v8 12.4.254 (node 22.4.1)
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finalizer-trait.h
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1// Copyright 2020 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef INCLUDE_CPPGC_INTERNAL_FINALIZER_TRAIT_H_
6#define INCLUDE_CPPGC_INTERNAL_FINALIZER_TRAIT_H_
7
8#include <type_traits>
9
10#include "cppgc/type-traits.h"
11
12namespace cppgc {
13namespace internal {
14
15using FinalizationCallback = void (*)(void*);
16
17template <typename T, typename = void>
18struct HasFinalizeGarbageCollectedObject : std::false_type {};
19
20template <typename T>
22 T,
23 std::void_t<decltype(std::declval<T>().FinalizeGarbageCollectedObject())>>
24 : std::true_type {};
25
26// The FinalizerTraitImpl specifies how to finalize objects.
27template <typename T, bool isFinalized>
29
30template <typename T>
32 private:
33 // Dispatch to custom FinalizeGarbageCollectedObject().
34 struct Custom {
35 static void Call(void* obj) {
36 static_cast<T*>(obj)->FinalizeGarbageCollectedObject();
37 }
38 };
39
40 // Dispatch to regular destructor.
41 struct Destructor {
42 static void Call(void* obj) { static_cast<T*>(obj)->~T(); }
43 };
44
45 using FinalizeImpl =
46 std::conditional_t<HasFinalizeGarbageCollectedObject<T>::value, Custom,
47 Destructor>;
48
49 public:
50 static void Finalize(void* obj) {
51 static_assert(sizeof(T), "T must be fully defined");
52 FinalizeImpl::Call(obj);
53 }
54};
55
56template <typename T>
58 static void Finalize(void* obj) {
59 static_assert(sizeof(T), "T must be fully defined");
60 }
61};
62
63// The FinalizerTrait is used to determine if a type requires finalization and
64// what finalization means.
65template <typename T>
67 private:
68 // Object has a finalizer if it has
69 // - a custom FinalizeGarbageCollectedObject method, or
70 // - a destructor.
71 static constexpr bool kNonTrivialFinalizer =
73 !std::is_trivially_destructible<typename std::remove_cv<T>::type>::value;
74
75 static void Finalize(void* obj) {
77 }
78
79 public:
80 static constexpr bool HasFinalizer() { return kNonTrivialFinalizer; }
81
82 // The callback used to finalize an object of type T.
84 kNonTrivialFinalizer ? Finalize : nullptr;
85};
86
87template <typename T>
89
90} // namespace internal
91} // namespace cppgc
92
93#endif // INCLUDE_CPPGC_INTERNAL_FINALIZER_TRAIT_H_
void(*)(void *) FinalizationCallback
static constexpr FinalizationCallback kCallback
static constexpr bool HasFinalizer()