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<section id="ctags-optlib">
<span id="ctags-optlib-7"></span><h1>ctags-optlib<a class="headerlink" href="#ctags-optlib" title="Permalink to this headline">¶</a></h1>
<p>Universal Ctags parser definition language</p>
<dl class="field-list simple">
<dt class="field-odd">Version</dt>
<dd class="field-odd"><p>5.9.0</p>
</dd>
<dt class="field-even">Manual group</dt>
<dd class="field-even"><p>Universal Ctags</p>
</dd>
<dt class="field-odd">Manual section</dt>
<dd class="field-odd"><p>7</p>
</dd>
</dl>
<section id="synopsis">
<h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline">¶</a></h2>
<div class="line-block">
<div class="line"><strong>ctags</strong> [options] [file(s)]</div>
<div class="line"><strong>etags</strong> [options] [file(s)]</div>
</div>
</section>
<section id="description">
<h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h2>
<p><em>Exuberant Ctags</em>, the ancestor of <em>Universal Ctags</em>, has provided
the way to define a new parser from command line. Universal Ctags
extends and refines this feature. <em>optlib parser</em> is the name for such
parser in Universal Ctags. “opt” intends a parser is defined with
combination of command line options. “lib” intends an optlib parser
can be more than ad-hoc personal configuration.</p>
<p>This man page is for people who want to define an optlib parser. The
readers should read <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a> of Universal Ctags first.</p>
<p>Following options are for defining (or customizing) a parser:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">--langdef=<name></span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">--map-<LANG>=[+|-]<extension>|<pattern></span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG>=<letter>,<name>,<description></span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">--regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]</span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">--mline-regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]</span></code></p></li>
</ul>
<p>Following options are for controlling loading parser definition:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">--options=<pathname></span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">--options-maybe=<pathname></span></code></p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">--optlib-dir=[+]<directory></span></code></p></li>
</ul>
<p>The design of options and notations for defining a parser in
Exuberant Ctags may focus on reducing the number of typing by user.
Reducing the number of typing is important for users who want to
define (or customize) a parser quickly.</p>
<p>On the other hand, the design in Universal Ctags focuses on
maintainability. The notation of Universal Ctags is redundant than
that of Exuberant Ctags; the newly introduced kind should be declared
explicitly, (long) names are approved than one-letter flags
specifying kinds, and naming rules are stricter.</p>
<p>This man page explains only stable options and flags. Universal Ctags
also introduces experimental options and flags which have names starting
with <code class="docutils literal notranslate"><span class="pre">_</span></code>. For documentation on these options and flags, visit
Universal Ctags web site at <a class="reference external" href="https://ctags.io/">https://ctags.io/</a>.</p>
<section id="storing-a-parser-definition-to-a-file">
<h3>Storing a parser definition to a file<a class="headerlink" href="#storing-a-parser-definition-to-a-file" title="Permalink to this headline">¶</a></h3>
<p>Though it is possible to define a parser from command line, you don’t
want to type the same command line each time when you need the parser.
You can store options for defining a parser into a file.</p>
<p>ctags loads files (preload files) listed in “FILES”
section of <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a> at program starting up. You can put your parser
definition needed usually to the files.</p>
<p><code class="docutils literal notranslate"><span class="pre">--options=<pathname></span></code>, <code class="docutils literal notranslate"><span class="pre">--options-maybe=<pathname></span></code>, and
<code class="docutils literal notranslate"><span class="pre">--optlib-dir=[+]<directory></span></code> are for loading optlib files you need
occasionally. See “Option File Options” section of <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a> for
these options.</p>
<p>As explained in “FILES” section of <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a>, options for defining a
parser listed line by line in an optlib file. Prefixed white spaces are
ignored. A line starting with ‘#’ is treated as a comment. Escaping
shell meta character is not needed.</p>
<p>Use <code class="docutils literal notranslate"><span class="pre">.ctags</span></code> as file extension for optlib file. You can define
multiple parsers in an optlib file but it is better to make a file for
each parser definition.</p>
<p><code class="docutils literal notranslate"><span class="pre">--_echo=<msg></span></code> and <code class="docutils literal notranslate"><span class="pre">--_force-quit=<num></span></code> options are for debugging
optlib parser.</p>
</section>
<section id="overview-for-defining-a-parser">
<h3>Overview for defining a parser<a class="headerlink" href="#overview-for-defining-a-parser" title="Permalink to this headline">¶</a></h3>
<ol class="arabic">
<li><p>Design the parser</p>
<p>You need know both the target language and the ctags’
concepts (definition, reference, kind, role, field, extra). About
the concepts, <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a> of Universal Ctags may help you.</p>
</li>
<li><p>Give a name to the parser</p>
<p>Use <code class="docutils literal notranslate"><span class="pre">--langdef=<name></span></code> option. <em><name></em> is referred as <em><LANG></em> in
the later steps.</p>
</li>
<li><p>Give a file pattern or file extension for activating the parser</p>
<p>Use <code class="docutils literal notranslate"><span class="pre">--map-<LANG>=[+|-]<extension>|<pattern></span></code>.</p>
</li>
<li><p>Define kinds</p>
<p>Use <code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG>=<letter>,<name>,<description></span></code> option.
