[task/acm-refactor] Refactor the ACM classes to have a common interface.

They are now refered to as cache drivers rather than ACM classes. The
additional utility functions from the original cache class have been
moved to the cache_service. The class loader is now instantiated without
a cache instance and passed one as soon as it is constructed to allow
autoloading the cache classes.

PHPBB3-9983

phpBB/includes/cache/factory.php

@@ -0,0 +1,52 @@
+<?php
+/**
+*
+* @package acm
+* @version $Id$
+* @copyright (c) 2010 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* @package acm
+*/
+class phpbb_cache_factory
+{
+	private $acm_type;
+	
+	public function __construct($acm_type)
+	{
+		$this->acm_type = $acm_type;
+	}
+	
+	public function get_acm()
+	{
+		$class_name = 'phpbb_cache_driver_' . $this->acm_type;
+		return new $class_name();
+	}
+	
+	public function get_service()
+	{
+		$acm = $this->get_acm();
+		$service = new phpbb_cache_service($acm);
+		return $service;
+	}
+	
+	/**
+	* for convenience to allow:
+	* $cache = phpbb_cache_factory::create('file')->get_service();
+	*/
+	public static function create($acm_type)
+	{
+		return new self($acm_type);
+	}
+}