Add safe_html() for XSS-safe WYSIWYG HTML sanitization

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Co-Authored-By: Claude <noreply@anthropic.com>

vendor/ezyang/htmlpurifier/library/HTMLPurifier/HTMLModule/Edit.php

@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * XHTML 1.1 Edit Module, defines editing-related elements. Text Extension
+ * Module.
+ */
+class HTMLPurifier_HTMLModule_Edit extends HTMLPurifier_HTMLModule
+{
+
+    /**
+     * @type string
+     */
+    public $name = 'Edit';
+
+    /**
+     * @param HTMLPurifier_Config $config
+     */
+    public function setup($config)
+    {
+        $contents = 'Chameleon: #PCDATA | Inline ! #PCDATA | Flow';
+        $attr = array(
+            'cite' => 'URI',
+            // 'datetime' => 'Datetime', // not implemented
+        );
+        $this->addElement('del', 'Inline', $contents, 'Common', $attr);
+        $this->addElement('ins', 'Inline', $contents, 'Common', $attr);
+    }
+
+    // HTML 4.01 specifies that ins/del must not contain block
+    // elements when used in an inline context, chameleon is
+    // a complicated workaround to achieve this effect
+
+    // Inline context ! Block context (exclamation mark is
+    // separator, see getChildDef for parsing)
+
+    /**
+     * @type bool
+     */
+    public $defines_child_def = true;
+
+    /**
+     * @param HTMLPurifier_ElementDef $def
+     * @return HTMLPurifier_ChildDef_Chameleon
+     */
+    public function getChildDef($def)
+    {
+        if ($def->content_model_type != 'chameleon') {
+            return false;
+        }
+        $value = explode('!', $def->content_model);
+        return new HTMLPurifier_ChildDef_Chameleon($value[0], $value[1]);
+    }
+}
+
+// vim: et sw=4 sts=4