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| author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
|---|---|---|
| committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
| commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
| tree | 2764fc62da58f2ba8da7ed341643fc359873142f /ctags/docs/internal.html | |
| download | cli-tools-windows-master.tar.gz cli-tools-windows-master.tar.bz2 cli-tools-windows-master.zip | |
Diffstat (limited to 'ctags/docs/internal.html')
| -rw-r--r-- | ctags/docs/internal.html | 854 |
1 files changed, 854 insertions, 0 deletions
diff --git a/ctags/docs/internal.html b/ctags/docs/internal.html new file mode 100644 index 0000000..6767bc7 --- /dev/null +++ b/ctags/docs/internal.html @@ -0,0 +1,854 @@ + +<!DOCTYPE html> + +<html> + <head> + <meta charset="utf-8" /> + <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" /> + + <title>Input text stream — Universal Ctags 0.3.0 documentation</title> + <link rel="stylesheet" type="text/css" href="_static/pygments.css" /> + <link rel="stylesheet" type="text/css" href="_static/classic.css" /> + + <script data-url_root="./" id="documentation_options" src="_static/documentation_options.js"></script> + <script src="_static/jquery.js"></script> + <script src="_static/underscore.js"></script> + <script src="_static/doctools.js"></script> + + <link rel="index" title="Index" href="genindex.html" /> + <link rel="search" title="Search" href="search.html" /> + <link rel="next" title="Testing ctags" href="tips.html" /> + <link rel="prev" title="Writing a parser in C" href="parser-in-c.html" /> + </head><body> + <div class="related" role="navigation" aria-label="related navigation"> + <h3>Navigation</h3> + <ul> + <li class="right" style="margin-right: 10px"> + <a href="genindex.html" title="General Index" + accesskey="I">index</a></li> + <li class="right" > + <a href="tips.html" title="Testing ctags" + accesskey="N">next</a> |</li> + <li class="right" > + <a href="parser-in-c.html" title="Writing a parser in C" + accesskey="P">previous</a> |</li> + <li class="nav-item nav-item-0"><a href="index.html">Universal Ctags 0.3.0 documentation</a> »</li> + <li class="nav-item nav-item-1"><a href="extending.html" accesskey="U">Extending ctags with a parser written in C</a> »</li> + <li class="nav-item nav-item-this"><a href="">Input text stream</a></li> + </ul> + </div> + + <div class="document"> + <div class="documentwrapper"> + <div class="bodywrapper"> + <div class="body" role="main"> + + <section id="input-text-stream"> +<span id="id1"></span><h1>Input text stream<a class="headerlink" href="#input-text-stream" title="Permalink to this headline">¶</a></h1> +<figure class="align-default"> +<a class="reference internal image-reference" href="_images/input-text-stream.svg"><img alt="_images/input-text-stream.svg" src="_images/input-text-stream.svg" /></a> +</figure> +<p>Function prototypes for handling input text stream are declared in +<code class="docutils literal notranslate"><span class="pre">main/read.h</span></code>. The file exists in Exuberant Ctags, too. However, the +names functions are changed when overhauling <code class="docutils literal notranslate"><span class="pre">--line-directive</span></code> +option. (In addition macros were converted to functions for making +data structures for the input text stream opaque.)</p> +<p>Ctags has 3 groups of functions for handling input: <em>input</em>, <em>bypass</em>, and +<em>raw</em>. Parser developers should use input group. The rest of two +are for ctags main part.</p> +<section id="inputfile-type-and-the-functions-of-input-group"> +<span id="inputfile"></span><h2><cite>inputFile</cite> type and the functions of input group<a class="headerlink" href="#inputfile-type-and-the-functions-of-input-group" title="Permalink to this headline">¶</a></h2> +<div class="admonition note"> +<p class="admonition-title">Note</p> +<p>The original version of this section was written +before <code class="docutils literal notranslate"><span class="pre">inputFile</span></code> type and <code class="docutils literal notranslate"><span class="pre">File</span></code> variable are made private.</p> +</div> +<p><code class="docutils literal notranslate"><span class="pre">inputFile</span></code> is the type for representing the input file and stream for +a parser. It was declared in <code class="docutils literal notranslate"><span class="pre">main/read.h</span></code> but now it is defined in +<code class="docutils literal notranslate"><span class="pre">main/read.c</span></code>.</p> +<p>Ctags uses a file static variable <code class="docutils literal notranslate"><span class="pre">File</span></code> having type <code class="docutils literal notranslate"><span class="pre">inputFile</span></code> for +maintaining the input file and stream. <code class="docutils literal notranslate"><span class="pre">File</span></code> is also defined in +main/read.c as <code class="docutils literal notranslate"><span class="pre">inputFile</span></code> is.</p> +<p><code class="docutils literal notranslate"><span class="pre">fp</span></code> and <code class="docutils literal notranslate"><span class="pre">line</span></code> are the essential fields of <code class="docutils literal notranslate"><span class="pre">File</span></code>. <code class="docutils literal notranslate"><span class="pre">fp</span></code> having type +well known <code class="docutils literal notranslate"><span class="pre">MIO</span></code> declared in <code class="docutils literal notranslate"><span class="pre">main/mio.h</span></code>. By calling functions of input group +(<code class="docutils literal notranslate"><span class="pre">getcFromInputFile</span></code> and <code class="docutils literal notranslate"><span class="pre">readLineFromInputFile</span></code>), a parser gets input +text from <code class="docutils literal notranslate"><span class="pre">fp</span></code>.</p> +<p>The functions of input group updates fields <code class="docutils literal notranslate"><span class="pre">input</span></code> and <code class="docutils literal notranslate"><span class="pre">source</span></code> of <code class="docutils literal notranslate"><span class="pre">File</span></code> variable. +These two fields has type <code class="docutils literal notranslate"><span class="pre">inputFileInfo</span></code>. These two fields are for mainly +tracking the name of file and the current line number. Usually ctags uses +only <code class="docutils literal notranslate"><span class="pre">input</span></code> field. <code class="docutils literal notranslate"><span class="pre">source</span></code> field is used only when <code class="docutils literal notranslate"><span class="pre">#line</span></code> directive is found +in the current input text stream.</p> +<p>A case when a tool generates the input file from another file, a tool +can record the original source file to the generated file with using +the <code class="docutils literal notranslate"><span class="pre">#line</span></code> directive. <code class="docutils literal notranslate"><span class="pre">source</span></code> field is used for tracking/recording the +information appeared on <code class="docutils literal notranslate"><span class="pre">#line</span></code> directives.</p> +<p>Regex pattern matching are also done behind calling the functions of +this group.</p> +</section> +<section id="the-functions-of-bypass-group"> +<h2>The functions of bypass group<a class="headerlink" href="#the-functions-of-bypass-group" title="Permalink to this headline">¶</a></h2> +<p>The functions of bypass group (<code class="docutils literal notranslate"><span class="pre">readLineFromBypass</span></code> and +<code class="docutils literal notranslate"><span class="pre">readLineFromBypassSlow</span></code>) are used for reading text from <code class="docutils literal notranslate"><span class="pre">fp</span></code> field of +<code class="docutils literal notranslate"><span class="pre">File</span></code> static variable without updating <code class="docutils literal notranslate"><span class="pre">input</span></code> and <code class="docutils literal notranslate"><span class="pre">source</span></code> fields of +<code class="docutils literal notranslate"><span class="pre">File</span></code> variable.</p> +<p>Parsers may not need the functions of this group. The functions are +used in ctags main part. The functions are used to make pattern +fields of tags file, for example.</p> +</section> +<section id="the-functions-of-raw-group"> +<h2>The functions of raw group<a class="headerlink" href="#the-functions-of-raw-group" title="Permalink to this headline">¶</a></h2> +<p>The functions of this group (<code class="docutils literal notranslate"><span class="pre">readLineRaw</span></code> and <code class="docutils literal notranslate"><span class="pre">readLineRawWithNoSeek</span></code>) +take a parameter having type <code class="docutils literal notranslate"><span class="pre">MIO</span></code>; and don’t touch <code class="docutils literal notranslate"><span class="pre">File</span></code> static +variable.</p> +<p>Parsers may not need the functions of this group. The functions are +used in ctags main part. The functions are used to load option files, +for example.