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367 lines
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367 lines
17 KiB
Plaintext
*pi_matchit.txt* Extended "%" matching
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For Vim version 6.3. Last change: 2017 May 14
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*matchit* *matchit.vim*
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1. Extended matching with "%" |matchit-intro|
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2. Activation |matchit-activate|
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3. Configuration |matchit-configure|
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4. Supporting a New Language |matchit-newlang|
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5. Known Bugs and Limitations |matchit-bugs|
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The functionality mentioned here is a plugin, see |add-plugin|.
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You can avoid loading this plugin by setting the "loaded_matchit" variable
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in your |vimrc| file: >
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:let loaded_matchit = 1
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==============================================================================
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1. Extended matching with "%" *matchit-intro*
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*matchit-%*
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% Cycle forward through matching groups, such as "if", "else", "endif",
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as specified by |b:match_words|.
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*g%* *v_g%* *o_g%*
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g% Cycle backwards through matching groups, as specified by
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|b:match_words|. For example, go from "if" to "endif" to "else".
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*[%* *v_[%* *o_[%*
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[% Go to [count] previous unmatched group, as specified by
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|b:match_words|. Similar to |[{|.
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*]%* *v_]%* *o_]%*
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]% Go to [count] next unmatched group, as specified by
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|b:match_words|. Similar to |]}|.
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*a%* *v_a%*
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a% In Visual mode, select the matching group, as specified by
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|b:match_words|, containing the cursor. Similar to |v_a[|.
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A [count] is ignored, and only the first character of the closing
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pattern is selected.
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In Vim, as in plain vi, the percent key, |%|, jumps the cursor from a brace,
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bracket, or paren to its match. This can be configured with the 'matchpairs'
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option. The matchit plugin extends this in several ways:
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You can match whole words, such as "if" and "endif", not just
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single characters. You can also specify a |regular-expression|.
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You can define groups with more than two words, such as "if",
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"else", "endif". Banging on the "%" key will cycle from the "if" to
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the first "else", the next "else", ..., the closing "endif", and back
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to the opening "if". Nested structures are skipped. Using |g%| goes
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in the reverse direction.
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By default, words inside comments and strings are ignored, unless
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the cursor is inside a comment or string when you type "%". If the
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only thing you want to do is modify the behavior of "%" so that it
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behaves this way, you do not have to define |b:match_words|, since the
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script uses the 'matchpairs' option as well as this variable.
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See |matchit-details| for details on what the script does, and |b:match_words|
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for how to specify matching patterns.
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MODES: *matchit-modes* *matchit-v_%* *matchit-o_%*
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Mostly, % and related motions (|g%| and |[%| and |]%|) work just like built-in
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motion commands in |Operator-pending| and |Visual| modes. However, you
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cannot make these motions |linewise| or |characterwise|, since the |:omap|s
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that define them start with "v" in order to make the default behavior
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inclusive. (See |o_v|.) In other words, "dV%" will not work. The
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work-around is to go through Visual mode: "V%d" will work.
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LANGUAGES: *matchit-languages*
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Currently, the following languages are supported: Ada, ASP with VBS, Csh,
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DTD, Entity, Essbase, Fortran, HTML, JSP (same as HTML), LaTeX, Lua, Pascal,
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SGML, Shell, Tcsh, Vim, XML. Other languages may already have support via
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the default |filetype-plugin|s in the standard vim distribution.
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To support a new language, see |matchit-newlang| below.
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DETAILS: *matchit-details* *matchit-parse*
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Here is an outline of what matchit.vim does each time you hit the "%" key. If
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there are backrefs in |b:match_words| then the first step is to produce a
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version in which these back references have been eliminated; if there are no
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backrefs then this step is skipped. This step is called parsing. For
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example, "\(foo\|bar\):end\1" is parsed to yield
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"\(foo\|bar\):end\(foo\|bar\)". This can get tricky, especially if there are
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nested groups. If debugging is turned on, the parsed version is saved as
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|b:match_pat|.
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*matchit-choose*
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Next, the script looks for a word on the current line that matches the pattern
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just constructed. It includes the patterns from the 'matchpairs' option.
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The goal is to do what you expect, which turns out to be a little complicated.
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The script follows these rules:
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Insist on a match that ends on or after the cursor.
