v8/include/cppgc/internal/finalizer-trait.h
Michael Lippautz eefd5d31a2 cppgc: Add public target to build against
- Fixes includes to be relative to include/ which allows embedders
  to just add V8's include directory to get started.
- Adds public target for the library as "cppgc".

Bug: chromium:1056170
Change-Id: Iec9b644e20016a5d7281275b739821a050fd2540
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2157366
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67278}
2020-04-21 12:48:23 +00:00

91 lines
2.5 KiB
C++

// Copyright 2020 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_INTERNAL_FINALIZER_TRAIT_H_
#define INCLUDE_CPPGC_INTERNAL_FINALIZER_TRAIT_H_
#include <type_traits>
#include "cppgc/type-traits.h"
namespace cppgc {
namespace internal {
using FinalizationCallback = void (*)(void*);
template <typename T, typename = void>
struct HasFinalizeGarbageCollectedObject : std::false_type {};
template <typename T>
struct HasFinalizeGarbageCollectedObject<
T, void_t<decltype(std::declval<T>().FinalizeGarbageCollectedObject())>>
: std::true_type {};
// The FinalizerTraitImpl specifies how to finalize objects.
template <typename T, bool isFinalized>
struct FinalizerTraitImpl;
template <typename T>
struct FinalizerTraitImpl<T, true> {
private:
// Dispatch to custom FinalizeGarbageCollectedObject().
struct Custom {
static void Call(void* obj) {
static_cast<T*>(obj)->FinalizeGarbageCollectedObject();
}
};
// Dispatch to regular destructor.
struct Destructor {
static void Call(void* obj) { static_cast<T*>(obj)->~T(); }
};
using FinalizeImpl =
std::conditional_t<HasFinalizeGarbageCollectedObject<T>::value, Custom,
Destructor>;
public:
static void Finalize(void* obj) {
static_assert(sizeof(T), "T must be fully defined");
FinalizeImpl::Call(obj);
}
};
template <typename T>
struct FinalizerTraitImpl<T, false> {
static void Finalize(void* obj) {
static_assert(sizeof(T), "T must be fully defined");
}
};
// The FinalizerTrait is used to determine if a type requires finalization and
// what finalization means.
template <typename T>
struct FinalizerTrait {
private:
// Object has a finalizer if it has
// - a custom FinalizeGarbageCollectedObject method, or
// - a destructor.
static constexpr bool kNonTrivialFinalizer =
internal::HasFinalizeGarbageCollectedObject<T>::value ||
!std::is_trivially_destructible<typename std::remove_cv<T>::type>::value;
static void Finalize(void* obj) {
internal::FinalizerTraitImpl<T, kNonTrivialFinalizer>::Finalize(obj);
}
public:
// The callback used to finalize an object of type T.
static constexpr FinalizationCallback kCallback =
kNonTrivialFinalizer ? Finalize : nullptr;
};
template <typename T>
constexpr FinalizationCallback FinalizerTrait<T>::kCallback;
} // namespace internal
} // namespace cppgc
#endif // INCLUDE_CPPGC_INTERNAL_FINALIZER_TRAIT_H_