</p> +</section> +</section> +<section id="output-tag-stream"> +<span id="id2"></span><h1>Output tag stream<a class="headerlink" href="#output-tag-stream" title="Permalink to this headline">¶</a></h1> +<figure class="align-default"> +<a class="reference internal image-reference" href="_images/output-tag-stream.svg"><img alt="_images/output-tag-stream.svg" src="_images/output-tag-stream.svg" /></a> +</figure> +<p>Ctags provides <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code> to parsers as an entry point for writing +tag information to MIO. <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code> calls <code class="docutils literal notranslate"><span class="pre">writeTagEntry</span></code> if the +parser does not set <code class="docutils literal notranslate"><span class="pre">useCork</span></code> field. <code class="docutils literal notranslate"><span class="pre">writeTagEntry</span></code> calls <code class="docutils literal notranslate"><span class="pre">writerWriteTag</span></code>. +<code class="docutils literal notranslate"><span class="pre">writerWriteTag</span></code> just calls <code class="docutils literal notranslate"><span class="pre">writeEntry</span></code> of writer backends. +<code class="docutils literal notranslate"><span class="pre">writerTable</span></code> variable holds the four backends: ctagsWriter, etagsWriter, +xrefWriter, and jsonWriter. +One of them is chosen depending on the arguments passed to ctags.</p> +<p>If <code class="docutils literal notranslate"><span class="pre">useCork</span></code> is set, the tag information goes to a queue on memory. +The queue is flushed when <code class="docutils literal notranslate"><span class="pre">useCork</span></code> in unset. See “<a class="reference internal" href="#cork-api">cork API</a>” for more +details.</p> +<section id="cork-api"> +<h2>cork API<a class="headerlink" href="#cork-api" title="Permalink to this headline">¶</a></h2> +<section id="background-and-idea"> +<h3>Background and Idea<a class="headerlink" href="#background-and-idea" title="Permalink to this headline">¶</a></h3> +<p><em>cork API</em> is introduced for recording scope information easier.</p> +<p>Before introducing cork API, a scope information must be recorded as +strings. It is flexible but memory management is required. +Following code is taken from <code class="docutils literal notranslate"><span class="pre">clojure.c</span></code> (with some modifications).</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">vStringLength</span> <span class="p">(</span><span class="n">parent</span><span class="p">)</span> <span class="o">></span> <span class="mi">0</span><span class="p">)</span> +<span class="p">{</span> + <span class="n">current</span><span class="p">.</span><span class="n">extensionFields</span><span class="p">.</span><span class="n">scope</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="n">ClojureKinds</span><span class="p">[</span><span class="n">K_NAMESPACE</span><span class="p">].</span><span class="n">name</span><span class="p">;</span> + <span class="n">current</span><span class="p">.</span><span class="n">extensionFields</span><span class="p">.</span><span class="n">scope</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="n">vStringValue</span> <span class="p">(</span><span class="n">parent</span><span class="p">);</span> +<span class="p">}</span> + +<span class="n">makeTagEntry</span> <span class="p">(</span><span class="o">&</span><span class="n">current</span><span class="p">);</span> +</pre></div> +</div> +<p><code class="docutils literal notranslate"><span class="pre">parent</span></code>, <code class="docutils literal notranslate"><span class="pre">scope</span> <span class="pre">[0]</span></code> and <code class="docutils literal notranslate"><span class="pre">scope</span> <span class="pre">[1]</span></code> are vStrings. The parser must manage +their life cycles; the parser cannot free them till the tag referring them via +its scope fields are emitted, and must free them after emitting.</p> +<p>cork API provides more solid way to hold scope information. cork API +expects <code class="docutils literal notranslate"><span class="pre">parent</span></code>, which represents scope of a tag(<code class="docutils literal notranslate"><span class="pre">current</span></code>) +currently parser dealing, is recorded to a <em>tags</em> file before recording +the <code class="docutils literal notranslate"><span class="pre">current</span></code> tag via <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code> function.</p> +<p>For passing the information about <code class="docutils literal notranslate"><span class="pre">parent</span></code> to <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code>, +<code class="docutils literal notranslate"><span class="pre">tagEntryInfo</span></code> object was created. It was used just for recording; and +freed after recording. In cork API, it is not freed after recording; +a parser can reused it as scope information.</p> +</section> +<section id="how-to-use"> +<h3>How to use<a class="headerlink" href="#how-to-use" title="Permalink to this headline">¶</a></h3> +<p>See a commit titled with “<a class="reference external" href="https://github.com/universal-ctags/ctags/commit/ef181e6">clojure: use cork</a>”. +I applied cork API to the clojure parser.</p> +<p>Cork API can be enabled and disabled per parser, +and is disabled by default. So there is no impact till you +enables it in your parser.</p> +<p><code class="docutils literal notranslate"><span class="pre">useCork</span></code> field is introduced in <code class="docutils literal notranslate"><span class="pre">parserDefinition</span></code> type:</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">typedef</span> <span class="k">struct</span> <span class="p">{</span> +<span class="p">...</span> + <span class="kt">unsigned</span> <span class="kt">int</span> <span class="n">useCork</span><span class="p">;</span> +<span class="p">...</span> +<span class="p">}</span> <span class="n">parserDefinition</span><span class="p">;</span> +</pre></div> +</div> +<p>Set <code class="docutils literal notranslate"><span class="pre">CORK_QUEUE</span></code> to <code class="docutils literal notranslate"><span class="pre">useCork</span></code> like:</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">extern</span> <span class="n">parserDefinition</span> <span class="o">*</span><span class="nf">ClojureParser</span> <span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="p">...</span> + <span class="n">parserDefinition</span> <span class="o">*</span><span class="n">def</span> <span class="o">=</span> <span class="n">parserNew</span> <span class="p">(</span><span class="s">"Clojure"</span><span class="p">);</span> + <span class="p">...</span> + <span class="n">def</span><span class="o">-></span><span class="n">useCork</span> <span class="o">=</span> <span class="n">CORK_QUEUE</span><span class="p">;</span> + <span class="k">return</span> <span class="n">def</span><span class="p">;</span> +<span class="p">}</span> +</pre></div> +</div> +<p>When ctags running a parser with <code class="docutils literal notranslate"><span class="pre">useCork</span></code> being <code class="docutils literal notranslate"><span class="pre">CORK_QUEUE</span></code>, all output +requested via <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code> function calling is stored to an internal +queue, not to <code class="docutils literal notranslate"><span class="pre">tags</span></code> file. When parsing an input file is done, the +tag information stored automatically to the queue are flushed to +<code class="docutils literal notranslate"><span class="pre">tags</span></code> file in batch.</p> +<p>When calling <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code> with a <code class="docutils literal notranslate"><span class="pre">tagEntryInfo</span></code> object (<code class="docutils literal notranslate"><span class="pre">parent</span></code>), +it returns an integer. The integer can be used as handle for referring +the object after calling.</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">int</span> <span class="n">parent</span> <span class="o">=</span> <span class="n">CORK_NIL</span><span class="p">;</span> +<span class="p">...</span> +<span class="n">parent</span> <span class="o">=</span> <span class="n">makeTagEntry</span> <span class="p">(</span><span class="o">&</span><span class="n">e</span><span class="p">);</span> +</pre></div> +</div> +<p>The handle can be used by setting to a <code class="docutils literal notranslate"><span class="pre">scopeIndex</span></code> +field of <code class="docutils literal notranslate"><span class="pre">current</span></code> tag, which is in the scope of <code class="docutils literal notranslate"><span class="pre">parent</span></code>.</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">current</span><span class="p">.</span><span class="n">extensionFields</span><span class="p">.</span><span class="n">scopeIndex</span> <span class="o">=</span> <span class="n">parent</span><span class="p">;</span> +</pre></div> +</div> +<p>When passing <code class="docutils literal notranslate"><span class="pre">current</span></code> to <code class="docutils literal notranslate"><span class="pre">makeTagEntry</span></code>, the <code class="docutils literal notranslate"><span class="pre">scopeIndex</span></code> is +referred for emitting the scope information of <code class="docutils literal notranslate"><span class="pre">current</span></code>.