Universal Ctags introduces this option. Exuberant Ctags doesn’t
have. In Exuberant Ctags, a kind is defined as a side effect of
specifying <code class="docutils literal notranslate"><span class="pre">--regex-<LANG>=</span></code> option. So user doesn’t have a
chance to recognize how important the definition of kind.</p>
</li>
<li><p>Define patterns</p>
<p>Use <code class="docutils literal notranslate"><span class="pre">--regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]</span></code>
option for a single-line regular expression. You can also use
<code class="docutils literal notranslate"><span class="pre">--mline-regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]</span></code>
option for a multi-line regular expression.</p>
<p>As <em><kind-spec></em>, you can use the one-letter flag defined with
<code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG>=<letter>,<name>,<description></span></code> option.</p>
</li>
</ol>
</section>
</section>
<section id="options">
<h2>OPTIONS<a class="headerlink" href="#options" title="Permalink to this headline">¶</a></h2>
<dl>
<dt><code class="docutils literal notranslate"><span class="pre">--langdef=<name></span></code></dt><dd><p>Defines a new user-defined language, <em><name></em>, to be parsed with regular
expressions. Once defined, <em><name></em> may be used in other options taking
language names.</p>
<p><em><name></em> must consist of alphanumeric characters, ‘<code class="docutils literal notranslate"><span class="pre">#</span></code>’, or ‘<code class="docutils literal notranslate"><span class="pre">+</span></code>’
(‘[a-zA-Z0-9#+]+’). The graph characters other than ‘<code class="docutils literal notranslate"><span class="pre">#</span></code>’ and
‘<code class="docutils literal notranslate"><span class="pre">+</span></code>’ are disallowed (or reserved). Some of them (<code class="docutils literal notranslate"><span class="pre">[-=:{.]</span></code>) are
disallowed because they can make the command line parser of
ctags confused. The rest of them are just
reserved for future extending ctags.</p>
<p><code class="docutils literal notranslate"><span class="pre">all</span></code> is an exception. <code class="docutils literal notranslate"><span class="pre">all</span></code> as <em><name></em> is not acceptable. It is
a reserved word. See the description of
<code class="docutils literal notranslate"><span class="pre">--kinds-(<LANG>|all)=[+|-](<kinds>|*)</span></code> option in <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a> about how the
reserved word is used.</p>
<p>The names of built-in parsers are capitalized. When
ctags evaluates an option in a command line, and
chooses a parser, ctags uses the names of
parsers in a case-insensitive way. Therefore, giving a name
started from a lowercase character doesn’t help you to avoid the
parser name confliction. However, in a tags file,
ctags prints parser names in a case-sensitive
way; it prints a parser name as specified in <code class="docutils literal notranslate"><span class="pre">--langdef=<name></span></code>
option. Therefore, we recommend you to give a name started from a
lowercase character to your private optlib parser. With this
convention, people can know where a tag entry in a tag file comes
from a built-in parser or a private optlib parser.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG>=<letter>,<name>,<description></span></code></dt><dd><p>Define a kind for <em><LANG></em>.
