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vendor/symfony/dependency-injection/Compiler/CheckCircularReferencesPass.php

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+<?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\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
+
+/**
+ * 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 array $currentPath;
+    private array $checkedNodes;
+    private array $checkedLazyNodes;
+
+    /**
+     * Checks the ContainerBuilder object for circular references.
+     */
+    public function process(ContainerBuilder $container): void
+    {
+        $graph = $container->getCompiler()->getServiceReferenceGraph();
+
+        $this->checkedNodes = [];
+        foreach ($graph->getNodes() as $id => $node) {
+            $this->currentPath = [$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 $edges): void
+    {
+        foreach ($edges as $edge) {
+            $node = $edge->getDestNode();
+            $id = $node->getId();
+
+            if (!empty($this->checkedNodes[$id])) {
+                continue;
+            }
+
+            $isLeaf = (bool) $node->getValue();
+            $isConcrete = !$edge->isLazy() && !$edge->isWeak();
+
+            // Skip already checked lazy services if they are still lazy. Will not gain any new information.
+            if (!empty($this->checkedLazyNodes[$id]) && (!$isLeaf || !$isConcrete)) {
+                continue;
+            }
+
+            // Process concrete references, otherwise defer check circular references for lazy edges.
+            if (!$isLeaf || $isConcrete) {
+                $searchKey = array_search($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;
+                unset($this->checkedLazyNodes[$id]);
+            } else {
+                $this->checkedLazyNodes[$id] = true;
+            }
+
+            array_pop($this->currentPath);
+        }
+    }
+}