</p> +<p><code class="docutils literal notranslate"><span class="pre">scopeIndex</span></code> must be set to <code class="docutils literal notranslate"><span class="pre">CORK_NIL</span></code> if a tag is not in any scope. +When using <code class="docutils literal notranslate"><span class="pre">scopeIndex</span></code> of <code class="docutils literal notranslate"><span class="pre">current</span></code>, <code class="docutils literal notranslate"><span class="pre">NULL</span></code> must be assigned to both +<code class="docutils literal notranslate"><span class="pre">current.extensionFields.scope[0]</span></code> and +<code class="docutils literal notranslate"><span class="pre">current.extensionFields.scope[1]</span></code>. <code class="docutils literal notranslate"><span class="pre">initTagEntry</span></code> function does this +initialization internally, so you generally you don’t have to write +the initialization explicitly.</p> +</section> +<section id="automatic-full-qualified-tag-generation"> +<h3>Automatic full qualified tag generation<a class="headerlink" href="#automatic-full-qualified-tag-generation" title="Permalink to this headline">¶</a></h3> +<p>If a parser uses the cork API for recording and emitting scope +information, ctags can reuse it for generating <em>full qualified (FQ) +tags</em>. Set <code class="docutils literal notranslate"><span class="pre">requestAutomaticFQTag</span></code> field of <code class="docutils literal notranslate"><span class="pre">parserDefinition</span></code> to +<code class="docutils literal notranslate"><span class="pre">TRUE</span></code> then the main part of ctags emits FQ tags on behalf of the parser +if <code class="docutils literal notranslate"><span class="pre">--extras=+q</span></code> is given.</p> +<p>An example can be found in DTS parser:</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">extern</span> <span class="n">parserDefinition</span><span class="o">*</span> <span class="nf">DTSParser</span> <span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="k">static</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="k">const</span> <span class="n">extensions</span> <span class="p">[]</span> <span class="o">=</span> <span class="p">{</span> <span class="s">"dts"</span><span class="p">,</span> <span class="s">"dtsi"</span><span class="p">,</span> <span class="nb">NULL</span> <span class="p">};</span> + <span class="n">parserDefinition</span><span class="o">*</span> <span class="k">const</span> <span class="n">def</span> <span class="o">=</span> <span class="n">parserNew</span> <span class="p">(</span><span class="s">"DTS"</span><span class="p">);</span> + <span class="p">...</span> + <span class="n">def</span><span class="o">-></span><span class="n">requestAutomaticFQTag</span> <span class="o">=</span> <span class="n">TRUE</span><span class="p">;</span> + <span class="k">return</span> <span class="n">def</span><span class="p">;</span> +<span class="p">}</span> +</pre></div> +</div> +<p>Setting <code class="docutils literal notranslate"><span class="pre">requestAutomaticFQTag</span></code> to <code class="docutils literal notranslate"><span class="pre">TRUE</span></code> implies setting +<code class="docutils literal notranslate"><span class="pre">useCork</span></code> to <code class="docutils literal notranslate"><span class="pre">CORK_QUEUE</span></code>.</p> +</section> +</section> +</section> +<section id="tokeninfo-api"> +<span id="tokeninfo"></span><h1>tokenInfo API<a class="headerlink" href="#tokeninfo-api" title="Permalink to this headline">¶</a></h1> +<p>In Exuberant Ctags, a developer can write a parser anyway; only input +stream and tagEntryInfo data structure is given.</p> +<p>However, while maintaining Universal Ctags I (Masatake YAMATO) think +we should have a framework for writing parser. Of course the framework +is optional; you can still write a parser without the framework.</p> +<p>To design a framework, I have studied how @b4n (Colomban Wendling) +writes parsers. tokenInfo API is the first fruit of my study.</p> +<p>TBW</p> +</section> +<section id="multiple-parsers"> +<h1>Multiple parsers<a class="headerlink" href="#multiple-parsers" title="Permalink to this headline">¶</a></h1> +<section id="guest-parser-promise-api"> +<span id="promiseapi"></span><h2>Guest parser (promise API)<a class="headerlink" href="#guest-parser-promise-api" title="Permalink to this headline">¶</a></h2> +<p>See “<a class="reference internal" href="running-multi-parsers.html#host-guest-parsers"><span class="std std-ref">Guest parser: Applying a parser to specified areas of input file</span></a>” about the concept of guest parsers.</p> +<section id="id3"> +<h3>Background and Idea<a class="headerlink" href="#id3" title="Permalink to this headline">¶</a></h3> +<p>More than one programming languages can be used in one input text stream. +<em>promise API</em> allows a host parser running a <a class="reference internal" href="running-multi-parsers.html#host-guest-parsers"><span class="std std-ref">guest parser</span></a> in the specified area of input text stream.</p> +<p>e.g. Code written in c language (C code) is embedded +in code written in Yacc language (Yacc code). Let’s think about this +input stream.</p> +<div class="highlight-yacc notranslate"><div class="highlight"><pre><span></span>/* foo.y */ + %token + END_OF_FILE 0 + ERROR 255 + BELL 1 + + %{ + /* C language */ + int counter; + %} + %right EQUALS + %left PLUS MINUS + ... + %% + CfgFile : CfgEntryList + { InterpretConfigs($1); } + ; + + ... + %% + int + yyerror(char *s) + { + (void)fprintf(stderr,"%s: line %d of %s\n",s,lineNum, + (scanFile?scanFile:"(unknown)")); + if (scanStr) + (void)fprintf(stderr,"last scanned symbol is: %s\n",scanStr); + return 1; + } +</pre></div> +</div> +<p>In the input the area started from <code class="docutils literal notranslate"><span class="pre">%{</span></code> to <code class="docutils literal notranslate"><span class="pre">%}</span></code> and the area started from +the second <code class="docutils literal notranslate"><span class="pre">%%</span></code> to the end of file are written in C. Yacc can be called +<em>host language</em>, and C can be called <em>guest language</em>.</p> +<p>Ctags may choose the Yacc parser for the input. However, the parser +doesn’t know about C syntax. Implementing C parser in the Yacc parser +is one of approach. However, ctags has already C parser. The Yacc +parser should utilize the existing C parser. The promise API allows this.</p> +<p>See also “<a class="reference internal" href="running-multi-parsers.html#host-guest-parsers"><span class="std std-ref">Guest parser: Applying a parser to specified areas of input file</span></a>” about more concept and examples of the +guest parser.</p> +</section> +<section id="usage"> +<h3>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h3> +<p>See a commit titled with “<a class="reference external" href="https://github.com/universal-ctags/ctags/commit/757673f">Yacc: run C parser in the areas where code +is written in C</a>”. +I applied promise API to the Yacc parser.</p> +<p>The parser for host language must track and record the <code class="docutils literal notranslate"><span class="pre">start</span></code> and the +<code class="docutils literal notranslate"><span class="pre">end</span></code> of a guest language. Pairs of <code class="docutils literal notranslate"><span class="pre">line</span> <span class="pre">number</span></code> and <code class="docutils literal notranslate"><span class="pre">byte</span> <span class="pre">offset</span></code> +represents the <code class="docutils literal notranslate"><span class="pre">start</span></code> and <code class="docutils literal notranslate"><span class="pre">end</span></code>. When the <code class="docutils literal notranslate"><span class="pre">start</span></code> and <code class="docutils literal notranslate"><span class="pre">end</span></code> are +fixed, call <code class="docutils literal notranslate"><span class="pre">makePromise</span></code> with (1) the guest parser name, (2) <code class="docutils literal notranslate"><span class="pre">start</span></code>, +and (3) <code class="docutils literal notranslate"><span class="pre">end</span></code>. (This description is a bit simplified the real usage.)</p> +<p>Let’s see the actual code from “<a class="reference external" href="https://github.com/universal-ctags/ctags/blob/master/parsers/yacc.c">parsers/yacc.c</a>”.</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span> <span class="nc">cStart</span> <span class="p">{</span> + <span class="kt">unsigned</span> <span class="kt">long</span> <span class="n">input</span><span class="p">;</span> + <span class="kt">unsigned</span> <span class="kt">long</span> <span class="n">source</span><span class="p">;</span> +<span class="p">};</span> +</pre></div> +</div> +<p>Both fields are for recording <code class="docutils literal notranslate"><span class="pre">start</span></code>. <code class="docutils literal notranslate"><span class="pre">input</span></code> field +is for recording the value returned from <code class="docutils literal notranslate"><span class="pre">getInputLineNumber</span></code>. +<code class="docutils literal notranslate"><span class="pre">source</span></code> is for <code class="docutils literal notranslate"><span class="pre">getSourceLineNumber</span></code>. See “<a class="reference internal" href="#inputfile">inputFile</a>” for the +difference of the two.</p> +<p><code class="docutils literal notranslate"><span class="pre">enter_c_prologue</span></code> shown in the next is a function called when <code class="docutils literal notranslate"><span class="pre">%{</span></code> is +found in the current input text stream. Remember, in yacc syntax, <code class="docutils literal notranslate"><span class="pre">%{</span></code> +is a marker of C code area.