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Prefer a match that includes the cursor position (that is, one that
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starts on or before the cursor).
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Prefer a match that starts as close to the cursor as possible.
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If more than one pattern in |b:match_words| matches, choose the one
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that is listed first.
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Examples:
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Suppose you >
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:let b:match_words = '<:>,<tag>:</tag>'
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< and hit "%" with the cursor on or before the "<" in "a <tag> is born".
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The pattern '<' comes first, so it is preferred over '<tag>', which
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also matches. If the cursor is on the "t", however, then '<tag>' is
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preferred, because this matches a bit of text containing the cursor.
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If the two groups of patterns were reversed then '<' would never be
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preferred.
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Suppose you >
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:let b:match_words = 'if:end if'
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< (Note the space!) and hit "%" with the cursor at the end of "end if".
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Then "if" matches, which is probably not what you want, but if the
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cursor starts on the "end " then "end if" is chosen. (You can avoid
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this problem by using a more complicated pattern.)
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If there is no match, the cursor does not move. (Before version 1.13 of the
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script, it would fall back on the usual behavior of |%|). If debugging is
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turned on, the matched bit of text is saved as |b:match_match| and the cursor
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column of the start of the match is saved as |b:match_col|.
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Next, the script looks through |b:match_words| (original and parsed versions)
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for the group and pattern that match. If debugging is turned on, the group is
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saved as |b:match_ini| (the first pattern) and |b:match_tail| (the rest). If
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there are backrefs then, in addition, the matching pattern is saved as
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|b:match_word| and a table of translations is saved as |b:match_table|. If
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there are backrefs, these are determined from the matching pattern and
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|b:match_match| and substituted into each pattern in the matching group.
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The script decides whether to search forwards or backwards and chooses
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arguments for the |searchpair()| function. Then, the cursor is moved to the
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start of the match, and |searchpair()| is called. By default, matching
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structures inside strings and comments are ignored. This can be changed by
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setting |b:match_skip|.
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==============================================================================
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2. Activation *matchit-activate*
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For a new language, you can add a line such as >
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let b:match_words = '\<foo\>:\<bar\>'
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to the corresponding |filetype-plugin|. See |b:match_words| below for how
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this variable is interpreted.
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==============================================================================
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3. Configuration *matchit-configure*
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There are several variables that govern the behavior of matchit.vim. Note
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that these are variables local to the buffer, not options, so use |:let| to
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define them, not |:set|. Some of these variables have values that matter; for
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others, it only matters whether the variable has been defined. All of these
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can be defined in the |filetype-plugin| or autocommand that defines
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|b:match_words| or "on the fly."
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The main variable is |b:match_words|. It is described in the section below on
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supporting a new language.
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*MatchError* *matchit-hl* *matchit-highlight*
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MatchError is the highlight group for error messages from the script. By
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default, it is linked to WarningMsg. If you do not want to be bothered by
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error messages, you can define this to be something invisible. For example,
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if you use the GUI version of Vim and your command line is normally white, you
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can do >
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:hi MatchError guifg=white guibg=white
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<
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*b:match_ignorecase*
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If you >
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:let b:match_ignorecase = 1
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then matchit.vim acts as if 'ignorecase' is set: for example, "end" and "END"
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are equivalent. If you >
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:let b:match_ignorecase = 0
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then matchit.vim treats "end" and "END" differently. (There will be no
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b:match_infercase option unless someone requests it.)
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*b:match_debug*
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Define b:match_debug if you want debugging information to be saved. See
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|matchit-debug|, below.
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*b:match_skip*
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If b:match_skip is defined, it is passed as the skip argument to
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|searchpair()|. This controls when matching structures are skipped, or
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ignored. By default, they are ignored inside comments and strings, as
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determined by the |syntax| mechanism. (If syntax highlighting is turned off,
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nothing is skipped.) You can set b:match_skip to a string, which evaluates to
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a non-zero, numerical value if the match is to be skipped or zero if the match
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should not be skipped. In addition, the following special values are
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supported by matchit.vim:
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s:foo becomes (current syntax item) =~ foo
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S:foo becomes (current syntax item) !~ foo
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r:foo becomes (line before cursor) =~ foo
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R:foo becomes (line before cursor) !~ foo
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(The "s" is meant to suggest "syntax", and the "r" is meant to suggest
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"regular expression".)
