path: root/Doc/Zsh/compwid.yo

texinode(Completion Widgets)(Programmable Completion Using compctl)(Zsh Line Editor)(Top)
chapter(Completion Widgets)
cindex(completion, widgets)
cindex(completion, programmable)
cindex(completion, controlling)
sect(Description)
Completion widgets are defined by the tt(-C) option to the tt(zle)
builtin command provided by the tt(zle) module (see
ifzman(zmanref(zshzle))\
ifnzman(noderef(The zle Module))\
). For example,

example(zle -C complete expand-or-complete completer)

defines a widget named tt(complete). When this widget is bound to a key
using the tt(bindkey) builtin command defined in the tt(zle) module
(see 
ifzman(zmanref(zshzle))\
ifnzman(noderef(Zsh Line Editor))\
), typing that key will call the shell function tt(completer). This
function is responsible for generating the possible matches using the
builtins described below. Once the function returns, the completion code
takes over control again and treats the matches as the builtin widget
tt(expand-or-complete) would do.  For this second argument, the name of any
of the builtin widgets that handle completions can be given:
tt(complete-word), tt(expand-or-complete),
tt(expand-or-complete-prefix), tt(menu-complete),
tt(menu-expand-or-complete), tt(reverse-menu-complete),
tt(list-choices), or tt(delete-char-or-list).  Note that this will still
work even if the widget in question has been rebound.

startmenu()
menu(Special Parameters)
menu(Builtin Commands)
menu(Condition Codes)
menu(Matching Control)
menu(Examples)
endmenu()

texinode(Special Parameters)(Builtin Commands)()(Completion Widgets)
sect(Special Parameters)

Inside completion widgets, and any functions called from those, some
parameters have special meaning; outside these function 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 tt(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.

startitem()
vindex(words)
item(tt(words))(
This array contains the words present on the command line currently being
edited.
)
vindex(CURRENT)
item(tt(CURRENT))(
This is the number of the current word, i.e. the word the cursor is
currently on in the tt(words) array.  Note that this value is only
correct if the tt(ksharrays) options is not set.
)
vindex(PREFIX)
item(tt(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.
)
vindex(IPREFIX)
item(tt(IPREFIX))(
Initially this will be set to the empty string.  It functions like
tt(PREFIX), and gives a string which precedes the one in tt(PREFIX) and is
not considered part of the list of matches.  Typically, a string is
transferred from the beginning of tt(PREFIX) to the end of tt(IPREFIX), for
example:

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 tt(compset) builtin, see below.
)
vindex(QIPREFIX)
item(tt(QIPREFIX))(
This parameter is read-only and contains the quoted string up to the
word being completed. E.g. when completing `tt("foo)', this parameter
contains the double quote. If the tt(-q) option of tt(compset) is used 
(see below), and the original string was `tt("foo bar)' with the
cursor on the `tt(bar)', this parameter contains `tt("foo )'.
)
vindex(SUFFIX)
item(tt(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 tt(COMPLETE_IN_WORD) is
set, as otherwise the whole word on the command line is treated as a
prefix.
)
vindex(ISUFFIX)
item(tt(ISUFFIX))(
As tt(IPREFIX), but for a suffix that should not be considered part
of the matches; note that the tt(ISUFFIX) string follows the tt(SUFFIX)
string.
)
vindex(QISUFFIX)
item(tt(QISUFFIX))(
Like tt(QIPREFIX), but containing the suffix.
)
vindex(compstate)
cindex(completion widgets, examining and setting state in)
item(tt(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:

