use isset in hot path

Author: DavidBadura

src/Guesser/MappedGuesser.php

@@ -24,12 +24,11 @@ public function __construct(private array $map)
     public function guess(ObjectType $type): Normalizer|null
     {
         $className = $type->getClassName();
-        if (! array_key_exists($className, $this->map)) {
+
+        if (!isset($this->map[$className])) {
             return null;
         }
 
-        $normalizerType = $this->map[$className];
-
-        return new $normalizerType();
+        return new $this->map[$className]();
     }
 }

src/MetadataHydrator.php

@@ -111,7 +111,7 @@ public function extract(object $object, array $context = []): mixed
      */
     public function metadata(string $class): ClassMetadata
     {
-        if (array_key_exists($class, $this->classMetadata)) {
+        if (isset($this->classMetadata[$class])) {
             return $this->classMetadata[$class];
         }
 

src/Middleware/TransformMiddleware.php

@@ -95,7 +95,7 @@ public function extract(ClassMetadata $metadata, object $object, array $context,
     {
         $objectId = spl_object_id($object);
 
-        if (array_key_exists($objectId, $this->callStack)) {
+        if (isset($this->callStack[$objectId])) {
             $references = array_values($this->callStack);
             $references[] = $object::class;