--- /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\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Alias;
+
+/**
+ * Represents a node in your service graph.
+ *
+ * Value is typically a definition, or an alias.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+class ServiceReferenceGraphNode
+{
+ private $id;
+ private $inEdges = array();
+ private $outEdges = array();
+ private $value;
+
+ /**
+ * @param string $id The node identifier
+ * @param mixed $value The node value
+ */
+ public function __construct($id, $value)
+ {
+ $this->id = $id;
+ $this->value = $value;
+ }
+
+ /**
+ * Adds an in edge to this node.
+ *
+ * @param ServiceReferenceGraphEdge $edge
+ */
+ public function addInEdge(ServiceReferenceGraphEdge $edge)
+ {
+ $this->inEdges[] = $edge;
+ }
+
+ /**
+ * Adds an out edge to this node.
+ *
+ * @param ServiceReferenceGraphEdge $edge
+ */
+ public function addOutEdge(ServiceReferenceGraphEdge $edge)
+ {
+ $this->outEdges[] = $edge;
+ }
+
+ /**
+ * Checks if the value of this node is an Alias.
+ *
+ * @return bool True if the value is an Alias instance
+ */
+ public function isAlias()
+ {
+ return $this->value instanceof Alias;
+ }
+
+ /**
+ * Checks if the value of this node is a Definition.
+ *
+ * @return bool True if the value is a Definition instance
+ */
+ public function isDefinition()
+ {
+ return $this->value instanceof Definition;
+ }
+
+ /**
+ * Returns the identifier.
+ *
+ * @return string
+ */
+ public function getId()
+ {
+ return $this->id;
+ }
+
+ /**
+ * Returns the in edges.
+ *
+ * @return array The in ServiceReferenceGraphEdge array
+ */
+ public function getInEdges()
+ {
+ return $this->inEdges;
+ }
+
+ /**
+ * Returns the out edges.
+ *
+ * @return array The out ServiceReferenceGraphEdge array
+ */
+ public function getOutEdges()
+ {
+ return $this->outEdges;
+ }
+
+ /**
+ * Returns the value of this Node.
+ *
+ * @return mixed The value
+ */
+ public function getValue()
+ {
+ return $this->value;
+ }
+}