<?php

/**

 * Object Cache API

 *

 * @link http://codex.wordpress.org/Function_Reference/WP_Cache

 *

 * @package WordPress

 * @subpackage Cache

 */

/**

 * Adds data to the cache, if the cache key doesn't aleady exist.

 *

 * @since 2.0.0

 * @uses $wp_object_cache Object Cache Class

 * @see WP_Object_Cache::add()

 *

 * @param int|string $key The cache ID to use for retrieval later

 * @param mixed $data The data to add to the cache store

 * @param string $flag The group to add the cache to

 * @param int $expire When the cache data should be expired

 * @return unknown

 */

function wp_cache_add($key, $data, $flag = '', $expire = 0) {

	global $wp_object_cache;

	return $wp_object_cache->add($key, $data, $flag, $expire);

}

/**

 * Closes the cache.

 *

 * This function has ceased to do anything since WordPress 2.5. The

 * functionality was removed along with the rest of the persistant cache. This

 * does not mean that plugins can't implement this function when they need to

 * make sure that the cache is cleaned up after WordPress no longer needs it.

 *

 * @since 2.0.0

 *

 * @return bool Always returns True

 */

function wp_cache_close() {

	return true;

}

/**

 * Removes the cache contents matching ID and flag.

 *

 * @since 2.0.0

 * @uses $wp_object_cache Object Cache Class

 * @see WP_Object_Cache::delete()

 *

 * @param int|string $id What the contents in the cache are called

 * @param string $flag Where the cache contents are grouped

 * @return bool True on successful removal, false on failure

 */

function wp_cache_delete($id, $flag = '') {

	global $wp_object_cache;

	return $wp_object_cache->delete($id, $flag);

}

/**

 * Removes all cache items.

 *

 * @since 2.0.0

 * @uses $wp_object_cache Object Cache Class

 * @see WP_Object_Cache::flush()

 *

 * @return bool Always returns true

 */

function wp_cache_flush() {

	global $wp_object_cache;

	return $wp_object_cache->flush();

}

/**

 * Retrieves the cache contents from the cache by ID and flag.

 *

 * @since 2.0.0

 * @uses $wp_object_cache Object Cache Class

 * @see WP_Object_Cache::get()

 *

 * @param int|string $id What the contents in the cache are called

 * @param string $flag Where the cache contents are grouped

 * @return bool|mixed False on failure to retrieve contents or the cache

 *		contents on success

 */

function wp_cache_get($id, $flag = '') {

	global $wp_object_cache;

	return $wp_object_cache->get($id, $flag);

}

/**

 * Sets up Object Cache Global and assigns it.

 *

 * @since 2.0.0

 * @global WP_Object_Cache $wp_object_cache WordPress Object Cache

 */

function wp_cache_init() {

	$GLOBALS['wp_object_cache'] =& new WP_Object_Cache();

}

/**

 * Replaces the contents of the cache with new data.

 *

 * @since 2.0.0

 * @uses $wp_object_cache Object Cache Class

 * @see WP_Object_Cache::replace()

 *

 * @param int|string $id What to call the contents in the cache

 * @param mixed $data The contents to store in the cache

 * @param string $flag Where to group the cache contents

 * @param int $expire When to expire the cache contents

 * @return bool False if cache ID and group already exists, true on success

 */

function wp_cache_replace($key, $data, $flag = '', $expire = 0) {

	global $wp_object_cache;

	return $wp_object_cache->replace($key, $data, $flag, $expire);

}

/**

 * Saves the data to the cache.

 *

 * @since 2.0

 * @uses $wp_object_cache Object Cache Class

 * @see WP_Object_Cache::set()

 *

 * @param int|string $id What to call the contents in the cache

 * @param mixed $data The contents to store in the cache

 * @param string $flag Where to group the cache contents

 * @param int $expire When to expire the cache contents

 * @return bool False if cache ID and group already exists, true on success

 */

function wp_cache_set($key, $data, $flag = '', $expire = 0) {

	global $wp_object_cache;

	return $wp_object_cache->set($key, $data, $flag, $expire);

}

/**

 * Adds a group or set of groups to the list of global groups.

