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