</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">void</span> <span class="nf">enter_c_prologue</span> <span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">line</span> <span class="n">CTAGS_ATTR_UNUSED</span><span class="p">,</span> + <span class="k">const</span> <span class="n">regexMatch</span> <span class="o">*</span><span class="n">matches</span> <span class="n">CTAGS_ATTR_UNUSED</span><span class="p">,</span> + <span class="kt">unsigned</span> <span class="kt">int</span> <span class="n">count</span> <span class="n">CTAGS_ATTR_UNUSED</span><span class="p">,</span> + <span class="kt">void</span> <span class="o">*</span><span class="n">data</span><span class="p">)</span> +<span class="p">{</span> + <span class="k">struct</span> <span class="nc">cStart</span> <span class="o">*</span><span class="n">cstart</span> <span class="o">=</span> <span class="n">data</span><span class="p">;</span> + + + <span class="n">readLineFromInputFile</span> <span class="p">();</span> + <span class="n">cstart</span><span class="o">-></span><span class="n">input</span> <span class="o">=</span> <span class="n">getInputLineNumber</span> <span class="p">();</span> + <span class="n">cstart</span><span class="o">-></span><span class="n">source</span> <span class="o">=</span> <span class="n">getSourceLineNumber</span> <span class="p">();</span> +<span class="p">}</span> +</pre></div> +</div> +<p>The function just records the start line. It calls +<code class="docutils literal notranslate"><span class="pre">readLineFromInputFile</span></code> because the C code may start the next line of +the line where the marker is.</p> +<p><code class="docutils literal notranslate"><span class="pre">leave_c_prologue</span></code> shown in the next is a function called when <code class="docutils literal notranslate"><span class="pre">%}</span></code>, +the end marker of C code area, is found in the current input text stream.</p> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">void</span> <span class="nf">leave_c_prologue</span> <span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">line</span> <span class="n">CTAGS_ATTR_UNUSED</span><span class="p">,</span> + <span class="k">const</span> <span class="n">regexMatch</span> <span class="o">*</span><span class="n">matches</span> <span class="n">CTAGS_ATTR_UNUSED</span><span class="p">,</span> + <span class="kt">unsigned</span> <span class="kt">int</span> <span class="n">count</span> <span class="n">CTAGS_ATTR_UNUSED</span><span class="p">,</span> + <span class="kt">void</span> <span class="o">*</span><span class="n">data</span><span class="p">)</span> +<span class="p">{</span> + <span class="k">struct</span> <span class="nc">cStart</span> <span class="o">*</span><span class="n">cstart</span> <span class="o">=</span> <span class="n">data</span><span class="p">;</span> + <span class="kt">unsigned</span> <span class="kt">long</span> <span class="n">c_end</span><span class="p">;</span> + + <span class="n">c_end</span> <span class="o">=</span> <span class="n">getInputLineNumber</span> <span class="p">();</span> + <span class="n">makePromise</span> <span class="p">(</span><span class="s">"C"</span><span class="p">,</span> <span class="n">cstart</span><span class="o">-></span><span class="n">input</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">c_end</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="n">cstart</span><span class="o">-></span><span class="n">source</span><span class="p">);</span> +<span class="p">}</span> +</pre></div> +</div> +<p>After recording the line number of the end of the C code area, +<code class="docutils literal notranslate"><span class="pre">leave_c_prologue</span></code> calls <code class="docutils literal notranslate"><span class="pre">makePromise</span></code>.</p> +<p>Of course <code class="docutils literal notranslate"><span class="pre">"C"</span></code> stands for C language, the name of guest parser. +Available parser names can be listed by running ctags with +<code class="docutils literal notranslate"><span class="pre">--list-languages</span></code> option. In this example two <code class="docutils literal notranslate"><span class="pre">0</span></code> characters are provided as +the 3rd and 5th argument. They are byte offsets of the start and the end of the +C language area from the beginning of the line which is 0 in this case. In +general, the guest language’s section does not have to start at the beginning of +the line in which case the two offsets have to be provided. Compilers reading +the input character by character can obtain the current offset by calling +<code class="docutils literal notranslate"><span class="pre">getInputLineOffset()</span></code>.</p> +</section> +<section id="internal-design"> +<h3>Internal design<a class="headerlink" href="#internal-design" title="Permalink to this headline">¶</a></h3> +<figure class="align-default"> +<a class="reference internal image-reference" href="_images/promise.svg"><img alt="_images/promise.svg" src="_images/promise.svg" /></a> +</figure> +<p>A host parser cannot run a guest parser directly. What the host parser +can do is just asking the ctags main part scheduling of running the +guest parser for specified area which defined with the <code class="docutils literal notranslate"><span class="pre">start</span></code> and +<code class="docutils literal notranslate"><span class="pre">end</span></code>. These scheduling requests are called <em>promises</em>.</p> +<p>After running the host parser, before closing the input stream, the +ctags main part checks the existence of promise(s). If there is, the +main part makes a sub input stream and run the guest parser specified +in the promise. The sub input stream is made from the original input +stream by narrowing as requested in the promise. The main part +iterates the above process till there is no promise.</p> +<p>Theoretically a guest parser can be nested; it can make a promise. +The level 2 guest is also just scheduled. (However, I have never +tested such a nested guest parser).</p> +<p>Why not running the guest parser directly from the context of the host +parser? Remember many parsers have their own file static variables. If +a parser is called from the parser, the variables may be crashed.</p> +</section> +</section> +<section id="api-for-subparser"> +<h2>API for subparser<a class="headerlink" href="#api-for-subparser" title="Permalink to this headline">¶</a></h2> +<p>See “<a class="reference internal" href="running-multi-parsers.html#base-sub-parsers"><span class="std std-ref">Subparser: Tagging definitions of higher (upper) level language</span></a>” about the concept of subparser.</p> +<div class="admonition note"> +<p class="admonition-title">Note</p> +<p>Consider using optlib when implementing a subparser. It is much more +easy and simple. See “<a class="reference internal" href="optlib.html#defining-subparsers"><span class="std std-ref">Defining a subparser</span></a>” for details.</p> +</div> +<section id="outline"> +<h3>Outline<a class="headerlink" href="#outline" title="Permalink to this headline">¶</a></h3> +<p>You have to work on both sides: a base parser and subparsers.</p> +<p>A base parser must define a data structure type (<code class="docutils literal notranslate"><span class="pre">baseMethodTable</span></code>) for +its subparsers by extending <code class="docutils literal notranslate"><span class="pre">struct</span> <span class="pre">subparser</span></code> defined in +<code class="docutils literal notranslate"><span class="pre">main/subparser.h</span></code>. A subparser defines a variable (<code class="docutils literal notranslate"><span class="pre">subparser</span> <span class="pre">var</span></code>) +having type <code class="docutils literal notranslate"><span class="pre">baseMethodTable</span></code> by filling its fields and registers +<code class="docutils literal notranslate"><span class="pre">subparser</span> <span class="pre">var</span></code> to the base parser using dependency API.</p> +<p>The base parser calls functions pointed by <code class="docutils literal notranslate"><span class="pre">baseMethodTable</span></code> of +subparsers during parsing. A function for probing a higher level +language may be included in <code class="docutils literal notranslate"><span class="pre">baseMethodTable</span></code>. What kind of fields +should be included in <code class="docutils literal notranslate"><span class="pre">baseMethodTable</span></code> is up to the design of a base +parser and the requirements of its subparsers. A method for +probing is one of them.</p> +<p>Registering a <code class="docutils literal notranslate"><span class="pre">subparser</span> <span class="pre">var</span></code> to a base parser is enough for the +bottom up choice. For handling the top down choice (e.g. specifying +<code class="docutils literal notranslate"><span class="pre">--language-force=<subparser></span></code> in a command line), more code is needed.</p> +<p>In the top down choice, the subparser must call <code class="docutils literal notranslate"><span class="pre">scheduleRunningBasepaser</span></code>, +declared in <code class="docutils literal notranslate"><span class="pre">main/subparser.h</span></code>, in its <code class="docutils literal notranslate"><span class="pre">parser</span></code> method. +Here, <code class="docutils literal notranslate"><span class="pre">parser</span></code> method means a function assigned to the <code class="docutils literal notranslate"><span class="pre">parser</span></code> member of +the <code class="docutils literal notranslate"><span class="pre">parserDefinition</span></code> of the subparser. +<code class="docutils literal notranslate"><span class="pre">scheduleRunningBaseparser</span></code> takes an integer argument +that specifies the dependency used for registering the <code class="docutils literal notranslate"><span class="pre">subparser</span> <span class="pre">var</span></code>.