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Examples:
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You can get the default behavior with >
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:let b:match_skip = 's:comment\|string'
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<
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If you want to skip matching structures unless they are at the start
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of the line (ignoring whitespace) then you can >
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:let b:match_skip = 'R:^\s*'
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< Do not do this if strings or comments can span several lines, since
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the normal syntax checking will not be done if you set b:match_skip.
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In LaTeX, since "%" is used as the comment character, you can >
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:let b:match_skip = 'r:%'
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< Unfortunately, this will skip anything after "\%", an escaped "%". To
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allow for this, and also "\\%" (an escaped backslash followed by the
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comment character) you can >
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:let b:match_skip = 'r:\(^\|[^\\]\)\(\\\\\)*%'
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<
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See the $VIMRUNTIME/ftplugin/vim.vim for an example that uses both
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syntax and a regular expression.
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==============================================================================
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4. Supporting a New Language *matchit-newlang*
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*b:match_words*
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In order for matchit.vim to support a new language, you must define a suitable
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pattern for |b:match_words|. You may also want to set some of the
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|matchit-configure| variables, as described above. If your language has a
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complicated syntax, or many keywords, you will need to know something about
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Vim's |regular-expression|s.
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The format for |b:match_words| is similar to that of the 'matchpairs' option:
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it is a comma (,)-separated list of groups; each group is a colon(:)-separated
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list of patterns (regular expressions). Commas and backslashes that are part
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of a pattern should be escaped with backslashes ('\:' and '\,'). It is OK to
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have only one group; the effect is undefined if a group has only one pattern.
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A simple example is >
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:let b:match_words = '\<if\>:\<endif\>,'
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\ . '\<while\>:\<continue\>:\<break\>:\<endwhile\>'
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(In Vim regular expressions, |/\<| and |/\>| denote word boundaries. Thus "if"
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matches the end of "endif" but "\<if\>" does not.) Then banging on the "%"
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key will bounce the cursor between "if" and the matching "endif"; and from
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"while" to any matching "continue" or "break", then to the matching "endwhile"
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and back to the "while". It is almost always easier to use |literal-string|s
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(single quotes) as above: '\<if\>' rather than "\\<if\\>" and so on.
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Exception: If the ":" character does not appear in b:match_words, then it is
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treated as an expression to be evaluated. For example, >
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:let b:match_words = 'GetMatchWords()'
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allows you to define a function. This can return a different string depending
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on the current syntax, for example.
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Once you have defined the appropriate value of |b:match_words|, you will
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probably want to have this set automatically each time you edit the
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appropriate file type. The recommended way to do this is by adding the
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definition to a |filetype-plugin| file.
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Tips: Be careful that your initial pattern does not match your final pattern.
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See the example above for the use of word-boundary expressions. It is usually
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better to use ".\{-}" (as many as necessary) instead of ".*" (as many as
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possible). See |/\{-|. For example, in the string "<tag>label</tag>", "<.*>"
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matches the whole string whereas "<.\{-}>" and "<[^>]*>" match "<tag>" and
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"</tag>".
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*matchit-spaces* *matchit-s:notend*
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If "if" is to be paired with "end if" (Note the space!) then word boundaries
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are not enough. Instead, define a regular expression s:notend that will match
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anything but "end" and use it as follows: >
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:let s:notend = '\%(\<end\s\+\)\@<!'
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:let b:match_words = s:notend . '\<if\>:\<end\s\+if\>'
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< *matchit-s:sol*
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This is a simplified version of what is done for Ada. The s:notend is a
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|script-variable|. Similarly, you may want to define a start-of-line regular
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expression >
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:let s:sol = '\%(^\|;\)\s*'
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if keywords are only recognized after the start of a line or after a
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semicolon (;), with optional white space.
