--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Config\Resource;
+
+/**
+ * ClassExistenceResource represents a class existence.
+ * Freshness is only evaluated against resource existence.
+ *
+ * The resource must be a fully-qualified class name.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class ClassExistenceResource implements SelfCheckingResourceInterface, \Serializable
+{
+ private $resource;
+ private $exists;
+
+ /**
+ * @param string $resource The fully-qualified class name
+ */
+ public function __construct($resource)
+ {
+ $this->resource = $resource;
+ $this->exists = class_exists($resource);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function __toString()
+ {
+ return $this->resource;
+ }
+
+ /**
+ * @return string The file path to the resource
+ */
+ public function getResource()
+ {
+ return $this->resource;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function isFresh($timestamp)
+ {
+ return class_exists($this->resource) === $this->exists;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function serialize()
+ {
+ return serialize(array($this->resource, $this->exists));
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function unserialize($serialized)
+ {
+ list($this->resource, $this->exists) = unserialize($serialized);
+ }
+}