</p> +<p>By extending <code class="docutils literal notranslate"><span class="pre">struct</span> <span class="pre">subparser</span></code> you can define a type for +your subparser. Then make a variable for the type and +declare a dependency on the base parser.</p> +</section> +<section id="fields-of-subparser-type"> +<h3>Fields of <code class="docutils literal notranslate"><span class="pre">subparser</span></code> type<a class="headerlink" href="#fields-of-subparser-type" title="Permalink to this headline">¶</a></h3> +<p>Here the source code of Autoconf/m4 parsers is referred as an example.</p> +<p><code class="docutils literal notranslate"><span class="pre">main/types.h</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">struct</span> <span class="nc">sSubparser</span><span class="p">;</span> +<span class="k">typedef</span> <span class="k">struct</span> <span class="nc">sSubparser</span> <span class="n">subparser</span><span class="p">;</span> +</pre></div> +</div> +<p><code class="docutils literal notranslate"><span class="pre">main/subparser.h</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">typedef</span> <span class="k">enum</span> <span class="n">eSubparserRunDirection</span> <span class="p">{</span> + <span class="n">SUBPARSER_BASE_RUNS_SUB</span> <span class="o">=</span> <span class="mi">1</span> <span class="o"><<</span> <span class="mi">0</span><span class="p">,</span> + <span class="n">SUBPARSER_SUB_RUNS_BASE</span> <span class="o">=</span> <span class="mi">1</span> <span class="o"><<</span> <span class="mi">1</span><span class="p">,</span> + <span class="n">SUBPARSER_BI_DIRECTION</span> <span class="o">=</span> <span class="n">SUBPARSER_BASE_RUNS_SUB</span><span class="o">|</span><span class="n">SUBPARSER_SUB_RUNS_BASE</span><span class="p">,</span> +<span class="p">}</span> <span class="n">subparserRunDirection</span><span class="p">;</span> + +<span class="k">struct</span> <span class="nc">sSubparser</span> <span class="p">{</span> + <span class="p">...</span> + + <span class="cm">/* public to the parser */</span> + <span class="n">subparserRunDirection</span> <span class="n">direction</span><span class="p">;</span> + + <span class="kt">void</span> <span class="p">(</span><span class="o">*</span> <span class="n">inputStart</span><span class="p">)</span> <span class="p">(</span><span class="n">subparser</span> <span class="o">*</span><span class="n">s</span><span class="p">);</span> + <span class="kt">void</span> <span class="p">(</span><span class="o">*</span> <span class="n">inputEnd</span><span class="p">)</span> <span class="p">(</span><span class="n">subparser</span> <span class="o">*</span><span class="n">s</span><span class="p">);</span> + <span class="kt">void</span> <span class="p">(</span><span class="o">*</span> <span class="n">exclusiveSubparserChosenNotify</span><span class="p">)</span> <span class="p">(</span><span class="n">subparser</span> <span class="o">*</span><span class="n">s</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">data</span><span class="p">);</span> +<span class="p">};</span> +</pre></div> +</div> +<p>A subparser must fill the fields of <code class="docutils literal notranslate"><span class="pre">subparser</span></code>.</p> +<p><code class="docutils literal notranslate"><span class="pre">direction</span></code> field specifies how the subparser is called. See +“<a class="reference internal" href="running-multi-parsers.html#multiple-parsers-directions"><span class="std std-ref">Direction flags</span></a>” in “<a class="reference internal" href="running-multi-parsers.html#multiple-parsers"><span class="std std-ref">Running multiple parsers on an input file</span></a>” about +<em>direction flags</em>, and see “<a class="reference internal" href="optlib.html#optlib-directions"><span class="std std-ref">Direction flags</span></a>” in “<a class="reference internal" href="optlib.html#optlib"><span class="std std-ref">Extending ctags with Regex parser (optlib)</span></a>” for +examples of using the direction flags.</p> +<table class="docutils align-default"> +<colgroup> +<col style="width: 55%" /> +<col style="width: 45%" /> +</colgroup> +<thead> +<tr class="row-odd"><th class="head"><p><code class="docutils literal notranslate"><span class="pre">direction</span></code> field</p></th> +<th class="head"><p>Direction Flag</p></th> +</tr> +</thead> +<tbody> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">SUBPARSER_BASE_RUNS_SUB</span></code></p></td> +<td><p><code class="docutils literal notranslate"><span class="pre">shared</span></code> (default)</p></td> +</tr> +<tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">SUBPARSER_SUB_RUNS_BASE</span></code></p></td> +<td><p><code class="docutils literal notranslate"><span class="pre">dedicated</span></code></p></td> +</tr> +<tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">SUBPARSER_BI_DIRECTION</span></code></p></td> +<td><p><code class="docutils literal notranslate"><span class="pre">bidirectional</span></code></p></td> +</tr> +</tbody> +</table> +<p>If a subparser runs exclusively and is chosen in top down way, set +<code class="docutils literal notranslate"><span class="pre">SUBPARSER_SUB_RUNS_BASE</span></code> flag. If a subparser runs coexisting way and +is chosen in bottom up way, set <code class="docutils literal notranslate"><span class="pre">SUBPARSER_BASE_RUNS_SUB</span></code>. Use +<code class="docutils literal notranslate"><span class="pre">SUBPARSER_BI_DIRECTION</span></code> if both cases can be considered.</p> +<p>SystemdUnit parser runs as a subparser of iniconf base parser. +SystemdUnit parser specifies <code class="docutils literal notranslate"><span class="pre">SUBPARSER_SUB_RUNS_BASE</span></code> because +unit files of systemd have very specific file extensions though +they are written in iniconf syntax. Therefore we expect SystemdUnit +parser is chosen in top down way. The same logic is applicable to +YumRepo parser.</p> +<p>Autoconf parser specifies <code class="docutils literal notranslate"><span class="pre">SUBPARSER_BI_DIRECTION</span></code>. For input +file having name <code class="docutils literal notranslate"><span class="pre">configure.ac</span></code>, by pattern matching, Autoconf parser +is chosen in top down way. In other hand, for file name <code class="docutils literal notranslate"><span class="pre">foo.m4</span></code>, +Autoconf parser can be chosen in bottom up way.</p> +<p><code class="docutils literal notranslate"><span class="pre">inputStart</span></code> is called before the base parser starting parsing a new input file. +<code class="docutils literal notranslate"><span class="pre">inputEnd</span></code> is called after the base parser finishing parsing the input file. +Universal Ctags main part calls these methods. Therefore, a base parser doesn’t +have to call them.</p> +<p><code class="docutils literal notranslate"><span class="pre">exclusiveSubparserChosenNotify</span></code> is called when a parser is chosen +as an exclusive parser. Calling this method is a job of a base parser.</p> +</section> +<section id="extending-subparser-type"> +<h3>Extending <code class="docutils literal notranslate"><span class="pre">subparser</span></code> type<a class="headerlink" href="#extending-subparser-type" title="Permalink to this headline">¶</a></h3> +<p>The m4 parser extends <code class="docutils literal notranslate"><span class="pre">subparser</span></code> type like following:</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/m4.h</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">typedef</span> <span class="k">struct</span> <span class="nc">sM4Subparser</span> <span class="n">m4Subparser</span><span class="p">;</span> +<span class="k">struct</span> <span class="nc">sM4Subparser</span> <span class="p">{</span> + <span class="n">subparser</span> <span class="n">subparser</span><span class="p">;</span> + + <span class="kt">bool</span> <span class="p">(</span><span class="o">*</span> <span class="n">probeLanguage</span><span class="p">)</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span><span class="o">*</span> <span class="n">token</span><span class="p">);</span> + + <span class="cm">/* return value: Cork index */</span> + <span class="kt">int</span> <span class="p">(</span><span class="o">*</span> <span class="n">newMacroNotify</span><span class="p">)</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span><span class="o">*</span> <span class="n">token</span><span class="p">);</span> + + <span class="kt">bool</span> <span class="p">(</span><span class="o">*</span> <span class="n">doesLineCommentStart</span><span class="p">)</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4</span><span class="p">,</span> <span class="kt">int</span> <span class="n">c</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">token</span><span class="p">);</span> + <span class="kt">bool</span> <span class="p">(</span><span class="o">*</span> <span class="n">doesStringLiteralStart</span><span class="p">)</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4</span><span class="p">,</span> <span class="kt">int</span> <span class="n">c</span><span class="p">);</span> +<span class="p">};</span> +</pre></div> +</div> +<p>Put <code class="docutils literal notranslate"><span class="pre">subparser</span></code> as the first member of the extended struct (here sM4Subparser). +In addition the first field, 4 methods are defined in the extended struct.