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1// Copyright 2021 the V8 project authors. All rights reserved.2// Use of this source code is governed by a BSD-style license that can be3// found in the LICENSE file.4 5#ifndef INCLUDE_CPPGC_OBJECT_SIZE_TRAIT_H_6#define INCLUDE_CPPGC_OBJECT_SIZE_TRAIT_H_7 8#include <cstddef>9 10#include "cppgc/type-traits.h"11#include "v8config.h"  // NOLINT(build/include_directory)12 13namespace cppgc {14 15namespace internal {16 17struct V8_EXPORT BaseObjectSizeTrait {18 protected:19  static size_t GetObjectSizeForGarbageCollected(const void*);20  static size_t GetObjectSizeForGarbageCollectedMixin(const void*);21};22 23}  // namespace internal24 25namespace subtle {26 27/**28 * Trait specifying how to get the size of an object that was allocated using29 * `MakeGarbageCollected()`. Also supports querying the size with an inner30 * pointer to a mixin.31 */32template <typename T, bool = IsGarbageCollectedMixinTypeV<T>>33struct ObjectSizeTrait;34 35template <typename T>36struct ObjectSizeTrait<T, false> : cppgc::internal::BaseObjectSizeTrait {37  static_assert(sizeof(T), "T must be fully defined");38  static_assert(IsGarbageCollectedTypeV<T>,39                "T must be of type GarbageCollected or GarbageCollectedMixin");40 41  static size_t GetSize(const T& object) {42    return GetObjectSizeForGarbageCollected(&object);43  }44};45 46template <typename T>47struct ObjectSizeTrait<T, true> : cppgc::internal::BaseObjectSizeTrait {48  static_assert(sizeof(T), "T must be fully defined");49 50  static size_t GetSize(const T& object) {51    return GetObjectSizeForGarbageCollectedMixin(&object);52  }53};54 55}  // namespace subtle56}  // namespace cppgc57 58#endif  // INCLUDE_CPPGC_OBJECT_SIZE_TRAIT_H_59