/src/node/deps/v8/include/cppgc/trace-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_TRACE_TRAIT_H_ |
6 | | #define INCLUDE_CPPGC_TRACE_TRAIT_H_ |
7 | | |
8 | | #include <type_traits> |
9 | | |
10 | | #include "cppgc/type-traits.h" |
11 | | #include "v8config.h" // NOLINT(build/include_directory) |
12 | | |
13 | | namespace cppgc { |
14 | | |
15 | | class Visitor; |
16 | | |
17 | | namespace internal { |
18 | | |
19 | | class RootVisitor; |
20 | | |
21 | | using TraceRootCallback = void (*)(RootVisitor&, const void* object); |
22 | | |
23 | | // Implementation of the default TraceTrait handling GarbageCollected and |
24 | | // GarbageCollectedMixin. |
25 | | template <typename T, |
26 | | bool = IsGarbageCollectedMixinTypeV<std::remove_const_t<T>>> |
27 | | struct TraceTraitImpl; |
28 | | |
29 | | } // namespace internal |
30 | | |
31 | | /** |
32 | | * Callback for invoking tracing on a given object. |
33 | | * |
34 | | * \param visitor The visitor to dispatch to. |
35 | | * \param object The object to invoke tracing on. |
36 | | */ |
37 | | using TraceCallback = void (*)(Visitor* visitor, const void* object); |
38 | | |
39 | | /** |
40 | | * Describes how to trace an object, i.e., how to visit all Oilpan-relevant |
41 | | * fields of an object. |
42 | | */ |
43 | | struct TraceDescriptor { |
44 | | /** |
45 | | * Adjusted base pointer, i.e., the pointer to the class inheriting directly |
46 | | * from GarbageCollected, of the object that is being traced. |
47 | | */ |
48 | | const void* base_object_payload; |
49 | | /** |
50 | | * Callback for tracing the object. |
51 | | */ |
52 | | TraceCallback callback; |
53 | | }; |
54 | | |
55 | | /** |
56 | | * Callback for getting a TraceDescriptor for a given address. |
57 | | * |
58 | | * \param address Possibly inner address of an object. |
59 | | * \returns a TraceDescriptor for the provided address. |
60 | | */ |
61 | | using TraceDescriptorCallback = TraceDescriptor (*)(const void* address); |
62 | | |
63 | | namespace internal { |
64 | | |
65 | | struct V8_EXPORT TraceTraitFromInnerAddressImpl { |
66 | | static TraceDescriptor GetTraceDescriptor(const void* address); |
67 | | }; |
68 | | |
69 | | /** |
70 | | * Trait specifying how the garbage collector processes an object of type T. |
71 | | * |
72 | | * Advanced users may override handling by creating a specialization for their |
73 | | * type. |
74 | | */ |
75 | | template <typename T> |
76 | | struct TraceTraitBase { |
77 | | static_assert(internal::IsTraceableV<T>, "T must have a Trace() method"); |
78 | | |
79 | | /** |
80 | | * Accessor for retrieving a TraceDescriptor to process an object of type T. |
81 | | * |
82 | | * \param self The object to be processed. |
83 | | * \returns a TraceDescriptor to process the object. |
84 | | */ |
85 | 0 | static TraceDescriptor GetTraceDescriptor(const void* self) { |
86 | 0 | return internal::TraceTraitImpl<T>::GetTraceDescriptor( |
87 | 0 | static_cast<const T*>(self)); |
88 | 0 | } |
89 | | |
90 | | /** |
91 | | * Function invoking the tracing for an object of type T. |
92 | | * |
93 | | * \param visitor The visitor to dispatch to. |
94 | | * \param self The object to invoke tracing on. |
95 | | */ |
96 | 0 | static void Trace(Visitor* visitor, const void* self) { |
97 | 0 | static_cast<const T*>(self)->Trace(visitor); |
98 | 0 | } Unexecuted instantiation: cppgc::internal::TraceTraitBase<v8::Object::Wrappable>::Trace(cppgc::Visitor*, void const*) Unexecuted instantiation: cppgc::internal::TraceTraitBase<node::contextify::ContextifyContext>::Trace(cppgc::Visitor*, void const*) Unexecuted instantiation: cppgc::internal::TraceTraitBase<node::contextify::ContextifyScript>::Trace(cppgc::Visitor*, void const*) |
99 | | }; |
100 | | |
101 | | } // namespace internal |
102 | | |
103 | | template <typename T> |
104 | | struct TraceTrait : public internal::TraceTraitBase<T> {}; |
105 | | |
106 | | namespace internal { |
107 | | |
108 | | template <typename T> |
109 | | struct TraceTraitImpl<T, false> { |
110 | | static_assert(IsGarbageCollectedTypeV<T>, |
111 | | "T must be of type GarbageCollected or GarbageCollectedMixin"); |
112 | | static TraceDescriptor GetTraceDescriptor(const void* self) { |
113 | | return {self, TraceTrait<T>::Trace}; |
114 | | } |
115 | | }; |
116 | | |
117 | | template <typename T> |
118 | | struct TraceTraitImpl<T, true> { |
119 | 0 | static TraceDescriptor GetTraceDescriptor(const void* self) { |
120 | 0 | return internal::TraceTraitFromInnerAddressImpl::GetTraceDescriptor(self); |
121 | 0 | } |
122 | | }; |
123 | | |
124 | | } // namespace internal |
125 | | } // namespace cppgc |
126 | | |
127 | | #endif // INCLUDE_CPPGC_TRACE_TRAIT_H_ |