</p> +<p>Till choosing a subparser for the current input file, the m4 parser calls +<code class="docutils literal notranslate"><span class="pre">probeLanguage</span></code> method of its subparsers each time when find a token +in the input file. A subparser returns <code class="docutils literal notranslate"><span class="pre">true</span></code> if it recognizes the +input file is for the itself by analyzing tokens passed from the +base parser.</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/autoconf.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">extern</span> <span class="n">parserDefinition</span><span class="o">*</span> <span class="nf">AutoconfParser</span> <span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="k">static</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="k">const</span> <span class="n">patterns</span> <span class="p">[]</span> <span class="o">=</span> <span class="p">{</span> <span class="s">"configure.in"</span><span class="p">,</span> <span class="nb">NULL</span> <span class="p">};</span> + <span class="k">static</span> <span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="k">const</span> <span class="n">extensions</span> <span class="p">[]</span> <span class="o">=</span> <span class="p">{</span> <span class="s">"ac"</span><span class="p">,</span> <span class="nb">NULL</span> <span class="p">};</span> + <span class="n">parserDefinition</span><span class="o">*</span> <span class="k">const</span> <span class="n">def</span> <span class="o">=</span> <span class="n">parserNew</span><span class="p">(</span><span class="s">"Autoconf"</span><span class="p">);</span> + + <span class="k">static</span> <span class="n">m4Subparser</span> <span class="n">autoconfSubparser</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">.</span><span class="n">subparser</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">.</span><span class="n">direction</span> <span class="o">=</span> <span class="n">SUBPARSER_BI_DIRECTION</span><span class="p">,</span> + <span class="p">.</span><span class="n">exclusiveSubparserChosenNotify</span> <span class="o">=</span> <span class="n">exclusiveSubparserChosenCallback</span><span class="p">,</span> + <span class="p">},</span> + <span class="p">.</span><span class="n">probeLanguage</span> <span class="o">=</span> <span class="n">probeLanguage</span><span class="p">,</span> + <span class="p">.</span><span class="n">newMacroNotify</span> <span class="o">=</span> <span class="n">newMacroCallback</span><span class="p">,</span> + <span class="p">.</span><span class="n">doesLineCommentStart</span> <span class="o">=</span> <span class="n">doesLineCommentStart</span><span class="p">,</span> + <span class="p">.</span><span class="n">doesStringLiteralStart</span> <span class="o">=</span> <span class="n">doesStringLiteralStart</span><span class="p">,</span> + <span class="p">};</span> +</pre></div> +</div> +<p><code class="docutils literal notranslate"><span class="pre">probeLanguage</span></code> function defined in <code class="docutils literal notranslate"><span class="pre">autoconf.c</span></code> is connected to +the <code class="docutils literal notranslate"><span class="pre">probeLanguage</span></code> member of <code class="docutils literal notranslate"><span class="pre">autoconfSubparser</span></code>. The <code class="docutils literal notranslate"><span class="pre">probeLanguage</span></code> function +of Autoconf is very simple:</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/autoconf.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">bool</span> <span class="nf">probeLanguage</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span><span class="o">*</span> <span class="n">token</span><span class="p">)</span> +<span class="p">{</span> + <span class="k">return</span> <span class="n">strncmp</span> <span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="s">"m4_"</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> + <span class="o">||</span> <span class="n">strncmp</span> <span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="s">"AC_"</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> + <span class="o">||</span> <span class="n">strncmp</span> <span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="s">"AM_"</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> + <span class="o">||</span> <span class="n">strncmp</span> <span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="s">"AS_"</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> + <span class="o">||</span> <span class="n">strncmp</span> <span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="s">"AH_"</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span> + <span class="p">;</span> +<span class="p">}</span> +</pre></div> +</div> +<p>This function checks the prefix of passed tokens. If known +prefix is found, Autoconf assumes this is an Autoconf input +and returns <code class="docutils literal notranslate"><span class="pre">true</span></code>.</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/m4.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">m4tmp</span><span class="o">-></span><span class="n">probeLanguage</span> + <span class="o">&&</span> <span class="n">m4tmp</span><span class="o">-></span><span class="n">probeLanguage</span> <span class="p">(</span><span class="n">m4tmp</span><span class="p">,</span> <span class="n">token</span><span class="p">))</span> +<span class="p">{</span> + <span class="n">chooseExclusiveSubparser</span> <span class="p">((</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="p">)</span><span class="n">tmp</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">);</span> + <span class="n">m4found</span> <span class="o">=</span> <span class="n">m4tmp</span><span class="p">;</span> +<span class="p">}</span> +</pre></div> +</div> +<p>The m4 parsers calls <code class="docutils literal notranslate"><span class="pre">probeLanguage</span></code> function of a subparser. If <code class="docutils literal notranslate"><span class="pre">true</span></code> +is returned <code class="docutils literal notranslate"><span class="pre">chooseExclusiveSubparser</span></code> function which is defined +in the main part. <code class="docutils literal notranslate"><span class="pre">chooseExclusiveSubparser</span></code> calls +<code class="docutils literal notranslate"><span class="pre">exclusiveSubparserChosenNotify</span></code> method of the chosen subparser.</p> +<p>The method is implemented in Autoconf subparser like following:</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/autoconf.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">void</span> <span class="nf">exclusiveSubparserChosenCallback</span> <span class="p">(</span><span class="n">subparser</span> <span class="o">*</span><span class="n">s</span><span class="p">,</span> <span class="kt">void</span> <span class="o">*</span><span class="n">data</span><span class="p">)</span> +<span class="p">{</span> + <span class="n">setM4Quotes</span> <span class="p">(</span><span class="sc">'['</span><span class="p">,</span> <span class="sc">']'</span><span class="p">);</span> +<span class="p">}</span> +</pre></div> +</div> +<p>It changes quote characters of the m4 parser.</p> +</section> +<section id="making-a-tag-in-a-subparser"> +<h3>Making a tag in a subparser<a class="headerlink" href="#making-a-tag-in-a-subparser" title="Permalink to this headline">¶</a></h3> +<p>Via calling callback functions defined in subparsers, their base parser +gives chance to them making tag entries.</p> +<p>The m4 parser calls <code class="docutils literal notranslate"><span class="pre">newMacroNotify</span></code> method when it finds an m4 macro is used. +The Autoconf parser connects <code class="docutils literal notranslate"><span class="pre">newMacroCallback</span></code> function defined in <code class="docutils literal notranslate"><span class="pre">parser/autoconf.c</span></code>.</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/autoconf.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">int</span> <span class="nf">newMacroCallback</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4</span><span class="p">,</span> <span class="k">const</span> <span class="kt">char</span><span class="o">*</span> <span class="n">token</span><span class="p">)</span> +<span class="p">{</span> + <span class="kt">int</span> <span class="n">keyword</span><span class="p">;</span> + <span class="kt">int</span> <span class="n">index</span> <span class="o">=</span> <span class="n">CORK_NIL</span><span class="p">;</span> + + <span class="n">keyword</span> <span class="o">=</span> <span class="n">lookupKeyword</span> <span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="n">getInputLanguage</span> <span class="p">());</span> + + <span class="cm">/* TODO:</span> +<span class="cm"> AH_VERBATIM</span> +<span class="cm"> */</span> + <span class="k">switch</span> <span class="p">(</span><span class="n">keyword</span><span class="p">)</span> + <span class="p">{</span> + <span class="k">case</span> <span class="nl">KEYWORD_NONE</span><span class="p">:</span> + <span class="k">break</span><span class="p">;</span> + <span class="k">case</span> <span class="nl">KEYWORD_init</span><span class="p">:</span> + <span class="n">index</span> <span class="o">=</span> <span class="n">makeAutoconfTag</span> <span class="p">(</span><span class="n">PACKAGE_KIND</span><span class="p">);</span> + <span class="k">break</span><span class="p">;</span> + +<span class="p">...