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797 lines
26 KiB
HTML
797 lines
26 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<meta name="description" content="Tutorial for customizing HTML Purifier's tag and attribute sets." />
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<link rel="stylesheet" type="text/css" href="style.css" />
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<title>Customize - HTML Purifier</title>
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</head><body>
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<h1 class="subtitled">Customize!</h1>
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<div class="subtitle">HTML Purifier is a Swiss-Army Knife</div>
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<div id="filing">Filed under End-User</div>
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<div id="index">Return to the <a href="index.html">index</a>.</div>
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<div id="home"><a href="http://htmlpurifier.org/">HTML Purifier</a> End-User Documentation</div>
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<p>
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You may have heard of the <a href="dev-advanced-api.html">Advanced API</a>.
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If you're interested in reading dry prose and boring functional
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specifications, feel free to click that link to get a no-nonsense overview
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on the Advanced API. For the rest of us, there's this tutorial. By the time
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you're finished reading this, you should have a pretty good idea on
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how to implement custom tags and attributes that HTML Purifier may not have.
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</p>
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<h2>Is it necessary?</h2>
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<p>
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Before we even write any code, it is paramount to consider whether or
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not the code we're writing is necessary or not. HTML Purifier, by default,
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contains a large set of elements and attributes: large enough so that
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<em>any</em> element or attribute in XHTML 1.0 or 1.1 (and its HTML variants)
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that can be safely used by the general public is implemented.
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</p>
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<p>
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So what needs to be implemented? (Feel free to skip this section if
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you know what you want).
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</p>
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<h3>XHTML 1.0</h3>
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<p>
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All of the modules listed below are based off of the
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<a href="http://www.w3.org/TR/2001/REC-xhtml-modularization-20010410/abstract_modules.html#sec_5.2.">modularization of
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XHTML</a>, which, while technically for XHTML 1.1, is quite a useful
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resource.
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</p>
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<ul>
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<li>Structure</li>
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<li>Frames</li>
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<li>Applets (deprecated)</li>
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<li>Forms</li>
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<li>Image maps</li>
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<li>Objects</li>
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<li>Frames</li>
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<li>Events</li>
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<li>Meta-information</li>
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<li>Style sheets</li>
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<li>Link (not hypertext)</li>
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<li>Base</li>
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<li>Name</li>
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</ul>
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<p>
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If you don't recognize it, you probably don't need it. But the curious
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can look all of these modules up in the above-mentioned document. Note
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that inline scripting comes packaged with HTML Purifier (more on this
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later).
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</p>
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<h3>XHTML 1.1</h3>
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<p>
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As of HTMLPurifier 2.1.0, we have implemented the
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<a href="http://www.w3.org/TR/2001/REC-ruby-20010531/">Ruby module</a>,
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which defines a set of tags
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for publishing short annotations for text, used mostly in Japanese
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and Chinese school texts, but applicable for positioning any text (not
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limited to translations) above or below other corresponding text.
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</p>
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<h3>XHTML 2.0</h3>
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<p>
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<a href="http://www.w3.org/TR/xhtml2/">XHTML 2.0</a> is still a
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working draft, so any elements introduced in the
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specification have not been implemented and will not be implemented
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until we get a recommendation or proposal. Because XHTML 2.0 is
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an entirely new markup language, implementing rules for it will be
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no easy task.
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</p>
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<h3>HTML 5</h3>
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<p>
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<a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML 5</a>
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is a fork of HTML 4.01 by WHATWG, who believed that XHTML 2.0 was headed
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in the wrong direction. It too is a working draft, and may change
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drastically before publication, but it should be noted that the
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<code>canvas</code> tag has been implemented by many browser vendors.
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</p>
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<h3>Proprietary</h3>
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<p>
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There are a number of proprietary tags still in the wild. Many of them
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have been documented in <a href="ref-proprietary-tags.txt">ref-proprietary-tags.txt</a>,
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but there is currently no implementation for any of them.
