[3.1.0] Add support for !important, with %CSS.AllowImportant

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1578 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/AttrDef/CSS/ImportantDecorator.php

@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * Decorator which enables !important to be used in CSS values.
+ */
+class HTMLPurifier_AttrDef_CSS_ImportantDecorator
+{
+    protected $def, $allow;
+    
+    /**
+     * @param $def Definition to wrap
+     * @param $allow Whether or not to allow !important
+     */
+    public function __construct($def, $allow = false) {
+        $this->def = $def;
+        $this->allow = $allow;
+    }
+    /**
+     * Intercepts and removes !important if necessary
+     */
+    public function validate($string, $config, $context) {
+        // test for ! and important tokens
+        $string = trim($string);
+        $is_important = false;
+        // :TODO: optimization: test directly for !important and ! important
+        if (strlen($string) >= 9 && substr($string, -9) === 'important') {
+            $temp = rtrim(substr($string, 0, -9));
+            // use a temp, because we might want to restore important
+            if (strlen($temp) >= 1 && substr($temp, -1) === '!') {
+                $string = rtrim(substr($temp, 0, -1));
+                $is_important = true;
+            }
+        }
+        $string = $this->def->validate($string, $config, $context);
+        if ($this->allow && $is_important) $string .= ' !important';
+        return $string;
+    }
+}