Be not confused this with <code class="docutils literal notranslate"><span class="pre">--kinds-<LANG></span></code>.</p>
<p><em><letter></em> must be an alphabetical character (‘[a-zA-EG-Z]’)
other than “F”. “F” has been reserved for representing a file
since Exuberant Ctags.</p>
<p><em><name></em> must start with an alphabetic character, and the rest
must be alphanumeric (‘[a-zA-Z][a-zA-Z0-9]*’). Do not use
“file” as <em><name></em>. It has been reserved for representing a file
since Exuberant Ctags.</p>
<p>Note that using a number character in a <em><name></em> violates the
version 2 of tags file format though ctags
accepts it. For more detail, see <a class="reference internal" href="tags.5.html#tags-5"><span class="std std-ref">tags(5)</span></a>.</p>
<p><em><description></em> comes from any printable ASCII characters. The
exception is <code class="docutils literal notranslate"><span class="pre">{</span></code> and <code class="docutils literal notranslate"><span class="pre">\</span></code>. <code class="docutils literal notranslate"><span class="pre">{</span></code> is reserved for adding flags
this option in the future. So put <code class="docutils literal notranslate"><span class="pre">\</span></code> before <code class="docutils literal notranslate"><span class="pre">{</span></code> to include
<code class="docutils literal notranslate"><span class="pre">{</span></code> to a description. To include <code class="docutils literal notranslate"><span class="pre">\</span></code> itself to a description,
put <code class="docutils literal notranslate"><span class="pre">\</span></code> before <code class="docutils literal notranslate"><span class="pre">\</span></code>.</p>
<p>Both <em><letter></em>, <em><name></em> and their combination must be unique in
a <em><LANG></em>.</p>
<p>This option is newly introduced in Universal Ctags. This option
reduces the typing defining a regex pattern with
<code class="docutils literal notranslate"><span class="pre">--regex-<LANG>=</span></code>, and keeps the consistency of kind
definitions in a language.</p>
<p>The <em><letter></em> can be used as an argument for <code class="docutils literal notranslate"><span class="pre">--kinds-<LANG></span></code>
option to enable or disable the kind. Unless <code class="docutils literal notranslate"><span class="pre">K</span></code> field is
enabled, the <em><letter></em> is used as value in the “kind” extension
field in tags output.</p>
<p>The <em><name></em> surrounded by braces can be used as an argument for
<code class="docutils literal notranslate"><span class="pre">--kind-<LANG></span></code> option. If <code class="docutils literal notranslate"><span class="pre">K</span></code> field is enabled, the <em><name></em>
is used as value in the “kind” extension field in tags output.</p>
<p>The <em><description></em> and <em><letter></em> are listed in <code class="docutils literal notranslate"><span class="pre">--list-kinds</span></code>
output. All three elements of the kind-spec are listed in
<code class="docutils literal notranslate"><span class="pre">--list-kinds-full</span></code> output. Don’t use braces in the
<em><description></em>. They will be used meta characters in the future.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]</span></code></dt><dd><p>Define a single-line regular expression.</p>
<p>The <em>/<line_pattern>/<name_pattern>/</em> pair defines a regular expression
replacement pattern, similar in style to <code class="docutils literal notranslate"><span class="pre">sed</span></code> substitution
commands, <code class="docutils literal notranslate"><span class="pre">s/regexp/replacement/</span></code>, with which to generate tags from source files mapped to
the named language, <em><LANG></em>, (case-insensitive; either a built-in
or user-defined language).</p>
<p>The regular expression, <em><line_pattern></em>, defines
an extended regular expression (roughly that used by egrep(1)),
which is used to locate a single source line containing a tag and
may specify tab characters using <code class="docutils literal notranslate"><span class="pre">\t</span></code>.</p>
<p>When a matching line is
found, a tag will be generated for the name defined by
<em><name_pattern></em>, which generally will contain the special
back-references <code class="docutils literal notranslate"><span class="pre">\1</span></code> through <code class="docutils literal notranslate"><span class="pre">\9</span></code> to refer to matching sub-expression
groups within <em><line_pattern></em>.</p>
<p>The ‘<code class="docutils literal notranslate"><span class="pre">/</span></code>’ separator characters shown in the