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</p>
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<h3>Extensions</h3>
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<p>
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There are also a number of other XML languages out there that can
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be embedded in HTML documents: two of the most popular are MathML and
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SVG, and I frequently get requests to implement these. But they are
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expansive, comprehensive specifications, and it would take far too long
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to implement them <em>correctly</em> (most systems I've seen go as far
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as whitelisting tags and no further; come on, what about nesting!)
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</p>
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<p>
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Word of warning: HTML Purifier is currently <em>not</em> namespace
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aware.
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</p>
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<h2>Giving back</h2>
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<p>
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As you may imagine from the details above (don't be abashed if you didn't
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read it all: a glance over would have done), there's quite a bit that
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HTML Purifier doesn't implement. Recent architectural changes have
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allowed HTML Purifier to implement elements and attributes that are not
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safe! Don't worry, they won't be activated unless you set %HTML.Trusted
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to true, but they certainly help out users who need to put, say, forms
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on their page and don't want to go through the trouble of reading this
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and implementing it themself.
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</p>
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<p>
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So any of the above that you implement for your own application could
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help out some other poor sap on the other side of the globe. Help us
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out, and send back code so that it can be hammered into a module and
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released with the core. Any code would be greatly appreciated!
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</p>
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<h2>And now...</h2>
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<p>
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Enough philosophical talk, time for some code:
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</p>
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<pre>$config = HTMLPurifier_Config::createDefault();
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$config->set('HTML', 'DefinitionID', 'enduser-customize.html tutorial');
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$config->set('HTML', 'DefinitionRev', 1);
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$def = $config->getHTMLDefinition(true);</pre>
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<p>
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Assuming that HTML Purifier has already been properly loaded (hint:
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include <code>HTMLPurifier.auto.php</code>), this code will set up
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the environment that you need to start customizing the HTML definition.
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What's going on?
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</p>
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<ul>
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<li>
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The first three lines are regular configuration code:
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<ul>
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<li>
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%HTML.DefinitionID is set to a unique identifier for your
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custom HTML definition. This prevents it from clobbering
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other custom definitions on the same installation.
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</li>
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<li>
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%HTML.DefinitionRev is a revision integer of your HTML
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definition. Because HTML definitions are cached, you'll need
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to increment this whenever you make a change in order to flush
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the cache.
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</li>
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</ul>
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</li>
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<li>
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The fourth line retrieves a raw <code>HTMLPurifier_HTMLDefinition</code>
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object that we will be tweaking. If the parameter was removed, we
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would be retrieving a fully formed definition object, which is somewhat
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useless for customization purposes.
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</li>
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</ul>
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<h3>Broken backwards-compatibility</h3>
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<p>
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Those of you who have already been twiddling around with the raw
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HTML definition object, you'll be noticing that you're getting an error
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when you attempt to retrieve the raw definition object without specifying
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a DefinitionID. It is vital to caching (see below) that you make a unique
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name for your customized definition, so make up something right now and
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things will operate again.
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</p>
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<h2>Turn off caching</h2>
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<p>
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To make development easier, we're going to temporarily turn off
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definition caching:
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</p>
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<pre>$config = HTMLPurifier_Config::createDefault();
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$config->set('HTML', 'DefinitionID', 'enduser-customize.html tutorial');
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$config->set('HTML', 'DefinitionRev', 1);
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<strong>$config->set('Cache', 'DefinitionImpl', null); // remove this later!</strong>
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$def = $config->getHTMLDefinition(true);</pre>
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<p>
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A few things should be mentioned about the caching mechanism before
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we move on. For performance reasons, HTML Purifier caches generated
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<code>HTMLPurifier_Definition</code> objects in serialized files
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stored (by default) in <code>library/HTMLPurifier/DefinitionCache/Serializer</code>.
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A lot of processing is done in order to create these objects, so it
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makes little sense to repeat the same processing over and over again
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whenever HTML Purifier is called.
