From 70004b622c638b8f422fcb3ec7843634ac27101a Mon Sep 17 00:00:00 2001
From: David Badura <david.badura@patchlevel.de>
Date: Thu, 26 Feb 2026 11:50:11 +0100
Subject: [PATCH 1/5] clone stack

---
 src/MetadataHydrator.php | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/MetadataHydrator.php b/src/MetadataHydrator.php
index afc507f..93badc4 100644
--- a/src/MetadataHydrator.php
+++ b/src/MetadataHydrator.php
@@ -24,12 +24,15 @@ final class MetadataHydrator implements Hydrator
     /** @var array<class-string, ClassMetadata> */
     private array $classMetadata = [];
 
+    private readonly Stack $stack;
+
     /** @param list<Middleware> $middlewares */
     public function __construct(
         private readonly MetadataFactory $metadataFactory = new AttributeMetadataFactory(),
         private readonly array $middlewares = [new TransformMiddleware()],
         private readonly bool $defaultLazy = false,
     ) {
+        $this->stack = new Stack($this->middlewares);
     }
 
     /**
@@ -63,7 +66,7 @@ public function hydrate(string $class, mixed $data, array $context = []): object
         }
 
         if (PHP_VERSION_ID < 80400) {
-            $stack = new Stack($this->middlewares);
+            $stack = clone $this->stack;
 
             return $stack->next()->hydrate($metadata, $data, $context, $stack);
         }
@@ -71,14 +74,14 @@ public function hydrate(string $class, mixed $data, array $context = []): object
         $lazy = $metadata->lazy ?? $this->defaultLazy;
 
         if (!$lazy) {
-            $stack = new Stack($this->middlewares);
+            $stack = clone $this->stack;
 
             return $stack->next()->hydrate($metadata, $data, $context, $stack);
         }
 
         return (new ReflectionClass($class))->newLazyProxy(
             function () use ($metadata, $data, $context): object {
-                $stack = new Stack($this->middlewares);
+                $stack = clone $this->stack;
 
                 return $stack->next()->hydrate($metadata, $data, $context, $stack);
             },
@@ -94,7 +97,7 @@ public function extract(object $object, array $context = []): mixed
             return $metadata->normalizer->normalize($object, $context);
         }
 
-        $stack = new Stack($this->middlewares);
+        $stack = clone $this->stack;
 
         return $stack->next()->extract($metadata, $object, $context, $stack);
     }

From bcdad75d74fb34db9a91b64efe3a77f89f5f4f6c Mon Sep 17 00:00:00 2001
From: David Badura <david.badura@patchlevel.de>
Date: Thu, 26 Feb 2026 11:51:44 +0100
Subject: [PATCH 2/5] improve stack performance

---
 src/Middleware/Stack.php | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/src/Middleware/Stack.php b/src/Middleware/Stack.php
index 7a47f62..3cba48d 100644
--- a/src/Middleware/Stack.php
+++ b/src/Middleware/Stack.php
@@ -16,14 +16,6 @@ public function __construct(
 
     public function next(): Middleware
     {
-        $next = $this->middlewares[$this->index] ?? null;
-
-        if ($next === null) {
-            throw new NoMoreMiddleware();
-        }
-
-        $this->index++;
-
-        return $next;
+        return $this->middlewares[$this->index++] ?? throw new NoMoreMiddleware();
     }
 }

From 6fe3412d3c644b69244bb27a460e5670785939c4 Mon Sep 17 00:00:00 2001
From: David Badura <david.badura@patchlevel.de>
Date: Thu, 26 Feb 2026 11:58:24 +0100
Subject: [PATCH 3/5] early return first

---
 src/Normalizer/ObjectMapNormalizer.php | 16 ++++++++--------
 src/Normalizer/ObjectNormalizer.php    | 16 ++++++++--------
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/Normalizer/ObjectMapNormalizer.php b/src/Normalizer/ObjectMapNormalizer.php
index 1f99571..7a2ff62 100644
--- a/src/Normalizer/ObjectMapNormalizer.php
+++ b/src/Normalizer/ObjectMapNormalizer.php
@@ -44,14 +44,14 @@ public function setHydrator(Hydrator $hydrator): void
      */
     public function normalize(mixed $value, array $context): mixed
     {
-        if (!$this->hydrator) {
-            throw new MissingHydrator();
-        }
-
         if ($value === null) {
             return null;
         }
 
