining to the current context.  Each SPEC
     contains two or three arguments separated by a colon: note that
     there is no leading colon in this case.

     Each SPEC gives one of a set of words that may be completed at this
     point, together with arguments.  It is thus roughly equivalent to
     the _arguments function when used in normal (non-regex) completion.

     The part of the SPEC before the first colon is the word to be
     completed.  This may contain a *; the entire word, before and after
     the * is completed, but only the text before the * is required for
     the context to be matched, so that further arguments may be
     completed after the abbreviated form.

     The second part of SPEC is a description for the word being
     completed.

     The optional third part of the SPEC describes how words following
     the one being completed are themselves to be completed.  It will be
     evaluated in order to avoid problems with quoting.  This means that
     typically it contains a reference to an array containing previously
     generated regex arguments.

     The option -t TERM specifies a terminator for the word instead of
     the usual space.  This is handled as an auto-removable suffix in
     the manner of the option -s SEP to _values.

     The result of the processing by _regex_words is placed in the array
     reply, which should be made local to the calling function.  If the
     set of words and arguments may be matched repeatedly, a # should be
     appended to the generated array at that point.

     For example:

          local -a reply
          _regex_words mydb-commands 'mydb commands' \
            'add:add an entry to mydb:$mydb_add_cmds' \
            'show:show entries in mydb'
          _regex_arguments _mydb "$reply[@]"
          _mydb "$@"

     This shows a completion function for a command mydb which takes two
     command arguments, add and show.  show takes no arguments, while
     the arguments for add have already been prepared in an array
     mydb_add_cmds, quite possibly by a previous call to _regex_words.

_requested [ -x ] [ -12VJ ] TAG [ NAME DESCR [ COMMAND [ ARG ... ] ]
     This function is called to decide whether a tag already registered
     by a call to _tags (see below) has been requested by the user and
     hence completion should be performed for it.  It returns status
     zero if the tag is requested and non-zero otherwise.  The function
     is typically used as part of a loop over different tags as follows:

          _tags foo bar baz
          while _tags; do
            if _requested foo; then
              ... # perform completion for foo
            fi
            ... # test the tags bar and baz in the same way
            ... # exit loop if matches were generated
          done

     Note that the test for whether matches were generated is not
     performed until the end of the _tags loop.  This is so that the
     user can set the tag-order style to specify a set of tags to be
     completed at the same time.

     If NAME and DESCR are given, _requested calls the _description
     function with these arguments together with the options passed to
     _requested.

     If COMMAND is given, the _all_labels function will be called
     immediately with the same arguments.  In simple cases this makes it
     possible to perform the test for the tag and the matching in one
     go.  For example:

          local expl ret=1
          _tags foo bar baz
          while _tags; do
            _requested foo expl 'description' \
                compadd foobar foobaz && ret=0
            ...
            (( ret )) || break
          done

     If the COMMAND is not compadd, it must nevertheless be prepared to
     handle the same options.

_retrieve_cache CACHE_IDENTIFIER
     This function retrieves completion information from the file given
     by CACHE_IDENTIFIER, stored in a directory specified by the
     cache-path style which defaults to ~/.zcompcache.  The return
     status is zero if retrieval was successful.  It will only attempt
     retrieval if the use-cache style is set, so you can call this
     function without worrying about whether the user wanted to use the
     caching layer.

     See _store_cache below for more details.

_sep_parts
     This function is passed alternating arrays and separators as
     arguments.  The arrays specify completions for parts of strings to
     be separated by the separators.  The arrays may be the names of
     array parameters or a quoted list of words in parentheses.  For
     example, with the array 'hosts=(ftp news)' the call '_sep_parts
     '(foo bar)' @ hosts' will complete the string 'f' to 'foo' and the
     string 'b@n' to 'bar@news'.