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</p>
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<p>
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In order to identify a cache entry, HTML Purifier uses three variables:
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the library's version number, the value of %HTML.DefinitionRev and
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a serial of relevant configuration. Whenever any of these changes,
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a new HTML definition is generated. Notice that there is no way
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for the definition object to track changes to customizations: here, it
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is up to you to supply appropriate information to DefinitionID and
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DefinitionRev.
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</p>
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<h2 id="addAttribute">Add an attribute</h2>
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<p>
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For this example, we're going to implement the <code>target</code> attribute found
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on <code>a</code> elements. To implement an attribute, we have to
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ask a few questions:
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</p>
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<ol>
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<li>What element is it found on?</li>
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<li>What is its name?</li>
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<li>Is it required or optional?</li>
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<li>What are valid values for it?</li>
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</ol>
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<p>
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The first three are easy: the element is <code>a</code>, the attribute
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is <code>target</code>, and it is not a required attribute. (If it
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was required, we'd need to append an asterisk to the attribute name,
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you'll see an example of this in the addElement() example).
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</p>
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<p>
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The last question is a little trickier.
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Lets allow the special values: _blank, _self, _target and _top.
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The form of this is called an <strong>enumeration</strong>, a list of
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valid values, although only one can be used at a time. To translate
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this into code form, we write:
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</p>
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<pre>$config = HTMLPurifier_Config::createDefault();
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$config->set('HTML', 'DefinitionID', 'enduser-customize.html tutorial');
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$config->set('HTML', 'DefinitionRev', 1);
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$config->set('Cache', 'DefinitionImpl', null); // remove this later!
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$def = $config->getHTMLDefinition(true);
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<strong>$def->addAttribute('a', 'target', 'Enum#_blank,_self,_target,_top');</strong></pre>
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<p>
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The <code>Enum#_blank,_self,_target,_top</code> does all the magic.
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The string is split into two parts, separated by a hash mark (#):
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</p>
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<ol>
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<li>The first part is the name of what we call an <code>AttrDef</code></li>
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<li>The second part is the parameter of the above-mentioned <code>AttrDef</code></li>
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</ol>
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<p>
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If that sounds vague and generic, it's because it is! HTML Purifier defines
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an assortment of different attribute types one can use, and each of these
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has their own specialized parameter format. Here are some of the more useful
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ones:
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</p>
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<table class="table">
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<thead>
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<tr>
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<th>Type</th>
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<th>Format</th>
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<th>Description</th>
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</tr>
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</thead>
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<tbody>
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<tr>
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<th>Enum</th>
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<td><em>[s:]</em>value1,value2,...</td>
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<td>
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Attribute with a number of valid values, one of which may be used. When
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s: is present, the enumeration is case sensitive.
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</td>
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</tr>
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<tr>
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<th>Bool</th>
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<td>attribute_name</td>
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<td>
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Boolean attribute, with only one valid value: the name
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of the attribute.
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</td>
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</tr>
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<tr>
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<th>CDATA</th>
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<td></td>
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<td>
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Attribute of arbitrary text. Can also be referred to as <strong>Text</strong>
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(the specification makes a semantic distinction between the two).
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</td>
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</tr>
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<tr>
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<th>ID</th>
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<td></td>
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<td>
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Attribute that specifies a unique ID
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</td>
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</tr>
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<tr>
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<th>Pixels</th>
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<td></td>
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<td>
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Attribute that specifies an integer pixel length
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</td>
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</tr>
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<tr>
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<th>Length</th>
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<td></td>
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<td>
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Attribute that specifies a pixel or percentage length
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</td>
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</tr>
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<tr>
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<th>NMTOKENS</th>
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<td></td>
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<td>
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Attribute that specifies a number of name tokens, example: the
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<code>class</code> attribute
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</td>
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</tr>
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<tr>
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<th>URI</th>
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<td></td>
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<td>
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Attribute that specifies a URI, example: the <code>href</code>
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attribute
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</td>
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</tr>
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<tr>
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<th>Number</th>
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<td></td>
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<td>
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Attribute that specifies an positive integer number
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</td>
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</tr>
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</tbody>
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</table>
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<p>
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For a complete list, consult
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<a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/AttrTypes.php"><code>library/HTMLPurifier/AttrTypes.php</code></a>;
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more information on attributes that accept parameters can be found on their
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respective includes in
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<a href="http://repo.or.cz/w/htmlpurifier.git?a=tree;hb=HEAD;f=library/HTMLPurifier/AttrDef"><code>library/HTMLPurifier/AttrDef</code></a>.
