[1.4.0] YouTube preservation code added to the core by adding HTMLPurifier_Filter hierarchy.

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@673 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/Filter.php

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+<?php
+
+/**
+ * Represents a pre or post processing filter on HTML Purifier's output
+ * 
+ * Sometimes, a little ad-hoc fixing of HTML has to be done before
+ * it gets sent through HTML Purifier: you can use filters to acheive
+ * this effect. For instance, YouTube videos can be preserved using
+ * this manner. You could have used a decorator for this task, but
+ * PHP's support for them is not terribly robust, so we're going
+ * to just loop through the filters.
+ * 
+ * Filters should be exited first in, last out. If there are three filters,
+ * named 1, 2 and 3, the order of execution should go 1->preFilter,
+ * 2->preFilter, 3->preFilter, purify, 3->postFilter, 2->postFilter,
+ * 1->postFilter.
+ */
+
+class HTMLPurifier_Filter
+{
+    
+    /**
+     * Name of the filter for identification purposes
+     */
+    var $name;
+    
+    /**
+     * Pre-processor function, handles HTML before HTML Purifier 
+     */
+    function preFilter($html, $config, &$context) {}
+    
+    /**
+     * Post-processor function, handles HTML after HTML Purifier
+     */
+    function postFilter($html, $config, &$context) {}
+    
+}
+
+?>

library/HTMLPurifier/Filter/YouTube.php

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+<?php
+
+require_once 'HTMLPurifier/Filter.php';
+
+class HTMLPurifier_Filter_YouTube extends HTMLPurifier_Filter
+{
+    
+    var $name = 'YouTube preservation';
+    
+    function preFilter($html, $config, &$context) {
+        $pre_regex = '#<object[^>]+>.+?'.
+            'http://www.youtube.com/v/([A-Za-z0-9]+).+?</object>#';
+        $pre_replace = '<span class="youtube-embed">\1</span>';
+        return preg_replace($pre_regex, $pre_replace, $html);
+    }
+    
+    function postFilter($html, $config, &$context) {
+        $post_regex = '#<span class="youtube-embed">([A-Za-z0-9]+)</span>#';
+        $post_replace = '<object width="425" height="350" '.
+            'data="http://www.youtube.com/v/\1">'.
+            '<param name="movie" value="http://www.youtube.com/v/\1"></param>'.
+            '<param name="wmode" value="transparent"></param>'.
+            '<!--[if IE]>'.
+            '<embed src="http://www.youtube.com/v/\1"'.
+            'type="application/x-shockwave-flash"'.
+            'wmode="transparent" width="425" height="350" />'.
+            '<![endif]-->'.
+            '</object>';
+        return preg_replace($post_regex, $post_replace, $html);
+    }
+    
+}
+
+?>