zshcompwid(1)
NAME
zshcompwid - zsh completion widgets
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 zshcompsys(1), 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
zshcompctl(1).
Completion widgets are defined by the -C option to the zle builtin
command provided by the zsh/zle module (see zshzle(1)). 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 (see zshzle(1)), typing
that key will call the shell function `completer'. This function is
responsible for generating the possible 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.
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 Parameters
Used By The Shell in zshparam(1).
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 words 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 generated and accepted 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 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
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 matcher 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.
COMPLETION BUILTIN COMMANDS
compadd [ -akqQfenUlo12C ] [ -F array ]
[-P prefix ] [ -S suffix ]
[-p hidden-prefix ] [ -s hidden-suffix ]
[-i ignored-prefix ] [ -I ignored-suffix ]
[-W file-prefix ] [ -d array ]
[-J name ] [ -V name ] [ -X explanation ] [ -x message ]
[-r remove-chars ] [ -R remove-func ]
[-D array ] [ -O array ] [ -A array ]
[-E number ]
[-M match-spec ] [ -- ] [ 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 status 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:
<ipre><apre><hpre><word><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. <word> is the part of the match
that should appear in the list of completions, i.e. one of the
words given at the end of the compadd command line. 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 the given
words. 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 the
match.
-p 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 -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 the match.
-i ignored-prefix
This gives a string to insert into the command line just
before any string given with the `-P' option. Without
`-P' the string is inserted before the string given with
`-p' or directly before the match.
-I ignored-suffix
Like -i, but gives an ignored suffix.
-a With this flag the words are taken as names of arrays and
the possible matches are their values. If only some
elements of the arrays are needed, the words may also
contain subscripts, as in `foo[2,-1]'.
-k With this flag the words are taken as names of
associative arrays and the possible matches are their
keys. As for -a, the words may also contain subscripts,
as in `foo[(R)*bar*]'.
-d array
This adds per-match display strings. The array should
contain one element per word given. The completion code
will then display the first element instead of the first
word, 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 words, the
leftover words will be displayed unchanged and if there
are more display strings than words, 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 This option only has an effect if used together with the
-d option. If it is 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).
-J name
Gives the name of the group of matches the words should
be stored in.
-V name
Like -J but naming an unsorted group. These are in a
different name space than groups created with the -J
flag.
-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.
-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 suffix has
been inserted and the completion accepted, 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 zshzle(1)) to
analyse and modify the command line.
-f If this flag is given, all of the matches built from
words 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
of the matches formed by the given words 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. Words matching
one of these patterns are ignored, i.e. not considered to
be possible 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 words when inserting them into the
command line.
-M match-spec
This gives local match specifications as described below
in the section `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 the words added are to be used as possible
matches, but are not to appear in the completion listing.
-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.
-O array
If this option is given, the words are not added to the
set of possible completions. Instead, matching is done
as usual and all of the words given as arguments that
match the string on the command line 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
words which match being stored in array, the strings
generated internally by the completion code are stored.
For example, with a matching specification of `-M
"L:|no="', the string `nof' on the command line and the
string `foo' as one of the words, this option stores the
string `nofoo' in the array, whereas the -O option stores
the `foo' originally given.
-D array
As with -O, the words are not added to the set of
possible completions. Instead, the completion code tests
whether each word in turn matches what is on the line.
If the nth word does not match, the nth element of the
array is removed. Elements for which the corresponding
word is matched are retained.
-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 the words
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 words to use as
matches 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 contents of the PREFIX parameter is longer than
number characters, 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.
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.
COMPLETION MATCHING CONTROL
It is possible by use of the -M option of the 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 GLOB_COMPLETE option is set or the pattern_match
of the compstate special association is set to a non-empty string.
The match-spec given as the argument to the -M option (see `Completion
Builtin Commands' above) consists of one or more matching descriptions
separated by whitespace. Each description consists of a letter
followed by a colon and 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 match-spec understood are as follows. In each case, the
form with an upper case initial character retains the string already
typed on the command line as the final result of completion, while with
a lower case initial character the string on the command line is
changed into the corresponding part of the trial completion.
m:lpat=tpat
M:lpat=tpat
Here, lpat is a pattern that matches on the command line,
corresponding to tpat which matches in the trial completion.
l:lanchor|lpat=tpat
L:lanchor|lpat=tpat
l:lanchor||ranchor=tpat
L:lanchor||ranchor=tpat
b:lpat=tpat
B:lpat=tpat
These letters are for patterns that are anchored by another
pattern on the left side. Matching for lpat and tpat is as for m
and M, but the pattern lpat matched on the command line must be
preceded by the pattern lanchor. The lanchor 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.
If no lpat is given but a ranchor is, this matches the gap
between substrings matched by lanchor and ranchor. Unlike
lanchor, the ranchor only needs to match the trial completion
string.
The b and B forms are similar to l and L with an empty anchor,
but need to match only the beginning of the word on the command
line or trial completion, respectively.
r:lpat|ranchor=tpat
R:lpat|ranchor=tpat
r:lanchor||ranchor=tpat
R:lanchor||ranchor=tpat
e:lpat=tpat
E:lpat=tpat
As l, L, b and B, with the difference that the command line and
trial completion patterns are anchored on the right side. Here
an empty ranchor and the e and E forms force the match to the
end of the command line or trial completion string.
