Freezer.php

<?php
require_once 'Object/Freezer/HashGenerator/NonRecursiveSHA1.php';
require_once 'Object/Freezer/IdGenerator/UUID.php';
require_once 'Object/Freezer/Util.php';

class Object_Freezer
{
    protected $autoload = TRUE;

    protected $blacklist = array();

    protected $idGenerator;

    protected $hashGenerator;

    public function __construct(Object_Freezer_IdGenerator $idGenerator = NULL, Object_Freezer_HashGenerator $hashGenerator = NULL, array $blacklist = array(), $useAutoload = TRUE)
    {
        // Use Object_Freezer_IdGenerator_UUID by default.
        if ($idGenerator === NULL) {
            $idGenerator = new Object_Freezer_IdGenerator_UUID;
        }

        // Use Object_Freezer_HashGenerator_NonRecursiveSHA1 by default.
        if ($hashGenerator === NULL) {
            $hashGenerator = new Object_Freezer_HashGenerator_NonRecursiveSHA1(
              $idGenerator
            );
        }

        $this->setIdGenerator($idGenerator);
        $this->setHashGenerator($hashGenerator);
        $this->setBlacklist($blacklist);
        $this->setUseAutoload($useAutoload);
    }

    public function freeze($object, array &$objects = array())
    {
        // Bail out if a non-object was passed.
        if (!is_object($object)) {
            throw Object_Freezer_Util::getInvalidArgumentException(1, 'object');
        }

        // The object has not been frozen before, generate a new UUID and
        // store it in the "special" __php_object_freezer_uuid attribute.
        if (!isset($object->__php_object_freezer_uuid)) {
            $object->__php_object_freezer_uuid = $this->idGenerator->getId();
        }

        $isDirty = $this->isDirty($object, TRUE);

        if (!isset($objects[$object->__php_object_freezer_uuid])) {
            $objects[$object->__php_object_freezer_uuid] = array(
              'className' => get_class($object),
              'isDirty'   => $isDirty,
              'state'     => array()
            );

            // Iterate over the attributes of the object.
            foreach (Object_Freezer_Util::readAttributes($object) as $name => $value) {
                if ($name !== '__php_object_freezer_uuid') {
                    if (is_array($value)) {
                        $this->freezeArray($value, $objects);
                    }

                    else if (is_object($value) &&
                             !in_array(get_class($object), $this->blacklist)) {
                        // Freeze the aggregated object.
                        $this->freeze($value, $objects);

                        // Replace $value with the aggregated object's UUID.
                        $value = '__php_object_freezer_' . $value->__php_object_freezer_uuid;
                    }

                    else if (is_resource($value)) {
                        $value = NULL;
                    }

                    // Store the attribute in the object's state array.
                    $objects[$object->__php_object_freezer_uuid]['state'][$name] = $value;
                }
            }
        }

        return array(
          'root'    => $object->__php_object_freezer_uuid,
          'objects' => $objects
        );
    }

    protected function freezeArray(array &$array, array &$objects)
    {
        foreach ($array as &$value) {
            if (is_array($value)) {
                $this->freezeArray($value, $objects);
            }

            else if (is_object($value)) {
                $tmp   = $this->freeze($value, $objects);
                $value = '__php_object_freezer_' . $tmp['root'];
                unset($tmp);
            }
        }
    }

    public function thaw(array $frozenObject, $root = NULL, array &$objects = array())
    {
        // Bail out if one of the required classes cannot be found.
        foreach ($frozenObject['objects'] as $_frozenObject) {
            if (!class_exists($_frozenObject['className'], $this->useAutoload)) {
                throw new RuntimeException(
                  sprintf(
                    'Class "%s" could not be found.', $_frozenObject['className']
                  )
                );
            }
        }

        // By default, we thaw the root object and (recursively)
        // its aggregated objects.
        if ($root === NULL) {
            $root = $frozenObject['root'];
        }

        // Thaw object (if it has not been thawed before).
        if (!isset($objects[$root])) {
            $className = $frozenObject['objects'][$root]['className'];
            $state     = $frozenObject['objects'][$root]['state'];

            // Use a trick to create a new object of a class
            // without invoking its constructor.
            $objects[$root] = unserialize(
              sprintf('O:%d:"%s":0:{}', strlen($className), $className)
            );

            // Handle aggregated objects.
            $this->thawArray($state, $frozenObject, $objects);

            $reflector = new ReflectionObject($objects[$root]);

            foreach ($state as $name => $value) {
                if (strpos($name, '__php_object_freezer') !== 0) {
                    $attribute = $reflector->getProperty($name);
                    $attribute->setAccessible(TRUE);
                    $attribute->setValue($objects[$root], $value);
                }
            }

            // Store UUID.
            $objects[$root]->__php_object_freezer_uuid = $root;

            // Store hash.
            if (isset($state['__php_object_freezer_hash'])) {
                $objects[$root]->__php_object_freezer_hash = $state['__php_object_freezer_hash'];
            }
        }

        return $objects[$root];
    }

    protected function thawArray(array &$array, array $frozenObject, array &$objects)
    {
        foreach ($array as &$value) {
            if (is_array($value)) {
                $this->thawArray($value, $frozenObject, $objects);
            }

            else if (is_string($value) && strpos($value, '__php_object_freezer') === 0) {
                $aggregatedObjectId = str_replace(
                  '__php_object_freezer_', '', $value
                );

                if (isset($frozenObject['objects'][$aggregatedObjectId])) {
                    $value = $this->thaw(
                      $frozenObject, $aggregatedObjectId, $objects
                    );
                }
            }
        }
    }

    public function getIdGenerator()
    {
        return $this->idGenerator;
    }

    public function setIdGenerator(Object_Freezer_IdGenerator $idGenerator)
    {
        $this->idGenerator = $idGenerator;
    }

    public function getHashGenerator()
    {
        return $this->hashGenerator;
    }

    public function setHashGenerator(Object_Freezer_HashGenerator $hashGenerator)
    {
        $this->hashGenerator = $hashGenerator;
    }

    public function getBlacklist()
    {
        return $this->blacklist;
    }

    public function setBlacklist(array $blacklist)
    {
        $this->blacklist = $blacklist;
    }

    public function getUseAutoload()
    {
        return $this->useAutoload;
    }

    public function setUseAutoload($flag)
    {
        // Bail out if a non-boolean was passed.
        if (!is_bool($flag)) {
            throw Object_Freezer_Util::getInvalidArgumentException(1, 'boolean');
        }

        $this->useAutoload = $flag;
    }

    public function isDirty($object, $rehash = FALSE)
    {
        // Bail out if a non-object was passed.
        if (!is_object($object)) {
            throw Object_Freezer_Util::getInvalidArgumentException(1, 'object');
        }

        // Bail out if a non-boolean was passed.
        if (!is_bool($rehash)) {
            throw Object_Freezer_Util::getInvalidArgumentException(2, 'boolean');
        }

        $isDirty = TRUE;
        $hash    = $this->hashGenerator->getHash($object);

        if (isset($object->__php_object_freezer_hash) &&
            $object->__php_object_freezer_hash == $hash) {
            $isDirty = FALSE;
        }

        if ($isDirty && $rehash) {
            $object->__php_object_freezer_hash = $hash;
        }

        return $isDirty;
    }
}

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