gjerokrsteski/pimf-framework

<?php
/**
 * Util
 *
 * @copyright Copyright (c)  Gjero Krsteski (http://krsteski.de)
 * @license   http://opensource.org/licenses/MIT MIT License
 */

namespace Pimf\Util;

/**
 * The identity map pattern is a database access design pattern used to improve performance
 * by providing a context-specific, in-memory cache to prevent duplicate retrieval of the
 * same object data from the database.
 *
 * @package Util
 * @author  Gjero Krsteski <gjero@krsteski.de>
 */
class IdentityMap
{
    /**
     * @var \ArrayObject
     */
    protected $idToObject;

    /**
     * @var \SplObjectStorage
     */
    protected $objectToId;

    public function __construct()
    {
        $this->objectToId = new \SplObjectStorage();
        $this->idToObject = new \ArrayObject();
    }

    /**
     * @param integer $key
     * @param mixed   $object
     */
    public function set($key, $object)
    {
        $this->idToObject[$key] = $object;
        $this->objectToId[$object] = $key;
    }

    /**
     * @param mixed $object
     *
     * @throws \OutOfBoundsException
     * @return integer
     */
    public function getId($object)
    {
        if (false === $this->hasObject($object)) {
            throw new \OutOfBoundsException('no object=' . get_class($object) . ' at the identity-map');
        }

        return $this->objectToId[$object];
    }

    /**
     * @param integer $key
     *
     * @return boolean
     */
    public function hasId($key)
    {
        return isset($this->idToObject[$key]);
    }

    /**
     * @param mixed $object
     *
     * @return boolean
     */
    public function hasObject($object)
    {
        return isset($this->objectToId[$object]);
    }

    /**
     * @param integer $key
     *
     * @throws \OutOfBoundsException
     * @return object
     */
    public function getObject($key)
    {
        if (false === $this->hasId($key)) {
            throw new \OutOfBoundsException('no id=' . $key . ' at the identity-map');
        }

        return $this->idToObject[$key];
    }
}