[1.7.0] Add DefinitionCache decorators, implement Memory decorator

- Move serialization responsibility to Config
- Create DefinitionCacheFactory
- Implement Null definition cache

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1117 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/DefinitionCacheFactory.php

@@ -0,0 +1,82 @@
+<?php
+
+require_once 'HTMLPurifier/DefinitionCache.php';
+
+HTMLPurifier_ConfigSchema::define(
+    'Core', 'DefinitionCache', 'Serializer', 'string/null', '
+This directive defines which method to use when caching definitions,
+the complex data-type that makes HTML Purifier tick. Set to null
+to disable caching (not recommended, as you will see a definite
+performance degradation). This directive has been available since 1.7.0.
+');
+
+HTMLPurifier_ConfigSchema::defineAllowedValues(
+    'Core', 'DefinitionCache', array('Serializer')
+);
+
+
+/**
+ * Responsible for creating definition caches.
+ */
+class HTMLPurifier_DefinitionCacheFactory
+{
+    
+    var $caches = array('Serializer' => array());
+    var $decorators = array();
+    
+    /**
+     * Retrieves an instance of global definition cache factory.
+     * @static
+     */
+    function &instance($prototype = null) {
+        static $instance;
+        if ($prototype !== null) {
+            $instance = $prototype;
+        } elseif ($instance === null || $prototype === true) {
+            $instance = new HTMLPurifier_DefinitionCacheFactory();
+        }
+        return $instance;
+    }
+    
+    /**
+     * Factory method that creates a cache object based on configuration
+     * @param $name Name of definitions handled by cache
+     * @param $config Instance of HTMLPurifier_Config
+     */
+    function &create($type, $config) {
+        // only one implementation as for right now, $config will
+        // be used to determine implementation
+        $method = $config->get('Core', 'DefinitionCache');
+        if ($method === null) {
+            $null = new HTMLPurifier_DefinitionCache_Null($type);
+            return $null;
+        }
+        if (!empty($this->caches[$method][$type])) {
+            return $this->caches[$method][$type];
+        }
+        $cache = new HTMLPurifier_DefinitionCache_Serializer($type);
+        foreach ($this->decorators as $decorator) {
+            $new_cache = $decorator->decorate($cache);
+            // prevent infinite recursion in PHP 4
+            unset($cache);
+            $cache = $new_cache;
+        }
+        $this->caches[$method][$type] = $cache;
+        return $this->caches[$method][$type];
+    }
+    
+    /**
+     * Registers a decorator to add to all new cache objects
+     * @param 
+     */
+    function addDecorator($decorator) {
+        if (is_string($decorator)) {
+            $class = "HTMLPurifier_DefinitionCache_Decorator_$decorator";
+            $decorator = new $class;
+        }
+        $this->decorators[] = $decorator;
+    }
+    
+}
+
+?>