Each lpat, tpat or 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 ! and ^ 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
ASCII lower case letter on the line match the corresponding upper case
letter in the trial completion, you can use `m:{a-z}={A-Z}' (however,
see below for the recommended form for this). More than one pair of
classes can occur, in which case the first class before the =
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 standard `[:name:]' forms described for standard shell patterns
(see the section FILENAME GENERATION in zshexpn(1)) may appear in
correspondence classes as well as normal character classes. The only
special behaviour in correspondence classes is if the form on the left
and the form on the right are each one of [:upper:], [:lower:]. In
these cases the character in the word and the character on the line
must be the same up to a difference in case. Hence to make any lower
case character on the line match the corresponding upper case character
in the trial completion you can use `m:{[:lower:]}={[:upper:]}'.
Although the matching system does not yet handle multibyte characters,
this is likely to be a future extension, at which point this syntax
will handle arbitrary alphabets; hence this form, rather than the use
of explicit ranges, is the recommended form. In other cases `[:name:]'
forms are allowed. If the two forms on the left and right are the
same, the characters must match exactly. In remaining cases, the
corresponding tests are applied to both characters, but they are not
otherwise constrained; any matching character in one set goes with any
matching character in the other set: this is equivalent to the
behaviour of ordinary character classes.
The pattern tpat may also be one or two stars, `*' or `**'. 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); in the case of a single star, the 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.
With two stars, substrings matched by the anchor can be matched, too.
Examples:
The keys of the options association defined by the parameter module are
the option names in all-lower-case form, without underscores, and
without the optional no at the beginning even though the builtins
setopt and unsetopt understand option names with upper case letters,
underscores, and the optional no. The following alters the matching
rules so that the prefix no and any underscore are ignored when trying
to match the trial completions generated and upper case letters on the
line match the corresponding lower case letters in the words:
compadd -M 'L:|[nN][oO]= M:_= M:{[:upper:]}={[:lower:]}' - \
${(k)options}
The first part says that the pattern `[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 upper case letter on the line
matches the corresponding lower case letter in the word. The use of the
upper case forms of the specification characters (L and M) guarantees
that what has already been typed on the command line (in particular the
prefix no) will not be deleted.
Note that the use of L in the first part means that it matches only
when at the beginning of both the command line string and the trial
completion. I.e., the string `_NO_f' would not be completed to
`_NO_foo', nor would `NONO_f' be completed to `NONO_foo' because of the
leading underscore or the second `NO' on the line which makes the
pattern fail even though they are otherwise ignored. To fix this, one
would use `B:[nN][oO]=' instead of the first part. As described above,
this matches at the beginning of the trial completion, independent of
other characters or substrings at the beginning of the command line
word which are ignored by the same or other match-specs.
The second example makes completion case insensitive. This is just the
same as in the option example, except here we wish to retain the
characters in the list of completions:
compadd -M 'm:{[:lower:]}={[:upper:]}' ...
This makes lower case letters match their upper case counterparts. To
make upper case letters match the lower case forms as well:
compadd -M 'm:{[:lower:][:upper:]}={[:upper:][:lower:]}' ...
A nice example for the use of * patterns is partial word completion.
Sometimes you would like to make strings like `c.s.u' complete to
strings like `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. `comp', `source' and `unix' in
this example, is to be completed from separate sets of matches is a
different problem to be solved by the implementation of the completion
widget. The example can be handled by:
compadd -M 'r:|.=* r:|=*' \
- comp.sources.unix comp.sources.misc ...
The first specification says that lpat is the empty string, while
anchor is a dot; tpat is *, so this can match anything except for the
`.' from the anchor in the trial completion word. So in `c.s.u', the
matcher sees `c', followed by the empty string, followed by the anchor
`.', and likewise for the second dot, and replaces the empty strings
before the anchors, giving `c[omp].s[ources].u[nix]', where the last
part of the completion is just as normal.
With the pattern shown above, the string `c.u' could not be completed
to `comp.sources.unix' because the single star means that no dot
(matched by the anchor) can be skipped. By using two stars as in
`r:|.=**', however, `c.u' could be completed to `comp.sources.unix'.
This also shows that in some cases, especially if the anchor is a real
pattern, like a character class, the form with two stars may result in
more matches than one would like.
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
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 than 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 `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
compadd -M 'r:|[.,_-]=* r:|=*' ...
allows one to complete words with abbreviations before any of the
characters in the square brackets. For example, to complete
veryverylongfile.c rather than veryverylongheader.h with the above in
effect, you can just type very.c before attempting completion.
The specifications with both a left and a right anchor are useful to
complete partial words whose parts are not separated by some special
character. For example, in some places strings have to be completed
that are formed `LikeThis' (i.e. the separate parts are determined by a
leading upper case letter) or maybe one has to complete strings with
trailing numbers. Here one could use the simple form with only one
anchor as in:
compadd -M 'r:|[[:upper:]0-9]=* r:|=*' LikeTHIS FooHoo 5foo123 5bar234
But with this, the string `H' would neither complete to `FooHoo' nor to
`LikeTHIS' because in each case there is an upper case letter before
the `H' and that is matched by the anchor. Likewise, a `2' would not be
completed. In both cases this could be changed by using
`r:|[[:upper:]0-9]=**', but then `H' completes to both `LikeTHIS' and
`FooHoo' and a `2' matches the other strings because characters can be
inserted before every upper case letter and digit. To avoid this one
would use:
compadd -M 'r:[^[:upper:]0-9]||[[:upper:]0-9]=** r:|=*' \
LikeTHIS FooHoo foo123 bar234
By using these two anchors, a `H' matches only upper case `H's that are
immediately preceded by something matching the left anchor
`[^[:upper:]0-9]'. The effect is, of course, that `H' matches only the
string `FooHoo', a `2' matches only `bar234' and so on.
When using the completion system (see zshcompsys(1)), users can define
match specifications that are to be used for specific contexts by using
the matcher and matcher-list styles. The values for the latter will be
used everywhere.
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.
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