Add C++ version of IDWeakMap

atom/common/id_weak_map.h

@@ -0,0 +1,55 @@
+// Copyright (c) 2015 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#ifndef ATOM_COMMON_ID_WEAK_MAP_H_
+#define ATOM_COMMON_ID_WEAK_MAP_H_
+
+#include <unordered_map>
+#include <vector>
+
+#include "base/memory/linked_ptr.h"
+#include "v8/include/v8.h"
+
+namespace atom {
+
+// Like ES6's WeakMap, but the key is Integer and the value is Weak Pointer.
+class IDWeakMap {
+ public:
+  IDWeakMap();
+  ~IDWeakMap();
+
+  // Adds |object| to WeakMap and returns its allocated |id|.
+  int32_t Add(v8::Isolate* isolate, v8::Local<v8::Object> object);
+
+  // Gets the object from WeakMap by its |id|.
+  v8::MaybeLocal<v8::Object> Get(v8::Isolate* isolate, int32_t id);
+
+  // Whethere there is an object with |id| in this WeakMap.
+  bool Has(int32_t id) const;
+
+  // Returns IDs of all available objects.
+  std::vector<int32_t> Keys() const;
+
+  // Remove object with |id| in the WeakMap.
+  void Remove(int32_t key);
+
+ private:
+  // Returns next available ID.
+  int GetNextID();
+
+  static void WeakCallback(
+      const v8::WeakCallbackData<v8::Object, IDWeakMap>& data);
+
+  // ID of next stored object.
+  int32_t next_id_;
+
+  // Map of stored objects.
+  std::unordered_map<int32_t, linked_ptr<v8::Global<v8::Object>>> map_;
+
+  DISALLOW_COPY_AND_ASSIGN(IDWeakMap);
+};
+
+}  // namespace atom
+
+#endif  // ATOM_COMMON_ID_WEAK_MAP_H_