diff -r 000000000000 -r 7f95f8617b0b vendor/symfony/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraph.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/symfony/src/Symfony/Component/DependencyInjection/Compiler/ServiceReferenceGraph.php	Sat Sep 24 15:40:41 2011 +0200
@@ -0,0 +1,112 @@
+<?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\DependencyInjection\Compiler;
+
+/**
+ * This is a directed graph of your services.
+ *
+ * This information can be used by your compiler passes instead of collecting
+ * it themselves which improves performance quite a lot.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+class ServiceReferenceGraph
+{
+    private $nodes;
+
+    /**
+     * Constructor.
+     */
+    public function __construct()
+    {
+        $this->nodes = array();
+    }
+
+    /**
+     * Checks if the graph has a specific node.
+     *
+     * @param string $id Id to check
+     */
+    public function hasNode($id)
+    {
+        return isset($this->nodes[$id]);
+    }
+
+    /**
+     * Gets a node by identifier.
+     *
+     * @param string $id The id to retrieve
+     * @return ServiceReferenceGraphNode The node matching the supplied identifier
+     * @throws \InvalidArgumentException
+     */
+    public function getNode($id)
+    {
+        if (!isset($this->nodes[$id])) {
+            throw new \InvalidArgumentException(sprintf('There is no node with id "%s".', $id));
+        }
+
+        return $this->nodes[$id];
+    }
+
+    /**
+     * Returns all nodes.
+     *
+     * @return array An array of all ServiceReferenceGraphNode objects
+     */
+    public function getNodes()
+    {
+        return $this->nodes;
+    }
+
+    /**
+     * Clears all nodes.
+     */
+    public function clear()
+    {
+        $this->nodes = array();
+    }
+
+    /**
+     * Connects 2 nodes together in the Graph.
+     *
+     * @param string $sourceId
+     * @param string $sourceValue
+     * @param string $destId
+     * @param string $destValue
+     * @param string $reference
+     */
+    public function connect($sourceId, $sourceValue, $destId, $destValue = null, $reference = null)
+    {
+        $sourceNode = $this->createNode($sourceId, $sourceValue);
+        $destNode = $this->createNode($destId, $destValue);
+        $edge = new ServiceReferenceGraphEdge($sourceNode, $destNode, $reference);
+
+        $sourceNode->addOutEdge($edge);
+        $destNode->addInEdge($edge);
+    }
+
+    /**
+     * Creates a graph node.
+     *
+     * @param string $id
+     * @param string $value
+     * @return ServiceReferenceGraphNode
+     */
+    private function createNode($id, $value)
+    {
+        if (isset($this->nodes[$id]) && $this->nodes[$id]->getValue() === $value) {
+            return $this->nodes[$id];
+        }
+
+        return $this->nodes[$id] = new ServiceReferenceGraphNode($id, $value);
+    }
+}