 *

 * @since 2.6.0

 *

 * @param string|array $groups A group or an array of groups to add

 */

function wp_cache_add_global_groups( $groups ) {

	// Default cache doesn't persist so nothing to do here.

	return;

}

/**

 * Adds a group or set of groups to the list of non-persistent groups.

 *

 * @since 2.6.0

 *

 * @param string|array $groups A group or an array of groups to add

 */

function wp_cache_add_non_persistent_groups( $groups ) {

	// Default cache doesn't persist so nothing to do here.

	return;

}

/**

 * WordPress Object Cache

 *

 * The WordPress Object Cache is used to save on trips to the database. The

 * Object Cache stores all of the cache data to memory and makes the cache

 * contents available by using a key, which is used to name and later retrieve

 * the cache contents.

 *

 * The Object Cache can be replaced by other caching mechanisms by placing files

 * in the wp-content folder which is looked at in wp-settings. If that file

 * exists, then this file will not be included.

 *

 * @package WordPress

 * @subpackage Cache

 * @since 2.0

 */

class WP_Object_Cache {

	/**

	 * Holds the cached objects

	 *

	 * @var array

	 * @access private

	 * @since 2.0.0

	 */

	var $cache = array ();

	/**

	 * Cache objects that do not exist in the cache

	 *

	 * @var array

	 * @access private

	 * @since 2.0.0

	 */

	var $non_existant_objects = array ();

	/**

	 * The amount of times the cache data was already stored in the cache.

	 *

	 * @since 2.5.0

	 * @access private

	 * @var int

	 */

	var $cache_hits = 0;

	/**

	 * Amount of times the cache did not have the request in cache

	 *

	 * @var int

	 * @access public

	 * @since 2.0.0

	 */

	var $cache_misses = 0;

	/**

	 * Adds data to the cache if it doesn't already exist.

	 *

	 * @uses WP_Object_Cache::get Checks to see if the cache already has data.

	 * @uses WP_Object_Cache::set Sets the data after the checking the cache

	 *		contents existance.

	 *

	 * @since 2.0.0

	 *

	 * @param int|string $id What to call the contents in the cache

	 * @param mixed $data The contents to store in the cache

	 * @param string $group Where to group the cache contents

	 * @param int $expire When to expire the cache contents

	 * @return bool False if cache ID and group already exists, true on success

	 */

	function add($id, $data, $group = 'default', $expire = '') {

		if (empty ($group))

			$group = 'default';

		if (false !== $this->get($id, $group, false))

			return false;

		return $this->set($id, $data, $group, $expire);

	}

	/**

	 * Remove the contents of the cache ID in the group

	 *

	 * If the cache ID does not exist in the group and $force parameter is set

	 * to false, then nothing will happen. The $force parameter is set to false

	 * by default.

	 *

	 * On success the group and the id will be added to the

	 * $non_existant_objects property in the class.

	 *

	 * @since 2.0.0

	 *

	 * @param int|string $id What the contents in the cache are called

	 * @param string $group Where the cache contents are grouped

	 * @param bool $force Optional. Whether to force the unsetting of the cache

	 *		ID in the group

	 * @return bool False if the contents weren't deleted and true on success

	 */

	function delete($id, $group = 'default', $force = false) {

		if (empty ($group))

			$group = 'default';

		if (!$force && false === $this->get($id, $group, false))

			return false;

		unset ($this->cache[$group][$id]);

		$this->non_existant_objects[$group][$id] = true;

		return true;

	}

	/**

	 * Clears the object cache of all data

	 *

	 * @since 2.0.0

	 *

	 * @return bool Always returns true

	 */

	function flush() {

		$this->cache = array ();

		return true;

	}

	/**

	 * Retrieves the cache contents, if it exists

	 *

	 * The contents will be first attempted to be retrieved by searching by the

	 * ID in the cache group. If the cache is hit (success) then the contents

	 * are returned.

	 *

	 * On failure, the $non_existant_objects property is checked and if the

	 * cache group and ID exist in there the cache misses will not be

	 * incremented. If not in the nonexistant objects property, then the cache

	 * misses will be incremented and the cache group and ID will be added to

	 * the nonexistant objects.