parameter to the option can actually be replaced by any
character. Note that whichever separator character is used will
have to be escaped with a backslash (’<code class="docutils literal notranslate"><span class="pre">\</span></code>’) character wherever it is
used in the parameter as something other than a separator. The
regular expression defined by this option is added to the current
list of regular expressions for the specified language unless the
parameter is omitted, in which case the current list is cleared.</p>
<p>Unless modified by <em><flags></em>, <em><line_pattern></em> is interpreted as a POSIX
extended regular expression. The <em><name_pattern></em> should expand for all
matching lines to a non-empty string of characters, or a warning
message will be reported unless <code class="docutils literal notranslate"><span class="pre">{placeholder}</span></code> regex flag is
specified.</p>
<p>A kind specifier (<em><kind-spec></em>) for tags matching regexp may
follow <em><name_pattern></em>, which will determine what kind of tag is
reported in the <code class="docutils literal notranslate"><span class="pre">kind</span></code> extension field (see <a class="reference internal" href="tags.5.html#tags-5"><span class="std std-ref">tags(5)</span></a>).</p>
<p><em><kind-spec></em> has two forms: <em>one-letter form</em> and <em>full form</em>.</p>
<p>The one-letter form in the form of <code class="docutils literal notranslate"><span class="pre"><letter></span></code>. It just refers a kind
<em><letter></em> defined with <code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG></span></code>. This form is recommended in
Universal Ctags.</p>
<p>The full form of <em><kind-spec></em> is in the form of
<code class="docutils literal notranslate"><span class="pre"><letter>,<name>,<description></span></code>. Either the kind <em><name></em> and/or the
<em><description></em> can be omitted. See the description of
<code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG>=<letter>,<name>,<description></span></code> option about the
elements.</p>
<p>The full form is supported only for keeping the compatibility with Exuberant
Ctags which does not have <code class="docutils literal notranslate"><span class="pre">--kinddef-<LANG></span></code> option. Supporting the
form will be removed from Universal Ctags in the future.</p>
<p>About <em><flags></em>, see “FLAGS FOR <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> OPTION”.</p>
<p>For more information on the regular expressions used by
ctags, see either the regex(5,7) man page, or
the GNU info documentation for regex (e.g. “<code class="docutils literal notranslate"><span class="pre">info</span> <span class="pre">regex</span></code>”).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--list-regex-flags</span></code></dt><dd><p>Lists the flags that can be used in <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> option.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--list-mline-regex-flags</span></code></dt><dd><p>Lists the flags that can be used in <code class="docutils literal notranslate"><span class="pre">--mline-regex-<LANG></span></code> option.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--mline-regex-<LANG>=/<line_pattern>/<name_pattern>/<kind-spec>/[<flags>]</span></code></dt><dd><p>Define a multi-line regular expression.</p>
<p>This option is similar to <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> option except the pattern is
applied to the whole file’s contents, not line by line.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--_echo=<message></span></code></dt><dd><p>Print <em><message></em> to the standard error stream. This is helpful to
understand (and debug) optlib loading feature of Universal Ctags.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">--_force-quit[=<num>]</span></code></dt><dd><p>Exits immediately when this option is processed. If <em><num></em> is used
as exit status. The default is 0. This is helpful to debug optlib
loading feature of Universal Ctags.</p>
</dd>
</dl>
<section id="flags-for-regex-lang-option">
<h3>FLAGS FOR <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> OPTION<a class="headerlink" href="#flags-for-regex-lang-option" title="Permalink to this headline">¶</a></h3>
<p>You can specify more than one flag, <code class="docutils literal notranslate"><span class="pre"><letter>|{<name>}</span></code>, at the end of <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> to
control how Universal Ctags uses the pattern.</p>
<p>Exuberant Ctags uses a <em><letter></em> to represent a flag. In
Universal Ctags, a <em><name></em> surrounded by braces (name form) can be used
