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<?php
/*
* $Horde: horde/lib/Cache.php,v 1.2.2.7 2003/04/28 19:59:06 jan Exp $
*
* Copyright 1999-2003 Anil Madhavapeddy <anil@recoil.org>
*
* See the enclosed file COPYING for license information (LGPL). If you
* did not receive this file, see http://www.fsf.org/copyleft/lgpl.html.
*/
/** @constant CACHE_IMS If Modified Since Cache request */
define('CACHE_IMS', -1);
/**
* The Cache:: class provides a common abstracted interface into the
* various caching backends. It also provides functions for checking
* in, retrieving, and flushing a cache.
*
* @author Anil Madhavapeddy <anil@recoil.org>
* @version $Revision: 1.2.2.7 $
* @since Horde 1.3
* @package horde.cache
*/
class Cache {
/**
* Attempts to return a concrete Cache instance based on $driver.
*
* @param mixed $driver The type of concrete Cache subclass to return.
* This is based on the storage driver ($driver). The
* code is dynamically included. If $driver is an array,
* then we will look in $driver[0]/lib/Cache/ for
* the subclass implementation named $driver[1].php.
* @param array $params (optional) A hash containing any additional
* configuration or connection parameters a
* subclass might need.
*
* @return object Cache The newly created concrete Cache instance, or
* false on error.
*/
function &factory($driver, $params = array())
{
if (is_array($driver)) {
list($app, $driver) = $driver;
}
/* Return a base Cache object if no driver is specified. */
$driver = strtolower(basename($driver));
if (empty($driver) || (strcmp($driver, 'none') == 0)) {
return new Cache;
}
if (!empty($app)) {
include_once $GLOBALS['registry']->getParam('fileroot', $app) . '/lib/Cache/' . $driver . '.php';
} elseif (@file_exists(dirname(__FILE__) . '/Cache/' . $driver . '.php')) {
include_once dirname(__FILE__) . '/Cache/' . $driver . '.php';
} else {
@include_once 'Horde/Cache/' . $driver . '.php';
}
$class = 'Cache_' . $driver;
if (class_exists($class)) {
return new $class($params);
} else {
return PEAR::raiseError('Class definition of ' . $class . ' not found.');
}
}
/**
* Attempts to return a reference to a concrete Cache instance
* based on $driver. It will only create a new instance if no
* Cache instance with the same parameters currently exists.
*
* This should be used if multiple cache backends (and, thus,
* multiple Cache instances) are required.
*
* This method must be invoked as: $var = &Cache::singleton()
*
* @param mixed $driver The type of concrete Cache subclass to return.
* This is based on the storage driver ($driver). The
* code is dynamically included. If $driver is an array,
* then we will look in $driver[0]/lib/Cache/ for
* the subclass implementation named $driver[1].php.
* @param array $params (optional) A hash containing any additional
* configuration or connection parameters a subclass
* might need.
*
* @return object Cache The concrete Cache reference, or false on an error.
*
* @since Horde 2.2
*/
function &singleton($driver, $params = array())
{
static $instances;
if (!isset($instances)) {
$instances = array();
}
if (is_array($driver)) {
$drivertag = implode(':', $driver);
} else {
$drivertag = $driver;
}
$signature = md5(strtolower($drivertag) . '][' . @implode('][', $params));
if (!isset($instances[$signature])) {
$instances[$signature] = &Cache::factory($driver, $params);
}
return $instances[$signature];
}
/**
* Attempts to store an object in the cache.
*
* @param string $oid Object ID used as the caching key.
* @param mixed $data Data to store in the cache.
* @return boolean True on success, false on failure.
*/
function store($oid, &$data)
{
return true;
}
/**
* Attempts to retrieve a cached object.
*
* @param string $oid Object ID to query.
* @param enum $type Expiration heuristic.
* CACHE_IMS: Expire if supplied value is greater than
* cached time
* @param int $val Value to supply for the expiration heuristic.
* @return mixed Cached data, or false if none was found.
*/
function query($oid, $type = CACHE_IMS, $val = 0)
{
return false;
}
}
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