</span> + +<span class="k">extern</span> <span class="n">parserDefinition</span><span class="o">*</span> <span class="n">AutoconfParser</span> <span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="p">...</span> + <span class="k">static</span> <span class="n">m4Subparser</span> <span class="n">autoconfSubparser</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">.</span><span class="n">subparser</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">.</span><span class="n">direction</span> <span class="o">=</span> <span class="n">SUBPARSER_BI_DIRECTION</span><span class="p">,</span> + <span class="p">.</span><span class="n">exclusiveSubparserChosenNotify</span> <span class="o">=</span> <span class="n">exclusiveSubparserChosenCallback</span><span class="p">,</span> + <span class="p">},</span> + <span class="p">.</span><span class="n">probeLanguage</span> <span class="o">=</span> <span class="n">probeLanguage</span><span class="p">,</span> + <span class="p">.</span><span class="n">newMacroNotify</span> <span class="o">=</span> <span class="n">newMacroCallback</span><span class="p">,</span> +</pre></div> +</div> +<p>In <code class="docutils literal notranslate"><span class="pre">newMacroCallback</span></code> function, the Autoconf parser receives the name of macro +found by the base parser and analysis whether the macro is interesting +in the context of Autoconf language or not. If it is interesting name, +the Autoconf parser makes a tag for it.</p> +</section> +<section id="calling-methods-of-subparsers-from-a-base-parser"> +<h3>Calling methods of subparsers from a base parser<a class="headerlink" href="#calling-methods-of-subparsers-from-a-base-parser" title="Permalink to this headline">¶</a></h3> +<p>A base parser can use <code class="docutils literal notranslate"><span class="pre">foreachSubparser</span></code> macro for accessing its +subparsers. A base should call <code class="docutils literal notranslate"><span class="pre">enterSubparser</span></code> before calling a +method of a subparser, and call <code class="docutils literal notranslate"><span class="pre">leaveSubparser</span></code> after calling the +method. The macro and functions are declare in <code class="docutils literal notranslate"><span class="pre">main/subparser.h</span></code> .</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/m4.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="n">m4Subparser</span> <span class="o">*</span> <span class="nf">maySwitchLanguage</span> <span class="p">(</span><span class="k">const</span> <span class="kt">char</span><span class="o">*</span> <span class="n">token</span><span class="p">)</span> +<span class="p">{</span> + <span class="n">subparser</span> <span class="o">*</span><span class="n">tmp</span><span class="p">;</span> + <span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4found</span> <span class="o">=</span> <span class="nb">NULL</span><span class="p">;</span> + + <span class="n">foreachSubparser</span> <span class="p">(</span><span class="n">tmp</span><span class="p">,</span> <span class="nb">false</span><span class="p">)</span> + <span class="p">{</span> + <span class="n">m4Subparser</span> <span class="o">*</span><span class="n">m4tmp</span> <span class="o">=</span> <span class="p">(</span><span class="n">m4Subparser</span> <span class="o">*</span><span class="p">)</span><span class="n">tmp</span><span class="p">;</span> + + <span class="n">enterSubparser</span><span class="p">(</span><span class="n">tmp</span><span class="p">);</span> + <span class="k">if</span> <span class="p">(</span><span class="n">m4tmp</span><span class="o">-></span><span class="n">probeLanguage</span> + <span class="o">&&</span> <span class="n">m4tmp</span><span class="o">-></span><span class="n">probeLanguage</span> <span class="p">(</span><span class="n">m4tmp</span><span class="p">,</span> <span class="n">token</span><span class="p">))</span> + <span class="p">{</span> + <span class="n">chooseExclusiveSubparser</span> <span class="p">(</span><span class="n">tmp</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">);</span> + <span class="n">m4found</span> <span class="o">=</span> <span class="n">m4tmp</span><span class="p">;</span> + <span class="p">}</span> + <span class="n">leaveSubparser</span><span class="p">();</span> + + <span class="k">if</span> <span class="p">(</span><span class="n">m4found</span><span class="p">)</span> + <span class="k">break</span><span class="p">;</span> + <span class="p">}</span> + + <span class="k">return</span> <span class="n">m4found</span><span class="p">;</span> +<span class="p">}</span> +</pre></div> +</div> +<p><code class="docutils literal notranslate"><span class="pre">foreachSubparser</span></code> takes a variable having type <code class="docutils literal notranslate"><span class="pre">subparser</span></code>. +For each iteration, the value for the variable is updated.</p> +<p><code class="docutils literal notranslate"><span class="pre">enterSubparser</span></code> takes a variable having type <code class="docutils literal notranslate"><span class="pre">subparser</span></code>. With the +calling <code class="docutils literal notranslate"><span class="pre">enterSubparser</span></code>, the current language (the value returned from +<code class="docutils literal notranslate"><span class="pre">getInputLanguage</span></code>) can be temporary switched to the language specified +with the variable. One of the effect of switching is that <code class="docutils literal notranslate"><span class="pre">language</span></code> +field of tags made in the callback function called between +<code class="docutils literal notranslate"><span class="pre">enterSubparser</span></code> and <code class="docutils literal notranslate"><span class="pre">leaveSubparser</span></code> is adjusted.</p> +</section> +<section id="registering-a-subparser-to-its-base-parser"> +<h3>Registering a subparser to its base parser<a class="headerlink" href="#registering-a-subparser-to-its-base-parser" title="Permalink to this headline">¶</a></h3> +<p>Use <code class="docutils literal notranslate"><span class="pre">DEPTYPE_SUBPARSER</span></code> dependency in a subparser for registration.</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/autoconf.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">extern</span> <span class="n">parserDefinition</span><span class="o">*</span> <span class="nf">AutoconfParser</span> <span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="n">parserDefinition</span><span class="o">*</span> <span class="k">const</span> <span class="n">def</span> <span class="o">=</span> <span class="n">parserNew</span><span class="p">(</span><span class="s">"Autoconf"</span><span class="p">);</span> + + <span class="k">static</span> <span class="n">m4Subparser</span> <span class="n">autoconfSubparser</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">.</span><span class="n">subparser</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">.</span><span class="n">direction</span> <span class="o">=</span> <span class="n">SUBPARSER_BI_DIRECTION</span><span class="p">,</span> + <span class="p">.</span><span class="n">exclusiveSubparserChosenNotify</span> <span class="o">=</span> <span class="n">exclusiveSubparserChosenCallback</span><span class="p">,</span> + <span class="p">},</span> + <span class="p">.</span><span class="n">probeLanguage</span> <span class="o">=</span> <span class="n">probeLanguage</span><span class="p">,</span> + <span class="p">.</span><span class="n">newMacroNotify</span> <span class="o">=</span> <span class="n">newMacroCallback</span><span class="p">,</span> + <span class="p">.</span><span class="n">doesLineCommentStart</span> <span class="o">=</span> <span class="n">doesLineCommentStart</span><span class="p">,</span> + <span class="p">.</span><span class="n">doesStringLiteralStart</span> <span class="o">=</span> <span class="n">doesStringLiteralStart</span><span class="p">,</span> + <span class="p">};</span> + <span class="k">static</span> <span class="n">parserDependency</span> <span class="n">dependencies</span> <span class="p">[]</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="p">{</span> <span class="n">DEPTYPE_SUBPARSER</span><span class="p">,</span> <span class="s">"M4"</span><span class="p">,</span> <span class="o">&</span><span class="n">autoconfSubparser</span> <span class="p">},</span> + <span class="p">};</span> + + <span class="n">def</span><span class="o">-></span><span class="n">dependencies</span> <span class="o">=</span> <span class="n">dependencies</span><span class="p">;</span> + <span class="n">def</span><span class="o">-></span><span class="n">dependencyCount</span> <span class="o">=</span> <span class="n">ARRAY_SIZE</span> <span class="p">(</span><span class="n">dependencies</span><span class="p">);</span> +</pre></div> +</div> +<p><code class="docutils literal notranslate"><span class="pre">DEPTYPE_SUBPARSER</span></code> is specified in the 0th element of <code class="docutils literal notranslate"><span class="pre">dependencies</span></code> +function static variable. In the next a literal string “M4” is +specified and <code class="docutils literal notranslate"><span class="pre">autoconfSubparser</span></code> follows. The intent of the code is +registering <code class="docutils literal notranslate"><span class="pre">autoconfSubparser</span></code> subparser definition to a base parser +named “M4”.