     This function accepts the compadd options '-V', '-J', '-1', '-2',
     '-n', '-X', '-M', '-P', '-S', '-r', '-R', and '-q' and passes them
     on to the compadd builtin used to add the matches.

_sequence [ -s SEP ] [ -n MAX ] [ -d ] FUNCTION [ - ] ...
     This function is a wrapper to other functions for completing items
     in a separated list.  The same function is used to complete each
     item in the list.  The separator is specified with the -s option.
     If -s is omitted it will use ','.  Duplicate values are not matched
     unless -d is specified.  If there is a fixed or maximum number of
     items in the list, this can be specified with the -n option.

     Common compadd options are passed on to the function.  It is
     possible to use compadd directly with _sequence, though _values may
     be more appropriate in this situation.

_setup TAG [ GROUP ]
     This function sets up the special parameters used by the completion
     system appropriately for the TAG given as the first argument.  It
     uses the styles list-colors, list-packed, list-rows-first,
     last-prompt, accept-exact, menu and force-list.

     The optional GROUP supplies the name of the group in which the
     matches will be placed.  If it is not given, the TAG is used as the
     group name.

     This function is called automatically from _description and hence
     is not normally called explicitly.

_store_cache CACHE_IDENTIFIER PARAM ...
     This function, together with _retrieve_cache and _cache_invalid,
     implements a caching layer which can be used in any completion
     function.  Data obtained by costly operations are stored in
     parameters; this function then dumps the values of those parameters
     to a file.  The data can then be retrieved quickly from that file
     via _retrieve_cache, even in different instances of the shell.

     The CACHE_IDENTIFIER specifies the file which the data should be
     dumped to.  The file is stored in a directory specified by the
     cache-path style which defaults to ~/.zcompcache.  The remaining
     PARAMs arguments are the parameters to dump to the file.

     The return status is zero if storage was successful.  The function
     will only attempt storage if the use-cache style is set, so you can
     call this function without worrying about whether the user wanted
     to use the caching layer.

     The completion function may avoid calling _retrieve_cache when it
     already has the completion data available as parameters.  However,
     in that case it should call _cache_invalid to check whether the
     data in the parameters and in the cache are still valid.

     See the _perl_modules completion function for a simple example of
     the usage of the caching layer.

_tags [ [ -C NAME ] TAG ... ]
     If called with arguments, these are taken to be the names of tags
     valid for completions in the current context.  These tags are
     stored internally and sorted by using the tag-order style.

     Next, _tags is called repeatedly without arguments from the same
     completion function.  This successively selects the first, second,
     etc.  set of tags requested by the user.  The return status is zero
     if at least one of the tags is requested and non-zero otherwise.
     To test if a particular tag is to be tried, the _requested function
     should be called (see above).

     If '-C NAME' is given, NAME is temporarily stored in the ARGUMENT
     field (the fifth) of the context in the curcontext parameter during
     the call to _tags; the field is restored on exit.  This allows
     _tags to use a more specific context without having to change and
     reset the curcontext parameter (which has the same effect).

_tilde_files
     Like _files, but resolve leading tildes according to the rules of
     filename expansion, so the suggested completions don't start with a
     '~' even if the filename on the command-line does.

_values [ -O NAME ] [ -s SEP ] [ -S SEP ] [ -wC ] DESC SPEC ...
     This is used to complete arbitrary keywords (values) and their
     arguments, or lists of such combinations.

     If the first argument is the option '-O NAME', it will be used in
     the same way as by the _arguments function.  In other words, the
     elements of the NAME array will be passed to compadd when executing
     an action.

     If the first argument (or the first argument after '-O NAME') is
     '-s', the next argument is used as the character that separates
     multiple values.  This character is automatically added after each
     value in an auto-removable fashion (see below); all values
     completed by '_values -s' appear in the same word on the command
     line, unlike completion using _arguments.  If this option is not
     present, only a single value will be completed per word.

     Normally, _values will only use the current word to determine which
     values are already present on the command line and hence are not to
     be completed again.  If the -w option is given, other arguments are
     examined as well.