in addition to <em><letter></em>. The name form makes a user reading an optlib
file easier.</p>
<p>The most of all flags newly added in Universal Ctags
don’t have the one-letter representation. All of them have only the name
representation. <code class="docutils literal notranslate"><span class="pre">--list-regex-flags</span></code> lists all the flags.</p>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">basic</span></code> (one-letter form <code class="docutils literal notranslate"><span class="pre">b</span></code>)</dt><dd><p>The pattern is interpreted as a POSIX basic regular expression.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">exclusive</span></code> (one-letter form <code class="docutils literal notranslate"><span class="pre">x</span></code>)</dt><dd><p>Skip testing the other patterns if a line is matched to this
pattern. This is useful to avoid using CPU to parse line comments.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">extend</span></code> (one-letter form <code class="docutils literal notranslate"><span class="pre">e</span></code>)</dt><dd><p>The pattern is interpreted as a POSIX extended regular
expression (default).</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">icase</span></code> (one-letter form <code class="docutils literal notranslate"><span class="pre">i</span></code>)</dt><dd><p>The regular expression is to be applied in a case-insensitive
manner.</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">placeholder</span></code></dt><dd><p>Don’t emit a tag captured with a regex pattern. The replacement
can be an empty string. See the following description of
<code class="docutils literal notranslate"><span class="pre">scope=...</span></code> flag about how this is useful.</p>
</dd>
</dl>
<p><code class="docutils literal notranslate"><span class="pre">scope=(ref|push|pop|clear|set)</span></code></p>
<blockquote>
<div><p>Specify what to do with the internal scope stack.</p>
<p>A parser programmed with <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> has a stack (scope
stack) internally. You can use it for tracking scope
information. The <code class="docutils literal notranslate"><span class="pre">scope=...</span></code> flag is for manipulating and
utilizing the scope stack.</p>
<p>If <code class="docutils literal notranslate"><span class="pre">{scope=push}</span></code> is specified, a tag captured with
<code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> is pushed to the stack. <code class="docutils literal notranslate"><span class="pre">{scope=push}</span></code>
implies <code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code>.</p>
<p>You can fill the scope field of captured tag with
<code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code>. If <code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code> flag is given,
ctags attaches the tag at the top to the tag
captured with <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> as the value for the <code class="docutils literal notranslate"><span class="pre">scope:</span></code>
field.</p>
<p>ctags pops the tag at the top of the stack when
<code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> with <code class="docutils literal notranslate"><span class="pre">{scope=pop}</span></code> is matched to the input
line.</p>
<p>Specifying <code class="docutils literal notranslate"><span class="pre">{scope=clear}</span></code> removes all the tags in the scope.
Specifying <code class="docutils literal notranslate"><span class="pre">{scope=set}</span></code> removes all the tags in the scope, and
then pushes the captured tag as <code class="docutils literal notranslate"><span class="pre">{scope=push}</span></code> does.</p>
<p>In some cases, you may want to use <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> only for its
side effects: using it only to manipulate the stack but not for
capturing a tag. In such a case, make <em><name_pattern></em> component of
<code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> option empty while specifying <code class="docutils literal notranslate"><span class="pre">{placeholder}</span></code>
as a regex flag. For example, a non-named tag can be put on
the stack by giving a regex flag “<code class="docutils literal notranslate"><span class="pre">{scope=push}{placeholder}</span></code>”.</p>
<p>You may wonder what happens if a regex pattern with
<code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code> flag matches an input line but the stack is empty,
or a non-named tag is at the top. If the regex pattern contains a
<code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code> flag and the stack is empty, the <code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code>