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</p>
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<p>
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Sometimes, the restrictive list in AttrTypes just doesn't cut it. Don't
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sweat: you can also use a fully instantiated object as the value. The
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equivalent, verbose form of the above example is:
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</p>
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<pre>$config = HTMLPurifier_Config::createDefault();
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$config->set('HTML', 'DefinitionID', 'enduser-customize.html tutorial');
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$config->set('HTML', 'DefinitionRev', 1);
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$config->set('Cache', 'DefinitionImpl', null); // remove this later!
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$def = $config->getHTMLDefinition(true);
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<strong>$def->addAttribute('a', 'target', new HTMLPurifier_AttrDef_Enum(
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array('_blank','_self','_target','_top')
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));</strong></pre>
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<p>
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Trust me, you'll learn to love the shorthand.
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</p>
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<h2>Add an element</h2>
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<p>
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Adding attributes is really small-fry stuff, though, and it was possible
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to add them (albeit a bit more wordy) prior to 2.0. The real gem of
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the Advanced API is adding elements. There are five questions to
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ask when adding a new element:
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</p>
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<ol>
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<li>What is the element's name?</li>
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<li>What content set does this element belong to?</li>
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<li>What are the allowed children of this element?</li>
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<li>What attributes does the element allow that are general?</li>
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<li>What attributes does the element allow that are specific to this element?</li>
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</ol>
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<p>
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It's a mouthful, and you'll be slightly lost if your not familiar with
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the HTML specification, so let's explain them step by step.
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</p>
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<h3>Content set</h3>
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<p>
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The HTML specification defines two major content sets: Inline
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and Block. Each of these
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content sets contain a list of elements: Inline contains things like
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<code>span</code> and <code>b</code> while Block contains things like
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<code>div</code> and <code>blockquote</code>.
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</p>
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<p>
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These content sets amount to a macro mechanism for HTML definition. Most
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elements in HTML are organized into one of these two sets, and most
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elements in HTML allow elements from one of these sets. If we had
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to write each element verbatim into each other element's allowed
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children, we would have ridiculously large lists; instead we use
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content sets to compactify the declaration.
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</p>
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<p>
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Practically speaking, there are several useful values you can use here:
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</p>
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<table class="table">
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<thead>
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<tr>
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<th>Content set</th>
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<th>Description</th>
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</tr>
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</thead>
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<tbody>
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<tr>
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<th>Inline</th>
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<td>Character level elements, text</td>
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</tr>
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<tr>
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<th>Block</th>
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<td>Block-like elements, like paragraphs and lists</td>
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</tr>
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<tr>
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<th><em>false</em></th>
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<td>
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Any element that doesn't fit into the mold, for example <code>li</code>
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or <code>tr</code>
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</td>
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</tr>
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</tbody>
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</table>
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<p>
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By specifying a valid value here, all other elements that use that
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content set will also allow your element, without you having to do
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anything. If you specify <em>false</em>, you'll have to register
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your element manually.
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</p>
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<h3>Allowed children</h3>
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<p>
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Allowed children defines the elements that this element can contain.
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The allowed values may range from none to a complex regexp depending on
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your element.
