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// Copyright 2021 The Chromium 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 THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_TRACE_TRAITS_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_TRACE_TRAITS_H_
#include "third_party/blink/renderer/platform/heap/heap.h"
#include "third_party/blink/renderer/platform/heap/member.h"
#include "third_party/blink/renderer/platform/heap/visitor.h"
#include "third_party/blink/renderer/platform/wtf/buildflags.h"
#include "third_party/blink/renderer/platform/wtf/hash_table.h"
#if BUILDFLAG(USE_V8_OILPAN)
#include "third_party/blink/renderer/platform/heap/v8_wrapper/trace_traits.h"
#else // !USE_V8_OILPAN
#include "third_party/blink/renderer/platform/heap/impl/trace_traits.h"
#endif // !USE_V8_OILPAN
namespace blink {
template <WTF::WeakHandlingFlag weakness,
typename T,
typename Traits,
bool = WTF::IsTraceableInCollectionTrait<Traits>::value,
WTF::WeakHandlingFlag = WTF::WeakHandlingTrait<T>::value>
struct TraceCollectionIfEnabled;
template <WTF::WeakHandlingFlag weakness, typename T, typename Traits>
struct TraceCollectionIfEnabled<weakness,
T,
Traits,
false,
WTF::kNoWeakHandling> {
STATIC_ONLY(TraceCollectionIfEnabled);
static bool IsAlive(const blink::LivenessBroker& info, const T&) {
return true;
}
static void Trace(Visitor*, const void*) {
static_assert(!WTF::IsTraceableInCollectionTrait<Traits>::value,
"T should not be traced");
}
};
template <typename T, typename Traits>
struct TraceCollectionIfEnabled<WTF::kNoWeakHandling,
T,
Traits,
false,
WTF::kWeakHandling> {
STATIC_ONLY(TraceCollectionIfEnabled);
static void Trace(Visitor* visitor, const void* t) {
WTF::TraceInCollectionTrait<WTF::kNoWeakHandling, T, Traits>::Trace(
visitor, *reinterpret_cast<const T*>(t));
}
};
template <WTF::WeakHandlingFlag weakness,
typename T,
typename Traits,
bool,
WTF::WeakHandlingFlag>
struct TraceCollectionIfEnabled {
STATIC_ONLY(TraceCollectionIfEnabled);
static bool IsAlive(const blink::LivenessBroker& info, const T& traceable) {
return WTF::TraceInCollectionTrait<weakness, T, Traits>::IsAlive(info,
traceable);
}
static void Trace(Visitor* visitor, const void* t) {
static_assert(WTF::IsTraceableInCollectionTrait<Traits>::value ||
weakness == WTF::kWeakHandling,
"Traits should be traced");
WTF::TraceInCollectionTrait<weakness, T, Traits>::Trace(
visitor, *reinterpret_cast<const T*>(t));
}
};
} // namespace blink
namespace WTF {
// Catch-all for types that have a way to trace that don't have special
// handling for weakness in collections. This means that if this type
// contains WeakMember fields, they will simply be zeroed, but the entry
// will not be removed from the collection. This always happens for
// things in vectors, which don't currently support special handling of
// weak elements.
template <typename T, typename Traits>
struct TraceInCollectionTrait<kNoWeakHandling, T, Traits> {
static bool IsAlive(const blink::LivenessBroker& info, const T& t) {
return true;
}
static void Trace(blink::Visitor* visitor, const T& t) {
static_assert(IsTraceableInCollectionTrait<Traits>::value,
"T should be traceable");
visitor->Trace(t);
}
};
template <typename T, typename Traits>
struct TraceInCollectionTrait<kNoWeakHandling, blink::WeakMember<T>, Traits> {
static void Trace(blink::Visitor* visitor, const blink::WeakMember<T>& t) {
// Extract raw pointer to avoid using the WeakMember<> overload in Visitor.
visitor->TraceStrongly(t);
}
};
// Catch-all for types that have HashTrait support for tracing with weakness.
// Empty to enforce specialization.
template <typename T, typename Traits>
struct TraceInCollectionTrait<kWeakHandling, T, Traits> {};
template <typename T, typename Traits>
struct TraceInCollectionTrait<kWeakHandling, blink::WeakMember<T>, Traits> {
static bool IsAlive(const blink::LivenessBroker& info,
const blink::WeakMember<T>& value) {
return info.IsHeapObjectAlive(value);
}
};
} // namespace WTF
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_TRACE_TRAITS_H_
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