	 *

	 * @since 2.0.0

	 *

	 * @param int|string $id What the contents in the cache are called

	 * @param string $group Where the cache contents are grouped

	 * @return bool|mixed False on failure to retrieve contents or the cache

	 *		contents on success

	 */

	function get($id, $group = 'default') {

		if (empty ($group))

			$group = 'default';

		if (isset ($this->cache[$group][$id])) {

			$this->cache_hits += 1;

			if ( is_object($this->cache[$group][$id]) )

				return wp_clone($this->cache[$group][$id]);

			else

				return $this->cache[$group][$id];

		}

		if ( isset ($this->non_existant_objects[$group][$id]) )

			return false;

		$this->non_existant_objects[$group][$id] = true;

		$this->cache_misses += 1;

		return false;

	}

	/**

	 * Replace the contents in the cache, if contents already exist

	 *

	 * @since 2.0.0

	 * @see WP_Object_Cache::set()

	 *

	 * @param int|string $id What to call the contents in the cache

	 * @param mixed $data The contents to store in the cache

	 * @param string $group Where to group the cache contents

	 * @param int $expire When to expire the cache contents

	 * @return bool False if not exists, true if contents were replaced

	 */

	function replace($id, $data, $group = 'default', $expire = '') {

		if (empty ($group))

			$group = 'default';

		if (false === $this->get($id, $group, false))

			return false;

		return $this->set($id, $data, $group, $expire);

	}

	/**

	 * Sets the data contents into the cache

	 *

	 * The cache contents is grouped by the $group parameter followed by the

	 * $id. This allows for duplicate ids in unique groups. Therefore, naming of

	 * the group should be used with care and should follow normal function

	 * naming guidelines outside of core WordPress usage.

	 *

	 * The $expire parameter is not used, because the cache will automatically

	 * expire for each time a page is accessed and PHP finishes. The method is

	 * more for cache plugins which use files.

	 *

	 * @since 2.0.0

	 *

	 * @param int|string $id What to call the contents in the cache

	 * @param mixed $data The contents to store in the cache

	 * @param string $group Where to group the cache contents

	 * @param int $expire Not Used

	 * @return bool Always returns true

	 */

	function set($id, $data, $group = 'default', $expire = '') {

		if (empty ($group))

			$group = 'default';

		if (NULL === $data)

			$data = '';

		if ( is_object($data) )

			$data = wp_clone($data);

		$this->cache[$group][$id] = $data;

		if(isset($this->non_existant_objects[$group][$id]))

			unset ($this->non_existant_objects[$group][$id]);

		return true;

	}

	/**

	 * Echos the stats of the caching.

	 *

	 * Gives the cache hits, and cache misses. Also prints every cached group,

	 * key and the data.

	 *

	 * @since 2.0.0

	 */

	function stats() {

		echo "<p>";

		echo "<strong>Cache Hits:</strong> {$this->cache_hits}<br />";

		echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br />";

		echo "</p>";

		foreach ($this->cache as $group => $cache) {

			echo "<p>";

			echo "<strong>Group:</strong> $group<br />";

			echo "<strong>Cache:</strong>";

			echo "<pre>";

			print_r($cache);

			echo "</pre>";

		}

	}

	/**

	 * PHP4 constructor; Calls PHP 5 style constructor

	 *

	 * @since 2.0.0

	 *

	 * @return WP_Object_Cache

	 */

	function WP_Object_Cache() {

		return $this->__construct();

	}

	/**

	 * Sets up object properties; PHP 5 style constructor

	 *

	 * @since 2.0.8

	 * @return null|WP_Object_Cache If cache is disabled, returns null.

	 */

	function __construct() {

		/**

		 * @todo This should be moved to the PHP4 style constructor, PHP5

		 * already calls __destruct()

		 */

		register_shutdown_function(array(&$this, "__destruct"));

	}

	/**

	 * Will save the object cache before object is completely destroyed.

	 *

	 * Called upon object destruction, which should be when PHP ends.

	 *

	 * @since  2.0.8

	 *

	 * @return bool True value. Won't be used by PHP

	 */

	function __destruct() {

		return true;

	}

}

?>