+        if (!$this->hydrator) {
+            throw new MissingHydrator();
+        }
+
         if (!is_object($value)) {
             throw InvalidArgument::withWrongType(
                 sprintf('%s|null', implode('|', array_keys($this->classToTypeMap))),
@@ -84,14 +84,14 @@ public function normalize(mixed $value, array $context): mixed
      */
     public function denormalize(mixed $value, array $context): mixed
     {
-        if (!$this->hydrator) {
-            throw new MissingHydrator();
-        }
-
         if ($value === null) {
             return null;
         }
 
+        if (!$this->hydrator) {
+            throw new MissingHydrator();
+        }
+
         if (!is_array($value)) {
             throw InvalidArgument::withWrongType('array<string, mixed>|null', $value);
         }
diff --git a/src/Normalizer/ObjectNormalizer.php b/src/Normalizer/ObjectNormalizer.php
index f97d213..6117f2d 100644
--- a/src/Normalizer/ObjectNormalizer.php
+++ b/src/Normalizer/ObjectNormalizer.php
@@ -26,14 +26,14 @@ public function __construct(
     /** @param array<string, mixed> $context */
     public function normalize(mixed $value, array $context): mixed
     {
-        if (!$this->hydrator) {
-            throw new MissingHydrator();
-        }
-
         if ($value === null) {
             return null;
         }
 
+        if (!$this->hydrator) {
+            throw new MissingHydrator();
+        }
+
         $className = $this->getClassName();
 
         if (!$value instanceof $className) {
@@ -46,14 +46,14 @@ public function normalize(mixed $value, array $context): mixed
     /** @param array<string, mixed> $context */
     public function denormalize(mixed $value, array $context): object|null
     {
-        if (!$this->hydrator) {
-            throw new MissingHydrator();
-        }
-
         if ($value === null) {
             return null;
         }
 
+        if (!$this->hydrator) {
+            throw new MissingHydrator();
+        }
+
         $className = $this->getClassName();
 
         return $this->hydrator->hydrate($className, $value, $context);

From 52a4717ad167e18824bb5a254de863bab8275209 Mon Sep 17 00:00:00 2001
From: David Badura <david.badura@patchlevel.de>
Date: Thu, 26 Feb 2026 12:05:19 +0100
Subject: [PATCH 4/5] use isset in hot path

---
 src/Guesser/MappedGuesser.php          | 7 +++----
 src/MetadataHydrator.php               | 2 +-
 src/Middleware/TransformMiddleware.php | 2 +-
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/Guesser/MappedGuesser.php b/src/Guesser/MappedGuesser.php
index a36875e..7169d1c 100644
--- a/src/Guesser/MappedGuesser.php
+++ b/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]();
     }
 }
diff --git a/src/MetadataHydrator.php b/src/MetadataHydrator.php
index 93badc4..af95bda 100644
--- a/src/MetadataHydrator.php
+++ b/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];
         }
 
diff --git a/src/Middleware/TransformMiddleware.php b/src/Middleware/TransformMiddleware.php
index c8c44fa..33098c5 100644
--- a/src/Middleware/TransformMiddleware.php
+++ b/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;
 

From d85dc9171ad1c8ddfd741acb0315d1f4b31b0c0c Mon Sep 17 00:00:00 2001
From: David Badura <david.badura@patchlevel.de>
Date: Thu, 26 Feb 2026 12:57:17 +0100
Subject: [PATCH 5/5] optimize normalizer

---
 src/Guesser/MappedGuesser.php       |  2 --
 src/MetadataHydrator.php            |  1 -
 src/Normalizer/EnumNormalizer.php   | 25 +++++++++++++++----------
 src/Normalizer/ObjectNormalizer.php | 25 +++++++++++++++----------
 4 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/src/Guesser/MappedGuesser.php b/src/Guesser/MappedGuesser.php
index 7169d1c..da1fa11 100644
--- a/src/Guesser/MappedGuesser.php
+++ b/src/Guesser/MappedGuesser.php
@@ -7,8 +7,6 @@
 use Patchlevel\Hydrator\Normalizer\Normalizer;
 use Symfony\Component\TypeInfo\Type\ObjectType;
 
-use function array_key_exists;
-
 final readonly class MappedGuesser implements Guesser
 {
     /** @param array<class-string, class-string<Normalizer>> $map */
diff --git a/src/MetadataHydrator.php b/src/MetadataHydrator.php
index af95bda..ede8e20 100644
--- a/src/MetadataHydrator.php
+++ b/src/MetadataHydrator.php
@@ -14,7 +14,6 @@
 use Patchlevel\Hydrator\Normalizer\HydratorAwareNormalizer;
 use ReflectionClass;
 