flag is ignored and nothing is attached to the <code class="docutils literal notranslate"><span class="pre">scope:</span></code> field.</p>
<p>If the top of the stack contains an unnamed tag,
ctags searches deeper into the stack to find the
top-most named tag. If it reaches the bottom of the stack without
finding a named tag, the <code class="docutils literal notranslate"><span class="pre">{scope=ref}</span></code> flag is ignored and
nothing is attached to the <code class="docutils literal notranslate"><span class="pre">scope:</span></code> field.</p>
<p>When a named tag on the stack is popped or cleared as the side
effect of a pattern matching, ctags attaches the
line number of the match to the <code class="docutils literal notranslate"><span class="pre">end:</span></code> field of
the named tag.</p>
<p>ctags clears all of the tags on the stack when it
reaches the end of the input source file. The line number of the
end is attached to the <code class="docutils literal notranslate"><span class="pre">end:</span></code> field of the cleared tags.</p>
</div></blockquote>
<dl class="simple">
<dt><code class="docutils literal notranslate"><span class="pre">warning=<message></span></code></dt><dd><p>print the given <em><message></em> at WARNING level</p>
</dd>
<dt><code class="docutils literal notranslate"><span class="pre">fatal=<message></span></code></dt><dd><p>print the given <em><message></em> and exit</p>
</dd>
</dl>
</section>
</section>
<section id="examples">
<h2>EXAMPLES<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
<section id="perl-pod">
<h3>Perl Pod<a class="headerlink" href="#perl-pod" title="Permalink to this headline">¶</a></h3>
<p>This is the definition (pod.ctags) used in ctags for parsing Pod
(<a class="reference external" href="https://perldoc.perl.org/perlpod.html">https://perldoc.perl.org/perlpod.html</a>) file.</p>
<div class="highlight-ctags notranslate"><div class="highlight"><pre><span></span><span class="kn">--langdef</span><span class="p">=</span><span class="nn">pod</span>
<span class="kd">--map-</span><span class="nn">pod</span><span class="p">=+</span>.pod
<span class="kd">--kinddef-</span><span class="nn">pod</span><span class="p">=</span><span class="ni">c</span><span class="p">,</span><span class="ni">chapter</span><span class="p">,</span><span class="sd">chapters</span>
<span class="kd">--kinddef-</span><span class="nn">pod</span><span class="p">=</span><span class="ni">s</span><span class="p">,</span><span class="ni">section</span><span class="p">,</span><span class="sd">sections</span>
<span class="kd">--kinddef-</span><span class="nn">pod</span><span class="p">=</span><span class="ni">S</span><span class="p">,</span><span class="ni">subsection</span><span class="p">,</span><span class="sd">subsections</span>
<span class="kd">--kinddef-</span><span class="nn">pod</span><span class="p">=</span><span class="ni">t</span><span class="p">,</span><span class="ni">subsubsection</span><span class="p">,</span><span class="sd">subsubsections</span>
<span class="kd">--regex-</span><span class="nn">pod</span><span class="p">=</span>/^=head1[ \t]+(.+)/\1/c/
<span class="kd">--regex-</span><span class="nn">pod</span><span class="p">=</span>/^=head2[ \t]+(.+)/\1/s/
<span class="kd">--regex-</span><span class="nn">pod</span><span class="p">=</span>/^=head3[ \t]+(.+)/\1/S/
<span class="kd">--regex-</span><span class="nn">pod</span><span class="p">=</span>/^=head4[ \t]+(.+)/\1/t/
</pre></div>
</div>
</section>
<section id="using-scope-regex-flags">
<h3>Using scope regex flags<a class="headerlink" href="#using-scope-regex-flags" title="Permalink to this headline">¶</a></h3>
<p>Let’s think about writing a parser for a very small subset of the Ruby
language.</p>
<p>input source file (<code class="docutils literal notranslate"><span class="pre">input.srb</span></code>):</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Example</span>
<span class="k">def</span> <span class="nf">methodA</span>
<span class="n">puts</span> <span class="s2">"in class_method"</span>
<span class="n">end</span>
<span class="k">def</span> <span class="nf">methodB</span>
<span class="n">puts</span> <span class="s2">"in class_method"</span>
<span class="n">end</span>
<span class="n">end</span>
</pre></div>
</div>
<p>The parser for the input should capture <code class="docutils literal notranslate"><span class="pre">Example</span></code> with <code class="docutils literal notranslate"><span class="pre">class</span></code> kind,