</p> +<p><code class="docutils literal notranslate"><span class="pre">dependencies</span></code> function static variable must be assigned to +<code class="docutils literal notranslate"><span class="pre">dependencies</span></code> fields of a variable of <code class="docutils literal notranslate"><span class="pre">parserDefinition</span></code>. +The main part of Universal Ctags refers the field when +initializing parsers.</p> +<p><code class="docutils literal notranslate"><span class="pre">[0]</span></code> emphasizes this is “the 0th element”. The subparser may refer +the index of the array when the subparser calls +<code class="docutils literal notranslate"><span class="pre">scheduleRunningBaseparser</span></code>.</p> +</section> +<section id="scheduling-running-the-base-parser"> +<h3>Scheduling running the base parser<a class="headerlink" href="#scheduling-running-the-base-parser" title="Permalink to this headline">¶</a></h3> +<p>For the case that a subparser is chosen in top down, the subparser +must call <code class="docutils literal notranslate"><span class="pre">scheduleRunningBaseparser</span></code> in the main <code class="docutils literal notranslate"><span class="pre">parser</span></code> method.</p> +<p><code class="docutils literal notranslate"><span class="pre">parsers/autoconf.c</span></code>:</p> +<div class="highlight-C notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="kt">void</span> <span class="nf">findAutoconfTags</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="n">scheduleRunningBaseparser</span> <span class="p">(</span><span class="mi">0</span><span class="p">);</span> +<span class="p">}</span> + +<span class="k">extern</span> <span class="n">parserDefinition</span><span class="o">*</span> <span class="nf">AutoconfParser</span> <span class="p">(</span><span class="kt">void</span><span class="p">)</span> +<span class="p">{</span> + <span class="p">...</span> + <span class="n">parserDefinition</span><span class="o">*</span> <span class="k">const</span> <span class="n">def</span> <span class="o">=</span> <span class="n">parserNew</span><span class="p">(</span><span class="s">"Autoconf"</span><span class="p">);</span> + <span class="p">...</span> + <span class="k">static</span> <span class="n">parserDependency</span> <span class="n">dependencies</span> <span class="p">[]</span> <span class="o">=</span> <span class="p">{</span> + <span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="o">=</span> <span class="p">{</span> <span class="n">DEPTYPE_SUBPARSER</span><span class="p">,</span> <span class="s">"M4"</span><span class="p">,</span> <span class="o">&</span><span class="n">autoconfSubparser</span> <span class="p">},</span> + <span class="p">};</span> + + <span class="n">def</span><span class="o">-></span><span class="n">dependencies</span> <span class="o">=</span> <span class="n">dependencies</span><span class="p">;</span> + <span class="p">...</span> + <span class="n">def</span><span class="o">-></span><span class="n">parser</span> <span class="o">=</span> <span class="n">findAutoconfTags</span><span class="p">;</span> + <span class="p">...</span> + <span class="k">return</span> <span class="n">def</span><span class="p">;</span> +<span class="p">}</span> +</pre></div> +</div> +<p>A subparser can do nothing actively. A base parser makes its subparser +work by calling methods of the subparser. Therefore a subparser must +run its base parser when the subparser is chosen in a top down way, +The main part prepares <code class="docutils literal notranslate"><span class="pre">scheduleRunningBaseparser</span></code> function for the purpose.</p> +<p>A subparser should call the function from <code class="docutils literal notranslate"><span class="pre">parser</span></code> method of <code class="docutils literal notranslate"><span class="pre">parserDefinition</span></code> +of the subparser. <code class="docutils literal notranslate"><span class="pre">scheduleRunningBaseparser</span></code> takes an integer. It specifies +an index of the dependency which is used for registering the subparser.</p> +</section> +</section> +</section> +<section id="packcc-compiler-compiler"> +<h1>PackCC compiler-compiler<a class="headerlink" href="#packcc-compiler-compiler" title="Permalink to this headline">¶</a></h1> +<p>PackCC is a compiler-compiler; it translates <code class="docutils literal notranslate"><span class="pre">.peg</span></code> grammar file to <code class="docutils literal notranslate"><span class="pre">.c</span></code> +file. PackCC was originally written by Arihiro Yoshida. Its source +repository is at <a class="reference external" href="https://github.com/arithy/packcc">https://github.com/arithy/packcc</a>.</p> +<p>The source tree of PackCC is grafted at <code class="docutils literal notranslate"><span class="pre">misc/packcc</span></code> directory. +Building PackCC and ctags are integrated in the build-scripts of +Universal Ctags.</p> +<p>Refer <a class="reference external" href="https://github.com/universal-ctags/ctags/blob/master/peg/varlink.peg">peg/valink.peg</a> as a +sample of a parser using PackCC.</p> +</section> +<section id="automatic-parser-guessing-tbw"> +<h1>Automatic parser guessing (TBW)<a class="headerlink" href="#automatic-parser-guessing-tbw" title="Permalink to this headline">¶</a></h1> +</section> +<section id="managing-regular-expression-parsers-tbw"> +<h1>Managing regular expression parsers (TBW)<a class="headerlink" href="#managing-regular-expression-parsers-tbw" title="Permalink to this headline">¶</a></h1> +</section> +<section id="ghost-kind-in-regex-parser-tbw"> +<h1>Ghost kind in regex parser (TBW)<a class="headerlink" href="#ghost-kind-in-regex-parser-tbw" title="Permalink to this headline">¶</a></h1> +</section> + + + <div class="clearer"></div> + </div> + </div> + </div> + <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> + <div class="sphinxsidebarwrapper"> + <h3><a href="index.html">Table of Contents</a></h3> + <ul> +<li><a class="reference internal" href="#">Input text stream</a><ul> +<li><a class="reference internal" href="#inputfile-type-and-the-functions-of-input-group"><cite>inputFile</cite> type and the functions of input group</a></li> +<li><a class="reference internal" href="#the-functions-of-bypass-group">The functions of bypass group</a></li> +<li><a class="reference internal" href="#the-functions-of-raw-group">The functions of raw group</a></li> +</ul> +</li> +<li><a class="reference internal" href="#output-tag-stream">Output tag stream</a><ul> +<li><a class="reference internal" href="#cork-api">cork API</a><ul> +<li><a class="reference internal" href="#background-and-idea">Background and Idea</a></li> +<li><a class="reference internal" href="#how-to-use">How to use</a></li> +<li><a class="reference internal" href="#automatic-full-qualified-tag-generation">Automatic full qualified tag generation</a></li> +</ul> +</li> +</ul> +</li> +<li><a class="reference internal" href="#tokeninfo-api">tokenInfo API</a></li> +<li><a class="reference internal" href="#multiple-parsers">Multiple parsers</a><ul> +<li><a class="reference internal" href="#guest-parser-promise-api">Guest parser (promise API)</a><ul> +<li><a class="reference internal" href="#id3">Background and Idea</a></li> +<li><a class="reference internal" href="#usage">Usage</a></li> +<li><a class="reference internal" href="#internal-design">Internal design</a></li> +</ul> +</li> +<li><a class="reference internal" href="#api-for-subparser">API for subparser</a><ul> +<li><a class="reference internal" href="#outline">Outline</a></li> +<li><a class="reference internal" href="#fields-of-subparser-type">Fields of <code class="docutils literal notranslate"><span class="pre">subparser</span></code> type</a></li> +<li><a class="reference internal" href="#extending-subparser-type">Extending <code class="docutils literal notranslate"><span class="pre">subparser</span></code> type</a></li> +<li><a class="reference internal" href="#making-a-tag-in-a-subparser">Making a tag in a subparser</a></li> +<li><a class="reference internal" href="#calling-methods-of-subparsers-from-a-base-parser">Calling methods of subparsers from a base parser</a></li> +<li><a class="reference internal" href="#registering-a-subparser-to-its-base-parser">Registering a subparser to its base parser</a></li> +<li><a class="reference internal" href="#scheduling-running-the-base-parser">Scheduling running the base parser</a></li> +</ul> +</li> +</ul> +</li> +<li><a class="reference internal" href="#packcc-compiler-compiler">PackCC compiler-compiler</a></li> +<li><a class="reference internal" href="#automatic-parser-guessing-tbw">Automatic parser guessing (TBW)</a></li> +<li><a class="reference internal" href="#managing-regular-expression-parsers-tbw">Managing regular expression parsers (TBW)</a></li> +<li><a class="reference internal" href="#ghost-kind-in-regex-parser-tbw">Ghost kind in regex parser (TBW)</a></li> +</ul> + + <h4>Previous topic</h4> + <p class="topless"><a href="parser-in-c.html" + title="previous chapter">Writing a parser in C</a></p> + <h4>Next topic</h4> + <p class="topless"><a href="tips.html" + title="next chapter">Testing ctags</a></p> +<div id="searchbox" style="display: none" role="search"> + <h3 id="searchlabel">Quick search</h3> + <div class="searchformwrapper"> + <form class="search" action="search.html" method="get"> + <input type="text" name="q" aria-labelledby="searchlabel" /> + <input type="submit" value="Go" /> + </form> + </div> +</div> 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