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// Copyright 2015 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_CORE_DOM_WEAK_IDENTIFIER_MAP_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_DOM_WEAK_IDENTIFIER_MAP_H_
#include "third_party/blink/renderer/platform/heap/handle.h"
#include "third_party/blink/renderer/platform/wtf/allocator.h"
#include "third_party/blink/renderer/platform/wtf/hash_map.h"
namespace blink {
// TODO(sof): WeakIdentifierMap<> belongs (out) in wtf/, but
// cannot until GarbageCollected<> can be used from WTF.
template <typename T, typename IdentifierType, bool isGarbageCollected>
class WeakIdentifierMapBase {
USING_FAST_MALLOC(WeakIdentifierMapBase);
protected:
using ObjectToIdentifier = HashMap<T*, IdentifierType>;
using IdentifierToObject = HashMap<IdentifierType, T*>;
ObjectToIdentifier object_to_identifier_;
IdentifierToObject identifier_to_object_;
};
template <typename T, typename IdentifierType>
class WeakIdentifierMapBase<T, IdentifierType, true>
: public GarbageCollected<WeakIdentifierMapBase<T, IdentifierType, true>> {
public:
void Trace(Visitor* visitor) {
visitor->Trace(object_to_identifier_);
visitor->Trace(identifier_to_object_);
}
protected:
using ObjectToIdentifier = HeapHashMap<WeakMember<T>, IdentifierType>;
using IdentifierToObject = HeapHashMap<IdentifierType, WeakMember<T>>;
ObjectToIdentifier object_to_identifier_;
IdentifierToObject identifier_to_object_;
};
template <typename T, typename IdentifierType = int>
class WeakIdentifierMap final
: public WeakIdentifierMapBase<T,
IdentifierType,
IsGarbageCollectedType<T>::value> {
public:
static IdentifierType Identifier(T* object) {
IdentifierType result = Instance().object_to_identifier_.at(object);
if (WTF::IsHashTraitsEmptyValue<HashTraits<IdentifierType>>(result)) {
result = Next();
Instance().Put(object, result);
}
return result;
}
WeakIdentifierMap() = default;
static T* Lookup(IdentifierType identifier) {
return Instance().identifier_to_object_.at(identifier);
}
static void NotifyObjectDestroyed(T* object) {
Instance().ObjectDestroyed(object);
}
private:
static WeakIdentifierMap<T, IdentifierType>& Instance();
static IdentifierType Next() {
static IdentifierType last_id = 0;
return ++last_id;
}
void Put(T* object, IdentifierType identifier) {
DCHECK(object && !this->object_to_identifier_.Contains(object));
this->object_to_identifier_.Set(object, identifier);
this->identifier_to_object_.Set(identifier, object);
}
void ObjectDestroyed(T* object) {
IdentifierType identifier = this->object_to_identifier_.Take(object);
if (!WTF::IsHashTraitsEmptyValue<HashTraits<IdentifierType>>(identifier))
this->identifier_to_object_.erase(identifier);
}
};
#define DECLARE_WEAK_IDENTIFIER_MAP(T, ...) \
template <> \
WeakIdentifierMap<T, ##__VA_ARGS__>& \
WeakIdentifierMap<T, ##__VA_ARGS__>::Instance(); \
extern template class WeakIdentifierMap<T, ##__VA_ARGS__>;
#define DEFINE_WEAK_IDENTIFIER_MAP(T, ...) \
template class WeakIdentifierMap<T, ##__VA_ARGS__>; \
template <> \
WeakIdentifierMap<T, ##__VA_ARGS__>& \
WeakIdentifierMap<T, ##__VA_ARGS__>::Instance() { \
using RefType = WeakIdentifierMap<T, ##__VA_ARGS__>; \
DEFINE_STATIC_LOCAL( \
Persistent<RefType>, map_instance, \
(MakeGarbageCollected<WeakIdentifierMap<T, ##__VA_ARGS__>>())); \
return *map_instance; \
}
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_DOM_WEAK_IDENTIFIER_MAP_H_
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