recursivity check

src/Analyze/EntityAnalyzer.php

@@ -37,6 +37,8 @@ readonly class EntityAnalyzer
      */
     public function analyze(): EntityResult
     {
+        (new RecursionCheck($this->entity))->check();
+
         $refClass = new ReflectionClass($this->entity);
 
         $fields = $this->fields($refClass);

src/Analyze/RecursionCheck.php

@@ -0,0 +1,74 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kartierung\Analyze;
+
+use Kartierung\Analyze\Exception\InvalidEntity;
+use Kartierung\Attribute\ListOf;
+use ReflectionClass;
+use ReflectionException;
+
+readonly class RecursionCheck
+{
+    /**
+     * @param class-string<object> $fqcn
+     */
+    public function __construct(
+        private string $fqcn
+    ) {}
+
+    public function check(): void
+    {
+        /** @var list<class-string<object>> $seenClasses */
+        $seenClasses = [$this->fqcn];
+        $toProcess = [...$this->declaredListTypes($this->fqcn)];
+
+        while (!empty($toProcess)) {
+            $current = array_pop($toProcess);
+
+            try {
+                // is there a better workaround?
+                new ReflectionClass($current);
+
+                if (in_array($current, $seenClasses)) {
+                    throw new InvalidEntity(
+                        "Entity $this->fqcn declares a recursive mapping. This is not supported."
+                    );
+                }
+
+                $seenClasses[] = $current;
+            } catch (ReflectionException) {
+                // $current does not reference a class, skip
+            }
+        }
+    }
+
+    /**
+     * @param class-string<object> $fqcn
+     * @return list<class-string<object>>
+     */
+    private function declaredListTypes(string $fqcn): array
+    {
+        $params = (new ReflectionClass($fqcn))->getConstructor()?->getParameters();
+
+        if ($params === null) {
+            return [];
+        }
+
+        $result = [];
+
+        foreach ($params as $param) {
+            $listAttr = $param->getAttributes(ListOf::class);
+            if (empty($listAttr)) {
+                continue;
+            }
+
+            /** @var ListOf $inst */
+            $inst = $listAttr[0]->newInstance();
+            $result[] = $inst->entitiyFqcn;
+        }
+
+        return $result;
+    }
+}

tests/Analyze/EntityAnalyzerTest.php

@@ -168,4 +168,17 @@ class EntityAnalyzerTest extends TestCase
             $result->fields[1]
         );
     }
+
+    public function testInfiniteRecursionIsDetected(): void
+    {
+        // Given
+        $entity = EntityWithInfiniteRecursion::class;
+
+        // Then
+        $this->expectException(InvalidEntity::class);
+        $this->expectExceptionMessageMatches('/.*recursive.*/');
+
+        // When
+        (new EntityAnalyzer($entity))->analyze();
+    }
 }

tests/Analyze/EntityWithInfiniteRecursion.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kartierung\Analyze;
+
+use Kartierung\Attribute\Id;
+use Kartierung\Attribute\ListOf;
+
+class EntityWithInfiniteRecursion
+{
+    public function __construct(
+        #[Id]
+        public int $id,
+        #[ListOf(self::class)]
+        public array $children
+    ) {}
+}