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

startitem()
item(tt(command))(
when completing for a normal command (either in a command position or for
an argument of the command).
)
item(tt(redirect))(
when completing after a redirection operator.
)
item(tt(condition))(
when completing inside a `tt([[)...tt(]])' conditional expression; in
this case the tt(words) array contains the words inside the
conditional expression.
)
item(tt(math))(
when completing in a mathematical environment such as a
`tt(LPAR()LPAR())...tt(RPAR()RPAR())' construct.
)
item(tt(value))(
when completing the value of a parameter assignment.
)
item(tt(array_value))(
when completing inside the value of an array parameter assignment; in
this case the tt(words) array contains the words inside the parentheses.
)
item(tt(subscript))(
when completing inside a parameter subscript.
)
item(tt(parameter))(
when completing the name of a parameter in a parameter expansion beginning
with tt($) but not tt(${).
)
item(tt(brace_parameter))(
when completing the name of a parameter in a parameter expansion beginning
with tt(${).
)
enditem()
)
item(tt(vared))(
If completion is called while editing a line using the tt(vared)
builtin, the value of this key is set to the name of the parameter
given as argument to tt(vared). If tt(vared) is not currently used,
this key is unset.
)
item(tt(parameter))(
The name of the parameter when completing in a subscript or in the
value of a parameter assignment.
)
item(tt(redirect))(
The redirection operator when completing in a redirection position,
i.e. one of tt(<), tt(>), etc.
)
item(tt(quoting))(
When completing inside single quotes, this is set to the string
tt(single); inside double quotes, the string
tt(double); inside backticks, the string tt(backtick).
Otherwise it is unset.
)
item(tt(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.
)
item(tt(nmatches))(
The number of matches generated and accepted by the completion code so
far, excluding those matches that are only accepted by ignoring the
tt(fignore) parameter and the tt(-a) option of the tt(compadd) builtin 
command.
)
item(tt(alternate_nmatches))(
Like tt(nmatches), but counts only matches in the alternate set. I.e. file
names with one of the suffixes from the tt(fignore) array and matches
put into the alternate set using the tt(-a) option of the tt(compadd)
builtin command (see below) are not counted.
)
item(tt(matcher))(
When completion is performed with a global match specification as defined
by

indent(tt(compmatchers=)tt(LPAR()) var(spec1 ... specN ...) tt(RPAR()))

this gives the number of the specification string currently in use.
In this case, matching is performed with each specification in turn.
)
item(tt(matcher_string))(
The global match specification string var(specN) currently used.
)
item(tt(total_matchers))(
The total number of global match specifications.
)
item(tt(restore))(
This is set to tt(auto) before a function is entered, which forces the
special parameters mentioned above (tt(words), tt(CURRENT), tt(PREFIX),
tt(IPREFIX), tt(SUFFIX), and tt(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.
)
item(tt(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
tt(list), they will always be listed; if it begins with tt(autolist)
or tt(ambiguous), they will be listed when the tt(AUTO_LIST) or
tt(LIST_AMBIGUOUS) options respectively would normally cause them to
be.  Finally, if the value contains the string tt(explanations), only
the explanation strings, if any, will be listed. It will be set
appropriately on entry to a completion widget and may be changed
there.
)
item(tt(force_list))(
If the value for the tt(list) key is tt(autolist) or tt(ambiguous), the list will
normally be shown only if there are at least two matches in the
list. Setting tt(force_list) to an non-empty string forces the list to be
shown even if there is only one match.
)
item(tt(list_max))(
Initially this is set to the value of the tt(LISTMAX) parameter.
It may be set to any other numeric value; when the widget exits this value
will be used in the same way as the value of tt(LISTMAX).
)
item(tt(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 tt(BLINES)
special parameter.
)
item(tt(last_prompt))(
If this is set to an non-empty string, 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 tt(ALWAYS_LAST_PROMPT) option.
)
item(tt(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 tt(unambiguous), any prefix common to all
matches is to be inserted; if set to tt(menu) or tt(automenu) the usual
behaviour of the tt(MENU_COMPLETE) or tt(AUTO_MENU) options, respectively,
is to be used.

