--- /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\Exception\ServiceCircularReferenceException;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * Checks your services for circular references.
+ *
+ * References from method calls are ignored since we might be able to resolve
+ * these references depending on the order in which services are called.
+ *
+ * Circular reference from method calls will only be detected at run-time.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+class CheckCircularReferencesPass implements CompilerPassInterface
+{
+ private $currentPath;
+ private $checkedNodes;
+
+ /**
+ * Checks the ContainerBuilder object for circular references.
+ *
+ * @param ContainerBuilder $container The ContainerBuilder instances
+ */
+ public function process(ContainerBuilder $container)
+ {
+ $graph = $container->getCompiler()->getServiceReferenceGraph();
+
+ $this->checkedNodes = array();
+ foreach ($graph->getNodes() as $id => $node) {
+ $this->currentPath = array($id);
+
+ $this->checkOutEdges($node->getOutEdges());
+ }
+ }
+
+ /**
+ * Checks for circular references.
+ *
+ * @param ServiceReferenceGraphEdge[] $edges An array of Edges
+ *
+ * @throws ServiceCircularReferenceException When a circular reference is found.
+ */
+ private function checkOutEdges(array $edges)
+ {
+ foreach ($edges as $edge) {
+ $node = $edge->getDestNode();
+ $id = $node->getId();
+
+ if (empty($this->checkedNodes[$id])) {
+ // don't check circular dependencies for lazy services
+ if (!$node->getValue() || !$node->getValue()->isLazy()) {
+ $searchKey = array_search($id, $this->currentPath);
+ $this->currentPath[] = $id;
+
+ if (false !== $searchKey) {
+ throw new ServiceCircularReferenceException($id, array_slice($this->currentPath, $searchKey));
+ }
+
+ $this->checkOutEdges($node->getOutEdges());
+ }
+
+ $this->checkedNodes[$id] = true;
+ array_pop($this->currentPath);
+ }
+ }
+ }
+}