     The first non-option argument, DESC, is used as a string to print
     as a description before listing the values.

     All other arguments describe the possible values and their
     arguments in the same format used for the description of options by
     the _arguments function (see above).  The only differences are that
     no minus or plus sign is required at the beginning, values can have
     only one argument, and the forms of action beginning with an equal
     sign are not supported.

     The character separating a value from its argument can be set using
     the option -S (like -s, followed by the character to use as the
     separator in the next argument).  By default the equals sign will
     be used as the separator between values and arguments.

     Example:

          _values -s , 'description' \
                  '*foo[bar]' \
                  '(two)*one[number]:first count:' \
                  'two[another number]::second count:(1 2 3)'

     This describes three possible values: 'foo', 'one', and 'two'.  The
     first is described as 'bar', takes no argument and may appear more
     than once.  The second is described as 'number', may appear more
     than once, and takes one mandatory argument described as 'first
     count'; no action is specified, so it will not be completed.  The
     '(two)' at the beginning says that if the value 'one' is on the
     line, the value 'two' will no longer be considered a possible
     completion.  Finally, the last value ('two') is described as
     'another number' and takes an optional argument described as
     'second count' for which the completions (to appear after an '=')
     are '1', '2', and '3'.  The _values function will complete lists of
     these values separated by commas.

     Like _arguments, this function temporarily adds another context
     name component to the arguments element (the fifth) of the current
     context while executing the ACTION.  Here this name is just the
     name of the value for which the argument is completed.

     The style verbose is used to decide if the descriptions for the
     values (but not those for the arguments) should be printed.

     The associative array val_args is used to report values and their
     arguments; this works similarly to the opt_args associative array
     used by _arguments.  Hence the function calling _values should
     declare the local parameters state, state_descr, line, context and
     val_args:

          local context state state_descr line
          typeset -A val_args

     when using an action of the form '->STRING'.  With this function
     the context parameter will be set to the name of the value whose
     argument is to be completed.  Note that for _values, the state and
     state_descr are scalars rather than arrays.  Only a single matching
     state is returned.

     Note also that _values normally adds the character used as the
     separator between values as an auto-removable suffix (similar to a
     '/' after a directory).  However, this is not possible for a
     '->STRING' action as the matches for the argument are generated by
     the calling function.  To get the usual behaviour, the calling
     function can add the separator X as a suffix by passing the options
     '-qS X' either directly or indirectly to compadd.

     The option -C is treated in the same way as it is by _arguments.
     In that case the parameter curcontext should be made local instead
     of context (as described above).

_wanted [ -x ] [ -C NAME ] [ -12VJ ] TAG NAME DESCR COMMAND [ ARG ...]
     In many contexts, completion can only generate one particular set
     of matches, usually corresponding to a single tag.  However, it is
     still necessary to decide whether the user requires matches of this
     type.  This function is useful in such a case.

     The arguments to _wanted are the same as those to _requested, i.e.
     arguments to be passed to _description.  However, in this case the
     COMMAND is not optional; all the processing of tags, including the
     loop over both tags and tag labels and the generation of matches,
     is carried out automatically by _wanted.

     Hence to offer only one tag and immediately add the corresponding
     matches with the given description:

          local expl
          _wanted tag expl 'description' \
              compadd -- MATCH1 MATCH2...

     See also the use of _wanted in the example function in *note
     Dynamic named directories::.

     Note that, as for _requested, the COMMAND must be able to accept
     options to be passed down to compadd.

     Like _tags this function supports the -C option to give a different
     name for the argument context field.  The -x option has the same
     meaning as for _description.

_widgets [ -g PATTERN ]
     This function completes names of zle widgets (see *note Zle
     Widgets::).  The PATTERN, if present, is matched against values of
     the $widgets special parameter, documented in *note The
     zsh/zleparameter Module::.