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.
It may also be set to a string of the form `var(group):var(match)' which
specifies a match from a group of matches to be inserted, counting from 1
upwards (e.g. `tt(2:4)' specifies the fourth match of the second group).
Negative numbers count backward from the last match or group (with `tt(-1)'
selecting the last match or group) and out-of-range values are wrapped
around, so that a value of zero selects the last match or group 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.

It may also be set to tt(all), which makes all matches generated be
inserted into the line.
)
item(tt(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
tt(single) if this will happen when a single unambiguous match was inserted
or tt(match) if it will happen any time a match is inserted (for example,
by menucompletion; this is likely to be the effect of the tt(ALWAYS_TO_END)
option).

On exit, it may be set to tt(single) as above.  It may also be set to
tt(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 tt(match).
)
item(tt(old_list))(
This is set to tt(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 tt(shown).

After the widget has exited the value of this key is only used if it
was set to tt(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.
)
item(tt(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 tt(old_list), the value of this key will only be used if it is the
string tt(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 tt(insert) key specifies that another match should be
inserted, this will be inserted after the old one.
)
item(tt(exact))(
Controls the behaviour when the tt(REC_EXACT) option is set.  It will be
set to tt(accept) if an exact match would be accepted, and will be unset
otherwise.
)
item(tt(exact_string))(
The string of an exact match if one was found, otherwise unset.
)
item(tt(pattern_match))(
Locally controls the behaviour given by the tt(GLOB_COMPLETE) option.
Initially it is set to `tt(*)' if and only if the option is set.
The completion widget may set it to either of these two values, 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 `tt(*)', then
additionally a wildcard `tt(*)' is assumed at the cursor position; if
it is empty or unset, metacharacters will be treated literally.

Note that the matcher specifications given globally or to one of the
builtin commands adding matches are not used if this is set to a
non-empty string.
)
item(tt(pattern_insert))(
Normally this is set to tt(menu), which specifies that menu-completion will
be used whenever the matches were generated using pattern matching. 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 insert an
unambiguous string for the generated matches as with normal completion.
)
item(tt(unambiguous))(
This key is read-only and will always be set to the unambiguous string
the completion code has generated for all matches added so far.
)
item(tt(unambiguous_cursor))(
This gives the position the cursor would be placed at if the
unambiguous string in the tt(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.
)
enditem()
)
enditem()

texinode(Builtin Commands)(Condition Codes)(Special Parameters)(Completion Widgets)
sect(Builtin Commands)
startitem()
findex(compadd)
cindex(completion widgets, adding specified matches)
xitem(tt(compadd) [ tt(-qQfenUaml12) ] [ tt(-F) var(array) ])
xitem([ tt(-P) var(prefix) ] [ tt(-S) var(suffix) ])
xitem([ tt(-p) var(hidden-prefix) ] [ tt(-s) var(hidden-suffix) ])
xitem([ tt(-i) var(ignored-prefix) ] [ tt(-I) var(ignored-suffix) ])
xitem([ tt(-W) var(file-prefix) ] [ tt(-d) var(array) ])
xitem([ tt(-J) var(name) ] [ tt(-V) var(name) ] [ tt(-X) var(explanation) ])
xitem([ tt(-r) var(remove-chars) ] [ tt(-R) var(remove-func) ])
xitem([ tt(-M) var(match-spec) ] [ tt(-O) var(array) ] [ tt(-A) var(array) ])
item([ tt(-D) var(array) ] [ tt(--) ] [ var(words) ... ])(

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

The completion code breaks the string to complete into seven fields in
the order: 

indent(var(<ipre><apre><hpre><word><hsuf><asuf><isuf>))

The first field
is an ignored prefix taken from the command line, the contents of the
tt(IPREFIX) parameter plus the string given with the tt(-i)
option. With the tt(-U) option, only the string from the tt(-i)
option is used. The field var(<apre>) is an optional prefix string
given with the tt(-P) option.  The var(<hpre>) field is a string
that is considered part of the match but that should not be shown when 
listing completions, given with the tt(-p) option; for example,
functions that do filename generation might specify
a common path prefix this way. var(<word>) is the part of the match that
should appear in the list of completions, one of the tt(words) given at the
end. The suffixes var(<hsuf>), var(<asuf>) and var(<isuf>) correspond to
the prefixes var(<hpre>), var(<apre>) and var(<ipre>) and are given by the
options tt(-s), tt(-S) and tt(-I), respectively.