<code class="docutils literal notranslate"><span class="pre">methodA</span></code>, and <code class="docutils literal notranslate"><span class="pre">methodB</span></code> with <code class="docutils literal notranslate"><span class="pre">method</span></code> kind. <code class="docutils literal notranslate"><span class="pre">methodA</span></code> and <code class="docutils literal notranslate"><span class="pre">methodB</span></code>
should have <code class="docutils literal notranslate"><span class="pre">Example</span></code> as their scope. <code class="docutils literal notranslate"><span class="pre">end:</span></code> fields of each tag
should have proper values.</p>
<p>optlib file (<code class="docutils literal notranslate"><span class="pre">sub-ruby.ctags</span></code>):</p>
<div class="highlight-ctags notranslate"><div class="highlight"><pre><span></span><span class="kn">--langdef</span><span class="p">=</span><span class="nn">subRuby</span>
<span class="kd">--map-</span><span class="nn">subRuby</span><span class="p">=</span>.srb
<span class="kd">--kinddef-</span><span class="nn">subRuby</span><span class="p">=</span><span class="ni">c</span><span class="p">,</span><span class="ni">class</span><span class="p">,</span><span class="sd">classes</span>
<span class="kd">--kinddef-</span><span class="nn">subRuby</span><span class="p">=</span><span class="ni">m</span><span class="p">,</span><span class="ni">method</span><span class="p">,</span><span class="sd">methods</span>
<span class="kd">--regex-</span><span class="nn">subRuby</span><span class="p">=</span>/^class[ \t]+([a-zA-Z][a-zA-Z0-9]+)/\1/c/{scope=push}
<span class="kd">--regex-</span><span class="nn">subRuby</span><span class="p">=</span>/^end///{scope=pop}{placeholder}
<span class="kd">--regex-</span><span class="nn">subRuby</span><span class="p">=</span>/^[ \t]+def[ \t]+([a-zA-Z][a-zA-Z0-9_]+)/\1/m/{scope=push}
<span class="kd">--regex-</span><span class="nn">subRuby</span><span class="p">=</span>/^[ \t]+end///{scope=pop}{placeholder}
</pre></div>
</div>
<p>command line and output:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$ ctags --quiet --fields=+eK \
--options=./sub-ruby.ctags -o - input.srb
Example input.srb /^class Example$/;" class end:8
methodA input.srb /^ def methodA$/;" method class:Example end:4
methodB input.srb /^ def methodB$/;" method class:Example end:7
</pre></div>
</div>
</section>
</section>
<section id="see-also">
<h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline">¶</a></h2>
<p>The official Universal Ctags web site at:</p>
<p><a class="reference external" href="https://ctags.io/">https://ctags.io/</a></p>
<p><a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a>, <a class="reference internal" href="tags.5.html#tags-5"><span class="std std-ref">tags(5)</span></a>, regex(3), regex(7), egrep(1)</p>
</section>
<section id="author">
<h2>AUTHOR<a class="headerlink" href="#author" title="Permalink to this headline">¶</a></h2>
<p>Universal Ctags project
<a class="reference external" href="https://ctags.io/">https://ctags.io/</a>
(This man page partially derived from <a class="reference internal" href="ctags.1.html#ctags-1"><span class="std std-ref">ctags(1)</span></a> of
Executable-ctags)</p>
<p>Darren Hiebert <<a class="reference external" href="mailto:dhiebert%40users.sourceforge.net">dhiebert<span>@</span>users<span>.</span>sourceforge<span>.</span>net</a>>
<a class="reference external" href="http://DarrenHiebert.com/">http://DarrenHiebert.com/</a></p>
</section>
</section>
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<h3><a href="../index.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">ctags-optlib</a><ul>
<li><a class="reference internal" href="#synopsis">SYNOPSIS</a></li>
<li><a class="reference internal" href="#description">DESCRIPTION</a><ul>
<li><a class="reference internal" href="#storing-a-parser-definition-to-a-file">Storing a parser definition to a file</a></li>
<li><a class="reference internal" href="#overview-for-defining-a-parser">Overview for defining a parser</a></li>
</ul>
</li>
<li><a class="reference internal" href="#options">OPTIONS</a><ul>
<li><a class="reference internal" href="#flags-for-regex-lang-option">FLAGS FOR <code class="docutils literal notranslate"><span class="pre">--regex-<LANG></span></code> OPTION</a></li>
</ul>
</li>
<li><a class="reference internal" href="#examples">EXAMPLES</a><ul>
<li><a class="reference internal" href="#perl-pod">Perl Pod</a></li>
<li><a class="reference internal" href="#using-scope-regex-flags">Using scope regex flags</a></li>
</ul>
</li>
<li><a class="reference internal" href="#see-also">SEE ALSO</a></li>
<li><a class="reference internal" href="#author">AUTHOR</a></li>
</ul>
</li>
</ul>
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