Make KeyWeakMap a template class

atom/common/key_weak_map.h

@@ -0,0 +1,98 @@
+// 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/memory/linked_ptr.h"
+#include "v8/include/v8.h"
+
+namespace atom {
+
+namespace internal {
+
+}  // namespace internal
+
+// 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 (const 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) {
+    auto value = make_linked_ptr(new v8::Global<v8::Object>(isolate, object));
+    KeyObject key_object = {key, this};
+    auto& p = map_[key] = std::make_pair(key_object, value);
+    value->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) {
+    std::vector<v8::Local<v8::Object>> keys;
+    keys.reserve(map_.size());
+    for (const auto& iter : map_) {
+      const auto& value = *(iter.second.second);
+      keys.emplace_back(v8::Local<v8::Object>::New(isolate, value));
+    }
+    return keys;
+  }
+
+  // Remove object with |key| in the WeakMap.
+  void Remove(const K& key) {
+    auto iter = map_.find(key);
+    if (iter == map_.end()) {
+      LOG(WARNING) << "Removing unexist object with ID " << key;
+      return;
+    }
+
+    iter->second.second->ClearWeak();
+    map_.erase(iter);
+  }
+
+ private:
+  static void OnObjectGC(
+      const v8::WeakCallbackInfo<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, linked_ptr<v8::Global<v8::Object>>>> map_;
+
+  DISALLOW_COPY_AND_ASSIGN(KeyWeakMap);
+};
+
+}  // namespace atom
+
+#endif  // ATOM_COMMON_KEY_WEAK_MAP_H_