The supported flags are:

startitem()
item(tt(-P) var(prefix))(
This gives a string to be inserted before the given var(words).  The
string given is not considered as part of the match.
)
item(tt(-S) var(suffix))(
Like tt(-P) but gives a string to be inserted after the match.
)
item(tt(-p) var(hidden-prefix))(
This gives a string that should be inserted into the command line before the
match but that should not appear in the list of matches. Unless the
tt(-U) option is given, this string must be matched as part of the string
on the command line.
)
item(tt(-s) var(hidden-suffix))(
Like `tt(-p)', but gives a string to insert after the match.
)
item(tt(-i) var(ignored-prefix))(
This gives a string to insert into the command line just before any
string given with the `tt(-P)' option.  Without `tt(-P)' the string is
inserted before the string given with `tt(-p)' or directly before the
match.
)
item(tt(-I) var(ignored-suffix))(
Like tt(-i), but gives an ignored suffix.
)
item(tt(-d) var(array))(
This adds per-match display strings. The var(array) should contain one 
element per var(word) given. The completion code will then display the 
first element instead of the first var(word), and so on. The
var(array) may be given as the name of a array parameter or directly
as a space-separated list of words in parentheses.

If there are fewer display strings than var(words), the leftover
var(words) will be displayed unchanged and if there are more display
strings than var(words), the leftover display strings will be silently
ignored.
)
item(tt(-l))(
This option only has an effect if used together with the tt(-d)
options. If it is given, the display strings are listed one per line,
not arrayed in columns.
)
item(tt(-J) var(name))(
Gives the name of the group of matches the words should be stored in.
)
item(tt(-V) var(name))(
Like tt(-J) but naming a unsorted group.
)
item(tt(-1))(
If given together with the tt(-V) option, makes
only consecutive duplicates in the group be removed. Note that groups
with and without this flag are in different name spaces.
)
item(tt(-2))(
If given together with the tt(-J) or tt(-V) option, makes all
duplicates be kept. Again, groups with and without this flag are in
different name spaces.
)
item(tt(-X) var(explanation))(
The var(explanation) string will be printed with the list of matches.
)
item(tt(-q))(
The suffix given with tt(-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.
)
item(tt(-r) var(remove-chars))(
This is a more versatile form of the tt(-q) option.
The suffix given with tt(-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
var(remove-chars).  This string is parsed as a characters class and
understands the backslash sequences used by the tt(print) command.  For
example, `tt(-r "a-z\t")' removes the suffix if the next character typed
inserts a lowercase character or a TAB, and `tt(-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: `tt(\-)' stands for
all characters that insert nothing. Thus `tt(-S "=" -q)' is the same
as `tt(-S "=" -r "= \t\n\-")'.
)
item(tt(-R) var(remove-func))(
This is another form of the tt(-r) option. When a suffix 
has been inserted and the completion accepted, the function
var(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
ifzman(zmanref(zshzle))\
ifnzman(noderef(Zsh Line Editor))\
) to analyse and modify the command line.
)
item(tt(-f))(
If this flag is given, all of the matches built from var(words) are
marked as being the names of files.  They are not required to be actual
filenames, but if they are, and the option tt(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.
)
item(tt(-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 tt(AUTO_PARAM_SLASH) and tt(AUTO_PARAM_KEYS) options be used for
the matches.
)
item(tt(-W) var(file-prefix))(
This string is a pathname that will be
prepended to each of the matches formed by the given var(words) together 
with any prefix specified by the tt(-p) option to form a complete filename
for testing.  Hence it is only useful if combined with the tt(-f) flag, as
the tests will not otherwise be performed.
)
item(tt(-a))(
The completion code may
build two sets of matches: the normal one where words with one of the 
suffixes in the array parameter tt(fignore) are not considered
possible matches, and the alternate set where the words excluded
from the first set are stored. Normally only the matches in the first
set are used, but if this set is empty, the words from the alternate
set are used.

