Index AST nodes by class name for O(1) getNodeByClassName lookups

getNodeByClassName() did two linear scans over every node (one by class
name, one by alias) on each call. The schema builder/resolvers call it
once per referenced type while resolving fields, so on a non-trivial
schema this becomes a hot path: for one real schema (253 nodes) a single
request triggered ~3,300 calls, i.e. hundreds of thousands of
getClassName() comparisons, dominating the request in a profiler.

Build a class-name and an alias index once in the constructor (the Ast
is immutable) and resolve lookups from them. The class-name-before-alias
resolution order is preserved.

Author: adri

src/Ast.php

@@ -25,9 +25,35 @@
      */
     private array $nodes;
 
+    /**
+     * Index of nodes by class name, with aliases as a fallback, for O(1) lookups in getNodeByClassName().
+     *
+     * @var array<class-string, Node>
+     */
+    private array $nodesByName;
+
     public function __construct(Node ...$nodes)
     {
         $this->nodes = array_values($nodes);
+
+        // Index class names first so they take precedence over aliases.
+        $nodesByName = [];
+
+        foreach ($this->nodes as $node) {
+            $nodesByName[$node->getClassName()] ??= $node;
+        }
+
+        foreach ($this->nodes as $node) {
+            if ($node instanceof AliasedNode) {
+                $alias = $node->getAlias();
+
+                if ($alias !== null) {
+                    $nodesByName[$alias] ??= $node;
+                }
+            }
+        }
+
+        $this->nodesByName = $nodesByName;
     }
 
     /**
@@ -47,28 +73,7 @@ public function getNodesByNodeType(string $nodeType): array
      */
     public function getNodeByClassName(string $className): ?Node
     {
-        foreach ($this->nodes as $node) {
-            if ($node->getClassName() !== $className) {
-                continue;
-            }
-
-            return $node;
-        }
-
-        // Try to retrieve node by alias
-        foreach ($this->nodes as $node) {
-            if (!$node instanceof AliasedNode) {
-                continue;
-            }
-
-            if ($node->getAlias() !== $className) {
-                continue;
-            }
-
-            return $node;
-        }
-
-        return null;
+        return $this->nodesByName[$className] ?? null;
     }
 
     /**

tests/AstTest.php

@@ -12,6 +12,7 @@
 use Jerowork\GraphqlAttributeSchema\Node\InterfaceTypeNode;
 use Jerowork\GraphqlAttributeSchema\Node\MutationNode;
 use Jerowork\GraphqlAttributeSchema\Node\QueryNode;
+use Jerowork\GraphqlAttributeSchema\Node\ScalarNode;
 use Jerowork\GraphqlAttributeSchema\Node\TypeNode;
 use Jerowork\GraphqlAttributeSchema\Node\TypeReference\ObjectTypeReference;
 use Jerowork\GraphqlAttributeSchema\Node\TypeReference\ScalarTypeReference;
@@ -22,6 +23,7 @@
 use Jerowork\GraphqlAttributeSchema\Test\Doubles\InterfaceType\TestOtherInterfaceType;
 use Jerowork\GraphqlAttributeSchema\Test\Doubles\Mutation\TestMutation;
 use Jerowork\GraphqlAttributeSchema\Test\Doubles\Query\TestQuery;
+use Jerowork\GraphqlAttributeSchema\Test\Doubles\Scalar\TestScalarType;
 use Jerowork\GraphqlAttributeSchema\Test\Doubles\Type\Loader\TestTypeLoader;
 use Jerowork\GraphqlAttributeSchema\Test\Doubles\Type\TestType;
 use Override;
@@ -104,6 +106,46 @@ public function itShouldGetNodeByTypeId(): void
     {
         self::assertSame($this->typeNode, $this->ast->getNodeByClassName(TestType::class));
         self::assertSame($this->enumNode2, $this->ast->getNodeByClassName(TestAnotherEnumType::class));
+        self::assertNull($this->ast->getNodeByClassName(TestQuery::class));
+    }
+
+    #[Test]
+    public function itShouldGetNodeByAliasWhenThereIsNoClassNameMatch(): void
+    {
+        $ast = new Ast(
+            $scalarNode = new ScalarNode(
+                TestScalarType::class,
+                'TestScalar',
+                null,
+                TestAnotherEnumType::class,
+            ),
+        );
+
+        self::assertSame($scalarNode, $ast->getNodeByClassName(TestScalarType::class));
+        self::assertSame($scalarNode, $ast->getNodeByClassName(TestAnotherEnumType::class));
+    }
+
+    #[Test]
+    public function itShouldPreferAClassNameMatchOverAnAliasMatch(): void
+    {
+        $ast = new Ast(
+            new ScalarNode(
+                TestScalarType::class,
+                'TestScalar',
+                null,
+                TestType::class,
+            ),
+            $typeNode = new TypeNode(
+                TestType::class,
+                'type',
+                null,
+                [],
+                null,
+                [],
+            ),
+        );
+
+        self::assertSame($typeNode, $ast->getNodeByClassName(TestType::class));
     }
 
     #[Test]