92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
// Copyright (c) 2016 GitHub, Inc.
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// Use of this source code is governed by the MIT license that can be
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// found in the LICENSE file.
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#ifndef ATOM_COMMON_KEY_WEAK_MAP_H_
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#define ATOM_COMMON_KEY_WEAK_MAP_H_
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#include <unordered_map>
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#include <utility>
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#include <vector>
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#include "base/memory/linked_ptr.h"
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#include "v8/include/v8.h"
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namespace atom {
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// Like ES6's WeakMap, but the key is Integer and the value is Weak Pointer.
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template<typename K>
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class KeyWeakMap {
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public:
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// Records the key and self, used by SetWeak.
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struct KeyObject {
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K key;
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KeyWeakMap* self;
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};
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KeyWeakMap() {}
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virtual ~KeyWeakMap() {
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for (const auto& p : map_)
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p.second.second->ClearWeak();
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}
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// Sets the object to WeakMap with the given |key|.
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void Set(v8::Isolate* isolate, const K& key, v8::Local<v8::Object> object) {
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auto value = make_linked_ptr(new v8::Global<v8::Object>(isolate, object));
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KeyObject key_object = {key, this};
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auto& p = map_[key] = std::make_pair(key_object, value);
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value->SetWeak(&(p.first), OnObjectGC, v8::WeakCallbackType::kParameter);
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}
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// Gets the object from WeakMap by its |key|.
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v8::MaybeLocal<v8::Object> Get(v8::Isolate* isolate, const K& key) {
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auto iter = map_.find(key);
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if (iter == map_.end())
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return v8::MaybeLocal<v8::Object>();
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else
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return v8::Local<v8::Object>::New(isolate, *(iter->second.second));
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}
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// Whethere there is an object with |key| in this WeakMap.
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bool Has(const K& key) const {
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return map_.find(key) != map_.end();
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}
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// Returns all objects.
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std::vector<v8::Local<v8::Object>> Values(v8::Isolate* isolate) const {
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std::vector<v8::Local<v8::Object>> keys;
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keys.reserve(map_.size());
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for (const auto& iter : map_) {
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const auto& value = *(iter.second.second);
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keys.emplace_back(v8::Local<v8::Object>::New(isolate, value));
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}
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return keys;
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}
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// Remove object with |key| in the WeakMap.
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void Remove(const K& key) {
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auto iter = map_.find(key);
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if (iter == map_.end())
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return;
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iter->second.second->ClearWeak();
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map_.erase(iter);
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}
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private:
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static void OnObjectGC(
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const v8::WeakCallbackInfo<typename KeyWeakMap<K>::KeyObject>& data) {
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KeyWeakMap<K>::KeyObject* key_object = data.GetParameter();
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key_object->self->Remove(key_object->key);
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}
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// Map of stored objects.
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std::unordered_map<
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K, std::pair<KeyObject, linked_ptr<v8::Global<v8::Object>>>> map_;
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DISALLOW_COPY_AND_ASSIGN(KeyWeakMap);
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};
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} // namespace atom
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#endif // ATOM_COMMON_KEY_WEAK_MAP_H_
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