The tt(compadd) builtin does not use the tt(fignore) parameter and
normally stores all words in the first set.  With the tt(-a)-flag
given, however, the given var(words) are stored in the alternate set unless
this flag is overridden by the tt(-F) option.
)
item(tt(-F) var(array))(
Specifies an array containing suffixes in the same form as the
tt(fignore) parameter. Words with one of these suffixes are stored in
the alternate set of matches and words without one of these suffixes
are stored in the normal set.

The var(array) may be the name of an array parameter or a list of
literal suffixes enclosed in parentheses and quoted, as in `tt(-F "(.o
.h)")'. If the name of an array is given, the elements of the array are
taken as the suffixes.
)
item(tt(-Q))(
This flag instructs the completion 
code not to quote any metacharacters in the words when inserting them
into the command line.
)
item(tt(-M) var(match-spec))(
This gives local match specifications as described below in
noderef(Matching Control).
Note that they will only be used if the tt(-U) option is not given.
)
item(tt(-n))(
Specifies that the words added are to be used as possible
matches, but are not to appear in the completion listing.
)
item(tt(-U))(
If this flag is given, all words given will be accepted and no matching
will be done by the completion code. Normally this is used in
functions that do the matching themselves.
)
item(tt(-O) var(array))(
If this option is given, the var(words) are em(not) added to the set of
possible completions.  Instead, matching is done as usual and all of the
var(words) given as arguments that match the string on the command line
will be stored in the array parameter whose name is given as var(array).
)
item(tt(-A) var(array))(
As the tt(-O) option, except that instead of those of the var(words) which
match being stored in var(array), the strings generated internally by the
completion code are stored. For example,
with a matching specification of `tt(-M "L:|no=")', the string `tt(nof)'
on the command line and the string `tt(foo)' as one of the var(words), this
option stores the string `tt(nofoo)' in the array, whereas the tt(-O)
option stores the `tt(foo)' originally given.
)
item(tt(-D) var(array))(
As with tt(-O), the var(words) are not added to the set of possible
completions. Instead, the completion code tests every var(word) if 
it matches what is on the line. If the var(n)'th var(word) does not
match, the var(n)'th element of the var(array) is removed. Elements
for which the corresponding var(word) is matched are retained.
)
item(tt(-), tt(--))(
This flag ends the list of flags and options. All arguments after it
will be taken as the words to use as matches even if they begin with
hyphens.
)
enditem()
)
findex(compset)
cindex(completion widgets, modifying special parameters)
xitem(tt(compset -p) var(number))
xitem(tt(compset -P) [ var(number) ] var(pattern))
xitem(tt(compset -s) var(number))
xitem(tt(compset -S) [ var(number) ] var(pattern))
xitem(tt(compset -n) var(begin) [ var(end) ])
xitem(tt(compset -N) var(beg-pat) [ var(end-pat) ])
item(tt(compset -q))(
This command simplifies modification of the special parameters,
while its return value allows tests on them to be carried out.

The options are:

startitem()
item(tt(-p) var(number))(
If the contents of the tt(PREFIX) parameter is longer than var(number)
characters, the first var(number) characters are removed from it and
appended to the contents of the tt(IPREFIX) parameter.
)
item(tt(-P) [ var(number) ] var(pattern))(
If the value of the tt(PREFIX) parameter begins with anything that
matches the var(pattern), the matched portion is removed from
tt(PREFIX) and appended to tt(IPREFIX).

