electron/shell/common/key_weak_map.h
2019-06-19 17:33:28 -07:00

87 lines
2.4 KiB
C++

// 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 SHELL_COMMON_KEY_WEAK_MAP_H_
#define SHELL_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 // SHELL_COMMON_KEY_WEAK_MAP_H_