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*matchit-backref* *matchit-\1*
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In any group, the expressions `\1`, `\2`, ..., `\9` (see |/\1|) refer to parts of the
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INITIAL pattern enclosed in escaped parentheses. These are referred to as
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back references, or backrefs. For example, >
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:let b:match_words = '\<b\(o\+\)\>:\(h\)\1\>'
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means that "bo" pairs with "ho" and "boo" pairs with "hoo" and so on. Note
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that "\1" does not refer to the "\(h\)" in this example. If you have
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"\(nested \(parentheses\)\) then "\d" refers to the d-th "\(" and everything
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up to and including the matching "\)": in "\(nested\(parentheses\)\)", "\1"
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refers to everything and "\2" refers to "\(parentheses\)". If you use a
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variable such as `s:notend` or `s:sol` in the previous paragraph then remember
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to count any "\(" patterns in this variable. You do not have to count groups
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defined by |/\%(\)|.
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It should be possible to resolve back references from any pattern in the
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group. For example, >
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:let b:match_words = '\(foo\)\(bar\):more\1:and\2:end\1\2'
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would not work because "\2" cannot be determined from "morefoo" and "\1"
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cannot be determined from "andbar". On the other hand, >
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:let b:match_words = '\(\(foo\)\(bar\)\):\3\2:end\1'
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should work (and have the same effect as "foobar:barfoo:endfoobar"), although
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this has not been thoroughly tested.
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You can use |/zero-width| patterns such as |/\@<=| and |/\zs|. (The latter has
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not been thouroughly tested in matchit.vim.) For example, if the keyword "if"
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must occur at the start of the line, with optional white space, you might use
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the pattern "\(^\s*\)\@<=if" so that the cursor will end on the "i" instead of
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at the start of the line. For another example, if HTML had only one tag then
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one could >
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:let b:match_words = '<:>,<\@<=tag>:<\@<=/tag>'
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so that "%" can bounce between matching "<" and ">" pairs or (starting on
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"tag" or "/tag") between matching tags. Without the |/\@<=|, the script would
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bounce from "tag" to the "<" in "</tag>", and another "%" would not take you
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back to where you started.
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DEBUGGING *matchit-debug* *:MatchDebug*
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If you are having trouble figuring out the appropriate definition of
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|b:match_words| then you can take advantage of the same information I use when
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debugging the script. This is especially true if you are not sure whether
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your patterns or my script are at fault! To make this more convenient, I have
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made the command :MatchDebug, which defines the variable |b:match_debug| and
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creates a Matchit menu. This menu makes it convenient to check the values of
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the variables described below. You will probably also want to read
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|matchit-details| above.
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Defining the variable |b:match_debug| causes the script to set the following
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variables, each time you hit the "%" key. Several of these are only defined
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if |b:match_words| includes backrefs.
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*b:match_pat*
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The b:match_pat variable is set to |b:match_words| with backrefs parsed.
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*b:match_match*
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The b:match_match variable is set to the bit of text that is recognized as a
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match.
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*b:match_col*
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The b:match_col variable is set to the cursor column of the start of the
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matching text.
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*b:match_wholeBR*
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The b:match_wholeBR variable is set to the comma-separated group of patterns
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that matches, with backrefs unparsed.
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*b:match_iniBR*
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The b:match_iniBR variable is set to the first pattern in |b:match_wholeBR|.
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*b:match_ini*
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The b:match_ini variable is set to the first pattern in |b:match_wholeBR|,
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with backrefs resolved from |b:match_match|.
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*b:match_tail*
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The b:match_tail variable is set to the remaining patterns in
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|b:match_wholeBR|, with backrefs resolved from |b:match_match|.
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*b:match_word*
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The b:match_word variable is set to the pattern from |b:match_wholeBR| that
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matches |b:match_match|.
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*b:match_table*
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The back reference '\'.d refers to the same thing as '\'.b:match_table[d] in
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|b:match_word|.
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==============================================================================
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5. Known Bugs and Limitations *matchit-bugs*
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The various |:vmap|s defined in the script (%, |g%|, |[%|, |]%|, |a%|) may
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have undesired effects in Select mode |Select-mode-mapping|. At least, if you
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want to replace the selection with any character in "ag%[]" there will be a
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pause of |'updatetime'| first. E.g., "yV%" would normally work linewise, but
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the plugin mapping makes it characterwise.
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It would be nice if "\0" were recognized as the entire pattern. That is, it
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would be nice if "foo:\end\0" had the same effect as "\(foo\):\end\1".
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==============================================================================
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vim:tw=78:ts=8:noet:ft=help:norl:
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