Without the optional var(number), the longest match is taken, but
if var(number) is given, anything up to the var(number)'th match is
moved.  If the var(number) is negative, the var(number)'th longest
match is moved. For example, if tt(PREFIX) contains the string
`tt(a=b=c)', then tt(compset -P '*\=') will move the string `tt(a=b=)' 
into the tt(IPREFIX) parameter, but tt(compset -P 1 '*\=') will move only
the string `tt(a=)'.
)
item(tt(-s) var(number))(
As tt(-p), but transfer the last var(number) characters from the
value of tt(SUFFIX) to the front of the value of tt(ISUFFIX).
)
item(tt(-S) [ var(number) ] var(pattern))(
As tt(-P), but match the last portion of tt(SUFFIX) and transfer the
matched portion to the front of the value of tt(ISUFFIX).
)
item(tt(-n) var(begin) [ var(end) ])(
If the current word position as specified by the parameter tt(CURRENT) 
is greater than or equal to var(begin), anything up to the
var(begin)'th word is removed from the tt(words) array and the value
of the parameter tt(CURRENT) is decremented by var(begin).

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

Both var(begin) and var(end) may be negative to count backwards
from the last element of the tt(words) array.
)
item(tt(-N) var(beg-pat) [ var(end-pat) ])(
If one of the elements of the tt(words) array before the one at the
index given by the value of the parameter tt(CURRENT) matches the
pattern var(beg-pat), all elements up to and including the matching one are
removed from the tt(words) array and the value of tt(CURRENT) is changed to
point to the same word in the changed array.

If the optional pattern var(end-pat) is also given, and there is an
element in the tt(words) array matching this pattern, the parameters
are modified only if the index of this word is higher than the one
given by the tt(CURRENT) parameter (so that the matching word has 
to be after the cursor). In this case, the words starting with the one
matching tt(end-pat) are also removed from the tt(words)
array. If tt(words) contains no word matching var(end-pat), the
testing and modification is performed as if it were not given.
)
item(tt(-q))(
The word
currently being completed is split in separate words at the spaces. The 
resulting words are stored in the tt(words) array, and tt(CURRENT),
tt(PREFIX), tt(SUFFIX), tt(QIPREFIX), and tt(QISUFFIX) are modified to
reflect the word part that is completed.
)
enditem()

In all the above cases the return value 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:

example(if compset -P '*\='; then ...)

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

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

Note that this builtin is defined by the tt(compctl) module.
)
enditem()

texinode(Condition Codes)(Matching Control)(Builtin Commands)(Completion Widgets)
sect(Condition Codes)
cindex(completion widgets, condition codes)

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

startitem()
item(tt(-prefix) [ var(number) ] var(pattern))(
true if the test for the tt(-P) option of tt(compset) would succeed.
)
item(tt(-suffix) [ var(number) ] var(pattern))(
true if the test for the tt(-S) option of tt(compset) would succeed.
)
item(tt(-after) var(beg-pat))(
true if the test of the tt(-N) option with only the var(beg-pat) given 
would succeed.
)
item(tt(-between) var(beg-pat end-pat))(
true if the test for the tt(-N) option with both patterns would succeed.
)
enditem()

texinode(Matching Control)(Examples)(Condition Codes)(Completion Widgets)
sect(Matching Control)

It is possible by use of the tt(compmatchers) special array and the
tt(-M) option of the tt(compadd) builtin command to specify how the
characters in the string to be completed (referred to here as the
command line) map onto the characters in the list of matches produced by
the completion code (referred to here as the trial completions). Note
that this is not used if the command line contains a glob pattern and
the tt(GLOB_COMPLETE) option is set.

The var(spec) consists of one or more matching descriptions separated by
whitespace. Each description consists of a letter followed by a colon,
then the patterns describing which character sequences on the line match
which character sequences in the trial completion.  Any sequence of characters not
handled in this fashion must match exactly, as usual.

