Watch for changes in objects

ObjectChangedWatcher.php

<?php

namespace Reddin\Bundle\MEPBundle\Service;

class ObjectChangedWatcher
{
    /**
     * @var array
     */
    private $objects;

    public function __construct()
    {
        $this->objects = array();
    }

    /**
     * @param object $object
     * @return $this
     */
    public function watch($object)
    {
        if (!$this->isWatched($object)) {
            $this->pushObjectToStorage($object);
        }

        return $this;
    }

    /**
     * @param object|null $object
     * @return $this
     */
    public function clear($object = null)
    {
        $objectHash = $this->getObjectHash($object);
        unset ($this->objects[$objectHash]);

        return $this;
    }

    /**
     * @param object|null $object
     * @return $this
     * @throws \Exception
     */
    public function reset($object = null)
    {
        if ($object) {
            if (!$this->isWatched($object)) {
                throw new \Exception('Trying to reset non-watched object.');
            }

            $this->pushObjectToStorage($object);
        } else {
            foreach ($this->objects as &$objectInfo) {
                $objectInfo['stamp'] = $this->getObjectStamp($objectInfo['object']);
            }
        }

        return $this;
    }

    /**
     * @param object $object
     * @return bool
     */
    public function isWatched($object)
    {
        return ($this->findObjectInfo($object) === null) ? false : true;
    }

    /**
     * @param object $object
     * @return bool
     * @throws \Exception
     */
    public function isChanged($object)
    {
        if (!$this->isWatched($object)) {
            throw new \Exception('Can\'t get state of non-watched object.');
        }

        $objectInfo = $this->findObjectInfo($object);
        $currentStamp = $this->getObjectStamp($object);

        return ($currentStamp !== $objectInfo['stamp']);
    }

    /**
     * @param string|null $className
     * @return array
     */
    public function getChanged($className = null)
    {
        $changedObjects = array();

        foreach ($this->objects as $objectInfo) {
            $object = $objectInfo['object'];
            $currentStamp = $this->getObjectStamp($object);

            if ($className && (!is_a($object, $className))) continue;

            if ($currentStamp !== $objectInfo['stamp']) {
                $changedObjects[] = $object;
            }
        }

        return $changedObjects;
    }

    /**
     * @param object $object
     * @return string
     */
    private function pushObjectToStorage($object)
    {
        $objectHash = $this->getObjectHash($object);
        $objectStamp = $this->getObjectStamp($object);

        $this->objects[$objectHash] = array(
            'object' => $object,
            'stamp' => $objectStamp
        );

        return $objectHash;
    }

    /**
     * @param object $object
     * @return array|null
     */
    private function findObjectInfo($object)
    {
        $objectHash = $this->getObjectHash($object);

        return isset($this->objects[$objectHash]) ? $this->objects[$objectHash] : null;
    }

    /**
     * @param object $object
     * @return string
     */
    private function getObjectHash($object)
    {
        return spl_object_hash($object);
    }

    /**
     * @param object $object
     * @return string
     */
    private function getObjectStamp($object)
    {
        return md5(serialize($object));
    }
}