-use function array_key_exists;
 use function is_array;
 
 use const PHP_VERSION_ID;
diff --git a/src/Normalizer/EnumNormalizer.php b/src/Normalizer/EnumNormalizer.php
index cf806d4..5bdb9b2 100644
--- a/src/Normalizer/EnumNormalizer.php
+++ b/src/Normalizer/EnumNormalizer.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 use BackedEnum;
+use RuntimeException;
 use Symfony\Component\TypeInfo\Type;
 use Symfony\Component\TypeInfo\Type\BackedEnumType;
 use Symfony\Component\TypeInfo\Type\NullableType;
@@ -30,12 +31,6 @@ public function normalize(mixed $value, array $context): mixed
             return null;
         }
 
-        $enum = $this->getEnum();
-
-        if (!$value instanceof $enum) {
-            throw InvalidArgument::withWrongType($enum . '|null', $value);
-        }
-
         return $value->value;
     }
 
@@ -50,10 +45,12 @@ public function denormalize(mixed $value, array $context): BackedEnum|null
             throw InvalidArgument::withWrongType('string|int|null', $value);
         }
 
-        $enum = $this->getEnum();
+        if ($this->enum === null) {
+            throw InvalidType::missingType();
+        }
 
         try {
-            return $enum::from($value);
+            return $this->enum::from($value);
         } catch (Throwable $error) {
             throw InvalidArgument::fromThrowable($error);
         }
@@ -61,7 +58,7 @@ public function denormalize(mixed $value, array $context): BackedEnum|null
 
     public function handleType(Type|null $type): void
     {
-        if ($this->enum !== null || $type === null) {
+        if ($type === null) {
             return;
         }
 
@@ -70,10 +67,18 @@ public function handleType(Type|null $type): void
         }
 
         if (!$type instanceof BackedEnumType) {
+            throw new RuntimeException();
+        }
+
+        if ($this->enum === null) {
+            $this->enum = $type->getClassName();
+
             return;
         }
 
-        $this->enum = $type->getClassName();
+        if (!$type->isIdentifiedBy($this->enum)) {
+            throw new RuntimeException();
+        }
     }
 
     /** @return class-string<BackedEnum> */
diff --git a/src/Normalizer/ObjectNormalizer.php b/src/Normalizer/ObjectNormalizer.php
index 6117f2d..cb90371 100644
--- a/src/Normalizer/ObjectNormalizer.php
+++ b/src/Normalizer/ObjectNormalizer.php
@@ -6,6 +6,7 @@
 
 use Attribute;
 use Patchlevel\Hydrator\Hydrator;
+use RuntimeException;
 use Symfony\Component\TypeInfo\Type;
 use Symfony\Component\TypeInfo\Type\GenericType;
 use Symfony\Component\TypeInfo\Type\NullableType;
@@ -34,12 +35,6 @@ public function normalize(mixed $value, array $context): mixed
             throw new MissingHydrator();
         }
 
-        $className = $this->getClassName();
-
-        if (!$value instanceof $className) {
-            throw InvalidArgument::withWrongType($className . '|null', $value);
-        }
-
         return $this->hydrator->extract($value, $context);
     }
 
@@ -54,9 +49,11 @@ public function denormalize(mixed $value, array $context): object|null
             throw new MissingHydrator();
         }
 
-        $className = $this->getClassName();
+        if ($this->className === null) {
+            throw InvalidType::missingType();
+        }
 
-        return $this->hydrator->hydrate($className, $value, $context);
+        return $this->hydrator->hydrate($this->className, $value, $context);
     }
 
     public function setHydrator(Hydrator $hydrator): void
@@ -66,7 +63,7 @@ public function setHydrator(Hydrator $hydrator): void
 
     public function handleType(Type|null $type): void
     {
-        if ($type === null || $this->className !== null) {
+        if ($type === null) {
             return;
         }
 
@@ -83,10 +80,18 @@ public function handleType(Type|null $type): void
         }
 
         if (!$type instanceof ObjectType) {
+            throw new RuntimeException();
+        }
+
+        if ($this->className === null) {
+            $this->className = $type->getClassName();
+
             return;
         }
 
-        $this->className = $type->getClassName();
+        if (!$type->isIdentifiedBy($this->className)) {
+            throw new RuntimeException();
+        }
     }
 
     /** @return class-string */