--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/symfony/src/Symfony/Component/HttpKernel/HttpCache/EsiResponseCacheStrategy.php	Sat Sep 24 15:40:41 2011 +0200
@@ -0,0 +1,74 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * This code is partially based on the Rack-Cache library by Ryan Tomayko,
+ * which is released under the MIT license.
+ * (based on commit 02d2b48d75bcb63cf1c0c7149c077ad256542801)
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpKernel\HttpCache;
+
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * EsiResponseCacheStrategy knows how to compute the Response cache HTTP header
+ * based on the different ESI response cache headers.
+ *
+ * This implementation changes the master response TTL to the smallest TTL received
+ * or force validation if one of the ESI has validation cache strategy.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class EsiResponseCacheStrategy implements EsiResponseCacheStrategyInterface
+{
+    private $cacheable = true;
+    private $ttls = array();
+    private $maxAges = array();
+
+    /**
+     * Adds a Response.
+     *
+     * @param Response $response
+     */
+    public function add(Response $response)
+    {
+        if ($response->isValidateable()) {
+            $this->cacheable = false;
+        } else {
+            $this->ttls[] = $response->getTtl();
+            $this->maxAges[] = $response->getMaxAge();
+        }
+    }
+
+    /**
+     * Updates the Response HTTP headers based on the embedded Responses.
+     *
+     * @param Response $response
+     */
+    public function update(Response $response)
+    {
+        // if we only have one Response, do nothing
+        if (1 === count($this->ttls)) {
+            return;
+        }
+
+        if (!$this->cacheable) {
+            $response->headers->set('Cache-Control', 'no-cache, must-revalidate');
+
+            return;
+        }
+
+        if (null !== $maxAge = min($this->maxAges)) {
+            $response->setSharedMaxAge($maxAge);
+            $response->headers->set('Age', $maxAge - min($this->ttls));
+        }
+        $response->setMaxAge(0);
+    }
+}