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</p>
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<p>
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If you've ever taken a look at the HTML DTD's before, you may have
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noticed declarations like this:
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</p>
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<pre><!ELEMENT LI - O (%flow;)* -- list item --></pre>
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<p>
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The <code>(%flow;)*</code> indicates the allowed children of the
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<code>li</code> tag: <code>li</code> allows any number of flow
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elements as its children. (The <code>- O</code> allows the closing tag to be
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omitted, though in XML this is not allowed.) In HTML Purifier,
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we'd write it like <code>Flow</code> (here's where the content sets
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we were discussing earlier come into play). There are three shorthand
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content models you can specify:
|
|
</p>
|
|
|
|
<table class="table">
|
|
<thead>
|
|
<tr>
|
|
<th>Content model</th>
|
|
<th>Description</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<th>Empty</th>
|
|
<td>No children allowed, like <code>br</code> or <code>hr</code></td>
|
|
</tr>
|
|
<tr>
|
|
<th>Inline</th>
|
|
<td>Any number of inline elements and text, like <code>span</code></td>
|
|
</tr>
|
|
<tr>
|
|
<th>Flow</th>
|
|
<td>Any number of inline elements, block elements and text, like <code>div</code></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>
|
|
This covers 90% of all the cases out there, but what about elements that
|
|
break the mold like <code>ul</code>? This guy requires at least one
|
|
child, and the only valid children for it are <code>li</code>. The
|
|
content model is: <code>Required: li</code>. There are two parts: the
|
|
first type determines what <code>ChildDef</code> will be used to validate
|
|
content models. The most common values are:
|
|
</p>
|
|
|
|
<table class="table">
|
|
<thead>
|
|
<tr>
|
|
<th>Type</th>
|
|
<th>Description</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<th>Required</th>
|
|
<td>Children must be one or more of the valid elements</td>
|
|
</tr>
|
|
<tr>
|
|
<th>Optional</th>
|
|
<td>Children can be any number of the valid elements</td>
|
|
</tr>
|
|
<tr>
|
|
<th>Custom</th>
|
|
<td>Children must follow the DTD-style regex</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>
|
|
You can also implement your own <code>ChildDef</code>: this was done
|
|
for a few special cases in HTML Purifier such as <code>Chameleon</code>
|
|
(for <code>ins</code> and <code>del</code>), <code>StrictBlockquote</code>
|
|
and <code>Table</code>.
|
|
</p>
|
|
|
|
<p>
|
|
The second part specifies either valid elements or a regular expression.
|
|
Valid elements are separated with horizontal bars (|), i.e.
|
|
"<code>a | b | c</code>". Use #PCDATA to represent plain text.
|
|
Regular expressions are based off of DTD's style:
|
|
</p>
|
|
|
|
<ul>
|
|
<li>Parentheses () are used for grouping</li>
|
|
<li>Commas (,) separate elements that should come one after another</li>
|
|
<li>Horizontal bars (|) indicate one or the other elements should be used</li>
|
|
<li>Plus signs (+) are used for a one or more match</li>
|
|
<li>Asterisks (*) are used for a zero or more match</li>
|
|
<li>Question marks (?) are used for a zero or one match</li>
|
|
</ul>
|
|
|
|
<p>
|
|
For example, "<code>a, b?, (c | d), e+, f*</code>" means "In this order,
|
|
one <code>a</code> element, at most one <code>b</code> element,
|
|
one <code>c</code> or <code>d</code> element (but not both), one or more
|
|
<code>e</code> elements, and any number of <code>f</code> elements."
|
|
Regex veterans should be able to jump right in, and those not so savvy
|
|
can always copy-paste W3C's content model definitions into HTML Purifier
|
|
and hope for the best.
|
|
</p>
|
|
|
|
<p>
|
|
A word of warning: while the regex format is extremely flexible on
|
|
the developer's side, it is
|
|
quite unforgiving on the user's side. If the user input does not <em>exactly</em>
|
|
match the specification, the entire contents of the element will
|
|
be nuked. This is why there is are specific content model types like
|
|
Optional and Required: while they could be implemented as <code>Custom:
|
|
(valid | elements)*</code>, the custom classes contain special recovery
|
|
measures that make sure as much of the user's original content gets
|
|
through. HTML Purifier's core, as a rule, does not use Custom.
