Cache.php

<?php
/**
* PPI Cache handler
*
* @package   Cache
* @author    Paul Dragoonis <dragoonis@php.net>
* @license   http://opensource.org/licenses/mit-license.php MIT
* @link      http://www.ppiframework.com
*/
class PPI_Cache {

	/**
	 * Defaults for the handler
	 *
	 * @var array
	 */
    protected $_defaults = array(
        'handler'  => 'disk'
    );

    /**
     * The handler in use
     *
     * @var null|PPI_Cache_Interface
     */
    protected $_handler = null;

	/**
	 * The options to the cache layer. This can be an array of options
	 * or a string of the driver name eg: new PPI_Cache('apc');
	 *
	 * @param array|string $options
	 */
	function __construct(array $options = array()) {

		// We now let you specify the handler as a string for quickness.
		if(is_string($options)) {
			$options = array('handler' => $options);
		}

        if(isset($options['handler'])) {
            // If it's a pre instantiated cache handler then use that
            if(!is_string($options['handler']) && $options['handler'] instanceof PPI_Cache_Interface) {
                $this->_handler = $options['handler'];
                unset($options['handler']);
            }
        }

        $this->_defaults = ($options + $this->_defaults);

        // If no handler was passed in, then we setup that handler now by the string name: i.e: 'disk'
        if($this->_handler === null) {
            $this->setupHandler($this->_defaults['handler']);
        }
	}

	/**
	 * Initialise the cache handler
     *
	 * @param string $handler The handler name
	 * @return void
	 * @throws PPI_Exception
	 */
	function setupHandler($handler) {
		$handler = strtolower($handler);
        $handler = 'PPI_Cache_' . ucfirst($handler);
		$this->_handler = new $handler($this->_defaults);
        if($this->_handler->enabled() === false) {
            throw new PPI_Exception('The cache driver ' . $handler . ' is currently disabled.');
        }
		$this->_handler->init();
	}

    /**
     * Get a key value from the cache
     *
     * @param string $key The Key
     * @return mixed
     */
    function get($key) {
    	return $this->_handler->get($key);
    }

    /**
     * Set a value in the cache
     *
     * @param string $key The Key
     * @param mixed $value The Value
     * @param integer $ttl The TTL
     * @return boolean
     */
    function set($key, $value, $ttl = 0) {
    	return $this->_handler->set($key, $value, $ttl);
    }

    /**
     * Check if a key exists in the cache
     *
     * @param string $key The Key
     * @return boolean
     */
    function exists($key) {
    	return $this->_handler->exists($key);
    }

    /**
     * Remove a value from the cache by key
     *
     * @param string $key The Key
     * @return boolean
     */
    function remove($key) {
    	return $this->_handler->remove($key);
    }

	/**
	 * Get the current registered handler
	 *
	 * @return null|PPI_Cache_Interface
	 */
	function getHandler() {
		return $this->_handler;
	}

	/**
	 * Set the current handler, we check enabled() and exec init() on the handler too to make sure it's ready to go.
	 *
	 * @throws PPI_Exception
	 * @param PPI_Cache_Interface $handler
	 * @return void
	 */
	function setHandler(PPI_Cache_Interface $handler) {
		$this->_handler = $handler;
        if($this->_handler->enabled() === false) {
            throw new PPI_Exception('The cache driver ' . get_class($handler) . ' is currently disabled.');
        }
		$this->_handler->init();
	}

}