library/HTMLPurifier/DefinitionCache.php

   1 <?php
   2
   3 /**
   4  * Abstract class representing Definition cache managers that implements
   5  * useful common methods and is a factory.
   6  * @todo Create a separate maintenance file advanced users can use to
   7  *       cache their custom HTMLDefinition, which can be loaded
   8  *       via a configuration directive
   9  * @todo Implement memcached
  10  */
  11 abstract class HTMLPurifier_DefinitionCache
  12 {
  13     /**
  14      * @type string
  15      */
  16     public $type;
  17
  18     /**
  19      * @param string $type Type of definition objects this instance of the
  20      *      cache will handle.
  21      */
  22     public function __construct($type)
  23     {
  24         $this->type = $type;
  25     }
  26
  27     /**
  28      * Generates a unique identifier for a particular configuration
  29      * @param HTMLPurifier_Config $config Instance of HTMLPurifier_Config
  30      * @return string
  31      */
  32     public function generateKey($config)
  33     {
  34         return $config->version . ',' . // possibly replace with function calls
  35                $config->getBatchSerial($this->type) . ',' .
  36                $config->get($this->type . '.DefinitionRev');
  37     }
  38
  39     /**
  40      * Tests whether or not a key is old with respect to the configuration's
  41      * version and revision number.
  42      * @param string $key Key to test
  43      * @param HTMLPurifier_Config $config Instance of HTMLPurifier_Config to test against
  44      * @return bool
  45      */
  46     public function isOld($key, $config)
  47     {
  48         if (substr_count($key, ',') < 2) {
  49             return true;
  50         }
  51         list($version, $hash, $revision) = explode(',', $key, 3);
  52         $compare = version_compare($version, $config->version);
  53         // version mismatch, is always old
  54         if ($compare != 0) {
  55             return true;
  56         }
  57         // versions match, ids match, check revision number
  58         if ($hash == $config->getBatchSerial($this->type) &&
  59             $revision < $config->get($this->type . '.DefinitionRev')) {
  60             return true;
  61         }
  62         return false;
  63     }
  64
  65     /**
  66      * Checks if a definition's type jives with the cache's type
  67      * @note Throws an error on failure
  68      * @param HTMLPurifier_Definition $def Definition object to check
  69      * @return bool true if good, false if not
  70      */
  71     public function checkDefType($def)
  72     {
  73         if ($def->type !== $this->type) {
  74             trigger_error("Cannot use definition of type {$def->type} in cache for {$this->type}");
  75             return false;
  76         }
  77         return true;
  78     }
  79
  80     /**
  81      * Adds a definition object to the cache
  82      * @param HTMLPurifier_Definition $def
  83      * @param HTMLPurifier_Config $config
  84      */
  85     abstract public function add($def, $config);
  86
  87     /**
  88      * Unconditionally saves a definition object to the cache
  89      * @param HTMLPurifier_Definition $def
  90      * @param HTMLPurifier_Config $config
  91      */
  92     abstract public function set($def, $config);
  93
  94     /**
  95      * Replace an object in the cache
  96      * @param HTMLPurifier_Definition $def
  97      * @param HTMLPurifier_Config $config
  98      */
  99     abstract public function replace($def, $config);
 100
 101     /**
 102      * Retrieves a definition object from the cache
 103      * @param HTMLPurifier_Config $config
 104      */
 105     abstract public function get($config);
 106
 107     /**
 108      * Removes a definition object to the cache
 109      * @param HTMLPurifier_Config $config
 110      */
 111     abstract public function remove($config);
 112
 113     /**
 114      * Clears all objects from cache
 115      * @param HTMLPurifier_Config $config
 116      */
 117     abstract public function flush($config);
 118
 119     /**
 120      * Clears all expired (older version or revision) objects from cache
 121      * @note Be carefuly implementing this method as flush. Flush must
 122      *       not interfere with other Definition types, and cleanup()
 123      *       should not be repeatedly called by userland code.
 124      * @param HTMLPurifier_Config $config
 125      */
 126     abstract public function cleanup($config);
 127 }
 128
 129 // vim: et sw=4 sts=4