The forms of var(spec) understood are as follows. In each case, the
form with an uppercase initial character retains the string already
typed on the command line as the final result of completion, while with
a lowercase initial character the string on the command line is changed
into the corresponding part of the trial completion.

startitem()
xitem(tt(m:)var(lpat)tt(=)var(tpat))
item(tt(M:)var(lpat)tt(=)var(tpat))(
Here, var(lpat) is a pattern that matches on the command line,
corresponding to var(tpat) which matches in the trial completion.
)
xitem(tt(l:)var(anchor)tt(|)var(lpat)tt(=)var(tpat))
item(tt(L:)var(anchor)tt(|)var(lpat)tt(=)var(tpat))(
These letters are for patterns that are anchored by another pattern on
the left side. Matching for var(lpat) and var(tpat) is as for tt(m) and
tt(M), but the pattern var(lpat) matched on the command line must be
preceeded by the pattern var(anchor).  The var(anchor) can be blank to
anchor the match to the start of the command line string; otherwise the
anchor can occur anywhere, but must match in both the command line and
trial completion strings.
)
xitem(tt(r:)var(lpat)tt(|)var(anchor)tt(=)var(tpat))
item(tt(R:)var(lpat)tt(|)var(anchor)tt(=)var(tpat))(
As tt(l) and tt(L) with the difference that the command line and trial
completion patterns are anchored on the right side.  Here an empty
var(anchor) forces the match to the end of the command line string.
)
enditem()

Each var(lpat), var(tpat) or var(anchor) is either an empty string or
consists of a sequence of literal characters (which may be quoted with a
backslash), question marks, character classes, and correspondence
classes; ordinary shell patterns are not used.  Literal characters match
only themselves, question marks match any character, and character
classes are formed as for globbing and match any character in the given
set.

Correspondence classes are defined like character classes, but with two
differences: they are delimited by a pair of braces, and negated classes
are not allowed, so the characters tt(!) and tt(^) have no special
meaning directly after the opening brace.  They indicate that a range of
characters on the line match a range of characters in the trial
completion, but (unlike ordinary character classes) paired according to
the corresponding position in the sequence. For example, to make any
lowercase letter on the line match the corresponding uppercase letter in
the trial completion, you can use `tt(m:{a-z}={A-Z})'.  More than one
pair of classes can occur, in which case the first class before the
tt(=) corresponds to the first after it, and so on.  If one side has
more such classes than the other side, the superfluous classes behave
like normal character classes. In anchor patterns correspondence classes
also behave like normal character classes.

The pattern var(tpat) may also be a single star, `tt(*)'. This means
that the pattern on the command line can match any number of characters
in the trial completion. In this case the pattern must be anchored (on
either side); the var(anchor) then determines how much of the trial
completion is to be included --- only the characters up to the next
appearance of the anchor will be matched.

Examples:

The keys of the tt(options) association defined by the tt(parameter)
module are the option names in all-lowercase form, without
underscores, and without the optional tt(no) at the beginning even
though the builtins tt(setopt) and tt(unsetopt) understand option names
with uppercase letters, underscores, and the optional tt(no).  The
following alters the matching rules so that the prefix tt(no) and any
underscore are ignored when trying to match the trial completions
generated and uppercase letters on the line match the corresponding
lowercase letters in the words:

example(compadd -M 'L:|[nN][oO]= M:_= M:{A-Z}={a-z}' - \ 
  ${(k)options} )

The first part says that the pattern `tt([nN][oO])' at the beginning
(the empty anchor before the pipe symbol) of the string on the
line matches the empty string in the list of words generated by
completion, so it will be ignored if present. The second part does the
same for an underscore anywhere in the command line string, and the
third part uses correspondence classes so that any
uppercase letter on the line matches the corresponding lowercase
letter in the word. The use of the uppercase forms of the
specification characters (tt(L) and tt(M)) guarantees that what has
already been typed on the command line (in particular the prefix
tt(no)) will not be deleted.

