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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Write your own filter — Pygments 2.2.0 documentation</title> <link rel="stylesheet" href="../_static/pygments14.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="shortcut icon" href="../_static/favicon.ico"/> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="next" title="Register Plugins" href="plugins.html" /> <link rel="prev" title="Write your own formatter" href="formatterdevelopment.html" /> <link href='http://fonts.googleapis.com/css?family=PT+Sans:300,400,700' rel='stylesheet' type='text/css'> <style type="text/css"> table.right { float: right; margin-left: 20px; } table.right td { border: 1px solid #ccc; } </style> <script type="text/javascript"> // intelligent scrolling of the sidebar content $(window).scroll(function() { var sb = $('.sphinxsidebarwrapper'); var win = $(window); var sbh = sb.height(); var offset = $('.sphinxsidebar').position()['top']; var wintop = win.scrollTop(); var winbot = wintop + win.innerHeight(); var curtop = sb.position()['top']; var curbot = curtop + sbh; // does sidebar fit in window? if (sbh < win.innerHeight()) { // yes: easy case -- always keep at the top sb.css('top', $u.min([$u.max([0, wintop - offset - 10]), $(document).height() - sbh - 200])); } else { // no: only scroll if top/bottom edge of sidebar is at // top/bottom edge of window if (curtop > wintop && curbot > winbot) { sb.css('top', $u.max([wintop - offset - 10, 0])); } else if (curtop < wintop && curbot < winbot) { sb.css('top', $u.min([winbot - sbh - offset - 20, $(document).height() - sbh - 200])); } } }); </script> </head><body> <div class="outerwrapper"> <div class="pageheader"> <ul> <li><a href="../index.html">Home</a></li> <li><a href="../languages.html">Languages</a></li> <li><a href="../faq.html">FAQ</a></li> <li><a href="../download.html">Get it</a></li> <li><a href="index.html">Docs</a></li> </ul> <div> <a href="../index.html"> <img src="../_static/logo.png" alt="Pygments logo" /> </a> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../index.html">Table Of Contents</a></h3> <ul> <li><a class="reference internal" href="#">Write your own filter</a><ul> <li><a class="reference internal" href="#subclassing-filters">Subclassing Filters</a></li> <li><a class="reference internal" href="#using-a-decorator">Using a decorator</a></li> </ul> </li> </ul> <strong>« <a href="index.html">Back to docs index</a></strong> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <div class="searchformwrapper"> <form class="search" action="../search.html" method="get"> <input type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="write-your-own-filter"> <h1>Write your own filter<a class="headerlink" href="#write-your-own-filter" title="Permalink to this headline">¶</a></h1> <div class="versionadded"> <p><span class="versionmodified">New in version 0.7.</span></p> </div> <p>Writing own filters is very easy. All you have to do is to subclass the <cite>Filter</cite> class and override the <cite>filter</cite> method. Additionally a filter is instantiated with some keyword arguments you can use to adjust the behavior of your filter.</p> <div class="section" id="subclassing-filters"> <h2>Subclassing Filters<a class="headerlink" href="#subclassing-filters" title="Permalink to this headline">¶</a></h2> <p>As an example, we write a filter that converts all <cite>Name.Function</cite> tokens to normal <cite>Name</cite> tokens to make the output less colorful.</p> <div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">pygments.util</span> <span class="kn">import</span> <span class="n">get_bool_opt</span> <span class="kn">from</span> <span class="nn">pygments.token</span> <span class="kn">import</span> <span class="n">Name</span> <span class="kn">from</span> <span class="nn">pygments.filter</span> <span class="kn">import</span> <span class="n">Filter</span> <span class="k">class</span> <span class="nc">UncolorFilter</span><span class="p">(</span><span class="n">Filter</span><span class="p">):</span> <span class="k">def</span> <span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o"></span><span class="n">options</span><span class="p">):</span> <span class="n">Filter</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o"></span><span class="n">options</span><span class="p">)</span> <span class="bp">self</span><span class="o">.