<?php
/**
* Abstract class representing Definition cache managers that implements
* useful common methods and is a factory.
* @todo Create a separate maintenance file advanced users can use to
* cache their custom HTMLDefinition, which can be loaded
* via a configuration directive
* @todo Implement memcached
*/
abstract class HTMLPurifier_DefinitionCache
{
public $type;
/**
* @param $name Type of definition objects this instance of the
* cache will handle.
*/
public function __construct($type) {
$this->type = $type;
}
/**
* Generates a unique identifier for a particular configuration
* @param Instance of HTMLPurifier_Config
*/
public function generateKey($config) {
return $config->version . ',' . // possibly replace with function calls
$config->getBatchSerial($this->type) . ',' .
$config->get($this->type . '.DefinitionRev');
}
/**
* Tests whether or not a key is old with respect to the configuration's
* version and revision number.
* @param $key Key to test
* @param $config Instance of HTMLPurifier_Config to test against
*/
public function isOld($key, $config) {
if (substr_count($key, ',') < 2) return true;
list($version, $hash, $revision) = explode(',', $key, 3);
$compare = version_compare($version, $config->version);
// version mismatch, is always old
if ($compare != 0) return true;
// versions match, ids match, check revision number
if (
$hash == $config->getBatchSerial($this->type) &&
$revision < $config->get($this->type . '.DefinitionRev')
) return true;
return false;
}
/**
* Checks if a definition's type jives with the cache's type
* @note Throws an error on failure
* @param $def Definition object to check
* @return Boolean true if good, false if not
*/
public function checkDefType($def) {
if ($def->type !== $this->type) {
trigger_error("Cannot use definition of type {$def->type} in cache for {$this->type}");
return false;
}
return true;
}
/**
* Adds a definition object to the cache
*/
abstract public function add($def, $config);
/**
* Unconditionally saves a definition object to the cache
*/
abstract public function set($def, $config);
/**
* Replace an object in the cache
*/
abstract public function replace($def, $config);
/**
* Retrieves a definition object from the cache
*/
abstract public function get($config);
/**
* Removes a definition object to the cache
*/
abstract public function remove($config);
/**
* Clears all objects from cache
*/
abstract public function flush($config);
/**
* Clears all expired (older version or revision) objects from cache
* @note Be carefuly implementing this method as flush. Flush must
* not interfere with other Definition types, and cleanup()
* should not be repeatedly called by userland code.
*/
abstract public function cleanup($config);
}
// vim: et sw=4 sts=4
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