Update Files

v8/include/cppgc/object-size-trait.h

@@ -0,0 +1,58 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef INCLUDE_CPPGC_OBJECT_SIZE_TRAIT_H_
+#define INCLUDE_CPPGC_OBJECT_SIZE_TRAIT_H_
+
+#include <cstddef>
+
+#include "cppgc/type-traits.h"
+#include "v8config.h"  // NOLINT(build/include_directory)
+
+namespace cppgc {
+
+namespace internal {
+
+struct V8_EXPORT BaseObjectSizeTrait {
+ protected:
+  static size_t GetObjectSizeForGarbageCollected(const void*);
+  static size_t GetObjectSizeForGarbageCollectedMixin(const void*);
+};
+
+}  // namespace internal
+
+namespace subtle {
+
+/**
+ * Trait specifying how to get the size of an object that was allocated using
+ * `MakeGarbageCollected()`. Also supports querying the size with an inner
+ * pointer to a mixin.
+ */
+template <typename T, bool = IsGarbageCollectedMixinTypeV<T>>
+struct ObjectSizeTrait;
+
+template <typename T>
+struct ObjectSizeTrait<T, false> : cppgc::internal::BaseObjectSizeTrait {
+  static_assert(sizeof(T), "T must be fully defined");
+  static_assert(IsGarbageCollectedTypeV<T>,
+                "T must be of type GarbageCollected or GarbageCollectedMixin");
+
+  static size_t GetSize(const T& object) {
+    return GetObjectSizeForGarbageCollected(&object);
+  }
+};
+
+template <typename T>
+struct ObjectSizeTrait<T, true> : cppgc::internal::BaseObjectSizeTrait {
+  static_assert(sizeof(T), "T must be fully defined");
+
+  static size_t GetSize(const T& object) {
+    return GetObjectSizeForGarbageCollectedMixin(&object);
+  }
+};
+
+}  // namespace subtle
+}  // namespace cppgc
+
+#endif  // INCLUDE_CPPGC_OBJECT_SIZE_TRAIT_H_