|
|
</p>
|
|
|
|
<p>
|
|
One final note: you can also use Content Sets inside your valid elements
|
|
lists or regular expressions. In fact, the three shorthand content models
|
|
mentioned above are just that: abbreviations:
|
|
</p>
|
|
|
|
<table class="table">
|
|
<thead>
|
|
<tr>
|
|
<th>Content model</th>
|
|
<th>Implementation</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<th>Inline</th>
|
|
<td>Optional: Inline | #PCDATA</td>
|
|
</tr>
|
|
<tr>
|
|
<th>Flow</th>
|
|
<td>Optional: Flow | #PCDATA</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>
|
|
When the definition is compiled, Inline will be replaced with a
|
|
horizontal-bar separated list of inline elements. Also, notice that
|
|
it does not contain text: you have to specify that yourself.
|
|
</p>
|
|
|
|
<h3>Common attributes</h3>
|
|
|
|
<p>
|
|
Congratulations: you have just gotten over the proverbial hump (Allowed
|
|
children). Common attributes is much simpler, and boils down to
|
|
one question: does your element have the <code>id</code>, <code>style</code>,
|
|
<code>class</code>, <code>title</code> and <code>lang</code> attributes?
|
|
If so, you'll want to specify the <code>Common</code> attribute collection,
|
|
which contains these five attributes that are found on almost every
|
|
HTML element in the specification.
|
|
</p>
|
|
|
|
<p>
|
|
There are a few more collections, but they're really edge cases:
|
|
</p>
|
|
|
|
<table class="table">
|
|
<thead>
|
|
<tr>
|
|
<th>Collection</th>
|
|
<th>Attributes</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<th>I18N</th>
|
|
<td><code>lang</code>, possibly <code>xml:lang</code></td>
|
|
</tr>
|
|
<tr>
|
|
<th>Core</th>
|
|
<td><code>style</code>, <code>class</code>, <code>id</code> and <code>title</code></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>
|
|
Common is a combination of the above-mentioned collections.
|
|
</p>
|
|
|
|
<p class="aside">
|
|
Readers familiar with the modularization may have noticed that the Core
|
|
attribute collection differs from that specified by the <a
|
|
href="http://www.w3.org/TR/xhtml-modularization/abstract_modules.html#s_commonatts">abstract
|
|
modules of the XHTML Modularization 1.1</a>. We believe this section
|
|
to be in error, as <code>br</code> permits the use of the <code>style</code>
|
|
attribute even though it uses the <code>Core</code> collection, and
|
|
the DTD and XML Schemas supplied by W3C support our interpretation.
|
|
</p>
|
|
|
|
<h3>Attributes</h3>
|
|
|
|
<p>
|
|
If you didn't read the <a href="#addAttribute">earlier section on
|
|
adding attributes</a>, read it now. The last parameter is simply
|
|
an array of attribute names to attribute implementations, in the exact
|
|
same format as <code>addAttribute()</code>.
|
|
</p>
|
|
|
|
<h3>Putting it all together</h3>
|
|
|
|
<p>
|
|
We're going to implement <code>form</code>. Before we embark, lets
|
|
grab a reference implementation from over at the
|
|
<a href="http://www.w3.org/TR/html4/sgml/loosedtd.html">transitional DTD</a>:
|
|
</p>
|
|
|
|
<pre><!ELEMENT FORM - - (%flow;)* -(FORM) -- interactive form -->
|
|
<!ATTLIST FORM
|
|
%attrs; -- %coreattrs, %i18n, %events --
|
|
action %URI; #REQUIRED -- server-side form handler --
|
|
method (GET|POST) GET -- HTTP method used to submit the form--
|
|
enctype %ContentType; "application/x-www-form-urlencoded"
|
|
accept %ContentTypes; #IMPLIED -- list of MIME types for file upload --
|
|
name CDATA #IMPLIED -- name of form for scripting --
|
|
onsubmit %Script; #IMPLIED -- the form was submitted --
|
|
onreset %Script; #IMPLIED -- the form was reset --
|
|
target %FrameTarget; #IMPLIED -- render in this frame --
|
|
