Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/http-foundation/RequestStack.php

@@ -0,0 +1,103 @@
+<?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\HttpFoundation;
+
+/**
+ * Request stack that controls the lifecycle of requests.
+ *
+ * @author Benjamin Eberlei <kontakt@beberlei.de>
+ */
+class RequestStack
+{
+    /**
+     * @var Request[]
+     */
+    private $requests = array();
+
+    /**
+     * Pushes a Request on the stack.
+     *
+     * This method should generally not be called directly as the stack
+     * management should be taken care of by the application itself.
+     */
+    public function push(Request $request)
+    {
+        $this->requests[] = $request;
+    }
+
+    /**
+     * Pops the current request from the stack.
+     *
+     * This operation lets the current request go out of scope.
+     *
+     * This method should generally not be called directly as the stack
+     * management should be taken care of by the application itself.
+     *
+     * @return Request|null
+     */
+    public function pop()
+    {
+        if (!$this->requests) {
+            return;
+        }
+
+        return array_pop($this->requests);
+    }
+
+    /**
+     * @return Request|null
+     */
+    public function getCurrentRequest()
+    {
+        return end($this->requests) ?: null;
+    }
+
+    /**
+     * Gets the master Request.
+     *
+     * Be warned that making your code aware of the master request
+     * might make it un-compatible with other features of your framework
+     * like ESI support.
+     *
+     * @return Request|null
+     */
+    public function getMasterRequest()
+    {
+        if (!$this->requests) {
+            return;
+        }
+
+        return $this->requests[0];
+    }
+
+    /**
+     * Returns the parent request of the current.
+     *
+     * Be warned that making your code aware of the parent request
+     * might make it un-compatible with other features of your framework
+     * like ESI support.
+     *
+     * If current Request is the master request, it returns null.
+     *
+     * @return Request|null
+     */
+    public function getParentRequest()
+    {
+        $pos = count($this->requests) - 2;
+
+        if (!isset($this->requests[$pos])) {
+            return;
+        }
+
+        return $this->requests[$pos];
+    }
+}