The second example makes completion case insensitive.  By setting the
tt(compmatchers) array this applies to every
completion.  This is just the same as in the option example, except
here we wish to retain the characters in the list of completions:

example(compmatchers=( 'm:{a-z}={A-Z}' ) )

This makes lowercase letters match their uppercase counterparts.
To make uppercase letters match the lowercase forms as well:

example(compmatchers=( 'm:{a-zA-Z}={A-Za-z}' ) )

A nice example for the use of tt(*) patterns is partial word
completion. Sometimes you would like to make strings like tt(c.s.u)
complete to strings like tt(comp.source.unix), i.e. the word on the
command line consists of multiple parts, separated by a dot in this
example, where each part should be completed separately --- note,
however, that the case where each part of the word, i.e. tt(comp),
tt(source) and tt(unix) in this example, is to be completed separately
is a different problem to be solved by extended completion.  The
example can be handled by:

example(compadd -M 'r:|.=* r:|=*' \ 
  - comp.sources.unix comp.sources.misc ...)

The first specification says that tt(lpat) is the empty string, while
tt(anchor) is a dot; tt(tpat) is tt(*), so this can match anything
except for the `tt(.)' from the anchor in
the trial completion word.  So in tt(c.s.u), the matcher sees tt(c),
followed by the empty string, followed by the anchor `tt(.)', and
likewise for the second dot, and replaces the empty strings before the
anchors, giving tt(c)[tt(omp)]tt(.s)[tt(ources)]tt(.u)[tt(nix)], where
the last part of the completion is just as normal.

The second specification is needed to make this work when the cursor is
in the middle of the string on the command line and the option
tt(COMPLETE_IN_WORD) is set. In this case the completion code would
normally try to match trial completions that end with the string as
typed so far, i.e. it will only insert new characters at the cursor
position rather then at the end.  However in our example we would like
the code to recognise matches which contain extra characters after the
string on the line (the tt(nix) in the example).  Hence we say that the
empty string at the end of the string on the line matches any characters
at the end of the trial completion.

More generally, the specification

example(compmatchers=( 'r:|[.,_-]=* r:|=*' ) )

allows one to complete words with abbreviations before any of the
characters in the square brackets in any completion.  For example, to
complete tt(veryverylongfile.c) rather than tt(veryverylongheader.h)
with the above in effect, you can just type tt(very.c) before attempting
completion.

The tt(compmatchers) array that defines global matching can actually 
contain any number of specification strings, unlike the case where the
tt(-M) option is used with the tt(compadd) builtin command.  In this case, when
completion is attempted for any command, the code will try the
specifications in order until one matches.  This allows one to define
simple and fast matches to be used first, more powerful matchers as a
second choice, and so on.

For example, one can make the code match trial completions that contain
the string on the command line as a substring, not just at the
beginning.  Since this might produce more matches than we want,
we arrange for it to be tried only if the matchers described above don't
produce any matches:

example(compmatchers=( 'r:|[.,_-]=* r:|=*' 'l:|=* r:|=*' ) )

Here, if the string on the command line is tt(foo.bar), the completion 
code first tries matching tt(foo)var(anything)tt(.bar)var(anything), as
with the previous example.  If that fails, the two descriptions in the
second string say that the blanks at the beginning
and end of the string on the command line can match any set of
characters at the beginning or end of the trial completion, so it will
look for var(anything)tt(foo.bar)var(anything).

texinode(Examples)()(Matching Control)(Completion Widgets)
sect(Examples)
cindex(completion widgets, examples)

The first step is to define the widget:

example(zle -C complete complete-word complete-files)

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

example(bindkey '^X\t' complete)

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

example(complete-filles LPAR()RPAR() { compadd - * })

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

For a description of the widget-based completion system provided with the
source code distribution, see
ifzman(zmanref(zshcompsys))\
ifnzman(noderef(Completion System))\
.