accept-charset %Charsets; #IMPLIED -- list of supported charsets --
|
|
></pre>
|
|
|
|
<p>
|
|
Juicy! With just this, we can answer four of our five questions:
|
|
</p>
|
|
|
|
<ol>
|
|
<li>What is the element's name? <strong>form</strong></li>
|
|
<li>What content set does this element belong to? <strong>Block</strong>
|
|
(this needs a little sleuthing, I find the easiest way is to search
|
|
the DTD for <code>FORM</code> and determine which set it is in.)</li>
|
|
<li>What are the allowed children of this element? <strong>One
|
|
or more flow elements, but no nested <code>form</code>s</strong></li>
|
|
<li>What attributes does the element allow that are general? <strong>Common</strong></li>
|
|
<li>What attributes does the element allow that are specific to this element? <strong>A whole bunch, see ATTLIST;
|
|
we're going to the vital ones: <code>action</code>, <code>method</code> and <code>name</code></strong></li>
|
|
</ol>
|
|
|
|
<p>
|
|
Time for some code:
|
|
</p>
|
|
|
|
<pre>$config = HTMLPurifier_Config::createDefault();
|
|
$config->set('HTML', 'DefinitionID', 'enduser-customize.html tutorial');
|
|
$config->set('HTML', 'DefinitionRev', 1);
|
|
$config->set('Cache', 'DefinitionImpl', null); // remove this later!
|
|
$def = $config->getHTMLDefinition(true);
|
|
$def->addAttribute('a', 'target', new HTMLPurifier_AttrDef_Enum(
|
|
array('_blank','_self','_target','_top')
|
|
));
|
|
<strong>$form = $def->addElement(
|
|
'form', // name
|
|
'Block', // content set
|
|
'Flow', // allowed children
|
|
'Common', // attribute collection
|
|
array( // attributes
|
|
'action*' => 'URI',
|
|
'method' => 'Enum#get|post',
|
|
'name' => 'ID'
|
|
)
|
|
);
|
|
$form->excludes = array('form' => true);</strong></pre>
|
|
|
|
<p>
|
|
Each of the parameters corresponds to one of the questions we asked.
|
|
Notice that we added an asterisk to the end of the <code>action</code>
|
|
attribute to indicate that it is required. If someone specifies a
|
|
<code>form</code> without that attribute, the tag will be axed.
|
|
Also, the extra line at the end is a special extra declaration that
|
|
prevents forms from being nested within each other.
|
|
</p>
|
|
|
|
<p>
|
|
And that's all there is to it! Implementing the rest of the form
|
|
module is left as an exercise to the user; to see more examples
|
|
check the <a href="http://repo.or.cz/w/htmlpurifier.git?a=tree;hb=HEAD;f=library/HTMLPurifier/HTMLModule"><code>library/HTMLPurifier/HTMLModule/</code></a> directory
|
|
in your local HTML Purifier installation.
|
|
</p>
|
|
|
|
<h2>And beyond...</h2>
|
|
|
|
<p>
|
|
Perceptive users may have realized that, to a certain extent, we
|
|
have simply re-implemented the facilities of XML Schema or the
|
|
Document Type Definition. What you are seeing here, however, is
|
|
not just an XML Schema or Document Type Definition: it is a fully
|
|
expressive method of specifying the definition of HTML that is
|
|
a portable superset of the capabilities of the two above-mentioned schema
|
|
languages. What makes HTMLDefinition so powerful is the fact that
|
|
if we don't have an implementation for a content model or an attribute
|
|
definition, you can supply it yourself by writing a PHP class.
|
|
</p>
|
|
|
|
<p>
|
|
There are many facets of HTMLDefinition beyond the Advanced API I have
|
|
walked you through today. To find out more about these, you can
|
|
check out these source files:
|
|
</p>
|
|
|
|
<ul>
|
|
<li><a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/HTMLModule.php"><code>library/HTMLPurifier/HTMLModule.php</code></a></li>
|
|
<li><a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/ElementDef.php"><code>library/HTMLPurifier/ElementDef.php</code></a></li>
|
|
</ul>
|
|
|
|
</body></html>
|