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// 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_TRACE_TRAIT_H_
#define INCLUDE_CPPGC_TRACE_TRAIT_H_
#include <type_traits>
#include "cppgc/type-traits.h"
namespace cppgc {
class Visitor;
namespace internal {
template <typename T,
bool =
IsGarbageCollectedMixinTypeV<typename std::remove_const<T>::type>>
struct TraceTraitImpl;
} // namespace internal
using TraceCallback = void (*)(Visitor*, const void*);
// TraceDescriptor is used to describe how to trace an object.
struct TraceDescriptor {
// The adjusted base pointer of the object that should be traced.
const void* base_object_payload;
// A callback for tracing the object.
TraceCallback callback;
};
template <typename T>
struct TraceTrait {
static_assert(internal::IsTraceableV<T>, "T must have a Trace() method");
static TraceDescriptor GetTraceDescriptor(const void* self) {
return internal::TraceTraitImpl<T>::GetTraceDescriptor(
static_cast<const T*>(self));
}
static void Trace(Visitor* visitor, const void* self) {
static_cast<const T*>(self)->Trace(visitor);
}
};
namespace internal {
template <typename T>
struct TraceTraitImpl<T, false> {
static TraceDescriptor GetTraceDescriptor(const void* self) {
return {self, TraceTrait<T>::Trace};
}
};
template <typename T>
struct TraceTraitImpl<T, true> {
static TraceDescriptor GetTraceDescriptor(const void* self) {
return static_cast<const T*>(self)->GetTraceDescriptor();
}
};
} // namespace internal
} // namespace cppgc
#endif // INCLUDE_CPPGC_TRACE_TRAIT_H_
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