</span><span class="n">class_too</span> <span class="o">=</span> <span class="n">get_bool_opt</span><span class="p">(</span><span class="n">options</span><span class="p">,</span> <span class="s1">'classtoo'</span><span class="p">)</span> <span class="k">def</span> <span class="nf">filter</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lexer</span><span class="p">,</span> <span class="n">stream</span><span class="p">):</span> <span class="k">for</span> <span class="n">ttype</span><span class="p">,</span> <span class="n">value</span> <span class="ow">in</span> <span class="n">stream</span><span class="p">:</span> <span class="k">if</span> <span class="n">ttype</span> <span class="ow">is</span> <span class="n">Name</span><span class="o">.</span><span class="n">Function</span> <span class="ow">or</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">class_too</span> <span class="ow">and</span> <span class="n">ttype</span> <span class="ow">is</span> <span class="n">Name</span><span class="o">.</span><span class="n">Class</span><span class="p">):</span> <span class="n">ttype</span> <span class="o">=</span> <span class="n">Name</span> <span class="k">yield</span> <span class="n">ttype</span><span class="p">,</span> <span class="n">value</span> </pre></div> </div> <p>Some notes on the <cite>lexer</cite> argument: that can be quite confusing since it doesn’t need to be a lexer instance. If a filter was added by using the <cite>add_filter()</cite> function of lexers, that lexer is registered for the filter. In that case <cite>lexer</cite> will refer to the lexer that has registered the filter. It <em>can</em> be used to access options passed to a lexer. Because it could be <cite>None</cite> you always have to check for that case if you access it.</p> </div> <div class="section" id="using-a-decorator"> <h2>Using a decorator<a class="headerlink" href="#using-a-decorator" title="Permalink to this headline">¶</a></h2> <p>You can also use the <cite>simplefilter</cite> decorator from the <cite>pygments.filter</cite> module:</p> <div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">pygments.util</span> <span class="kn">import</span> <span class="n">get_bool_opt</span> <span class="kn">from</span> <span class="nn">pygments.token</span> <span class="kn">import</span> <span class="n">Name</span> <span class="kn">from</span> <span class="nn">pygments.filter</span> <span class="kn">import</span> <span class="n">simplefilter</span> <span class="nd">@simplefilter</span> <span class="k">def</span> <span class="nf">uncolor</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">lexer</span><span class="p">,</span> <span class="n">stream</span><span class="p">,</span> <span class="n">options</span><span class="p">):</span> <span class="n">class_too</span> <span class="o">=</span> <span class="n">get_bool_opt</span><span class="p">(</span><span class="n">options</span><span class="p">,</span> <span class="s1">'classtoo'</span><span class="p">)</span> <span class="k">for</span> <span class="n">ttype</span><span class="p">,</span> <span class="n">value</span> <span class="ow">in</span> <span class="n">stream</span><span class="p">:</span> <span class="k">if</span> <span class="n">ttype</span> <span class="ow">is</span> <span class="n">Name</span><span class="o">.</span><span class="n">Function</span> <span class="ow">or</span> <span class="p">(</span><span class="n">class_too</span> <span class="ow">and</span> <span class="n">ttype</span> <span class="ow">is</span> <span class="n">Name</span><span class="o">.</span><span class="n">Class</span><span class="p">):</span> <span class="n">ttype</span> <span class="o">=</span> <span class="n">Name</span> <span class="k">yield</span> <span class="n">ttype</span><span class="p">,</span> <span class="n">value</span> </pre></div> </div> <p>The decorator automatically subclasses an internal filter class and uses the decorated function as a method for filtering. (That’s why there is a <cite>self</cite> argument that you probably won’t end up using in the method.)</p> </div> </div> </div> </div> </div> <div class="clearer"></div> </div> <div class="footer" role="contentinfo"> © Copyright 2006-2017, Georg Brandl and Pygments contributors. Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.7.6. <br/> Pygments logo created by <a href="http://joelunger.com">Joel Unger</a>. Backgrounds from <a href="http://subtlepatterns.com">subtlepatterns.com</a>. </div> </div> </body> </html>

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