From cd93b9412c2620aa01ab5534a94620d9d01f2738 Mon Sep 17 00:00:00 2001
From: Cheng Zhao <zcbenz@gmail.com>
Date: Wed, 24 Jun 2015 13:22:09 +0800
Subject: [PATCH] Add C++ version of IDWeakMap

---
 atom/common/id_weak_map.cc | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 atom/common/id_weak_map.h  | 55 ++++++++++++++++++++++++++++++++++++
 filenames.gypi             |  2 ++
 3 files changed, 127 insertions(+)
 create mode 100644 atom/common/id_weak_map.cc
 create mode 100644 atom/common/id_weak_map.h

diff --git a/atom/common/id_weak_map.cc b/atom/common/id_weak_map.cc
new file mode 100644
index 0000000..556b9ba
--- /dev/null
+++ b/atom/common/id_weak_map.cc
@@ -0,0 +1,70 @@
+// Copyright (c) 2015 GitHub, Inc.
+// Use of this source code is governed by the MIT license that can be
+// found in the LICENSE file.
+
+#include "atom/common/id_weak_map.h"
+
+#include <utility>
+
+#include "native_mate/converter.h"
+
+namespace atom {
+
+IDWeakMap::IDWeakMap() : next_id_(0) {
+}
+
+IDWeakMap::~IDWeakMap() {
+}
+
+int32_t IDWeakMap::Add(v8::Isolate* isolate, v8::Local<v8::Object> object) {
+  int32_t id = GetNextID();
+  object->SetHiddenValue(mate::StringToSymbol(isolate, "IDWeakMapKey"),
+                         mate::Converter<int32_t>::ToV8(isolate, id));
+
+  auto global = make_linked_ptr(new v8::Global<v8::Object>(isolate, object));
+  global->SetWeak(this, &WeakCallback);
+  map_.emplace(id, global);
+  return id;
+}
+
+v8::MaybeLocal<v8::Object> IDWeakMap::Get(v8::Isolate* isolate, int32_t id) {
+  auto iter = map_.find(id);
+  if (iter == map_.end())
+    return v8::MaybeLocal<v8::Object>();
+  else
+    return v8::Local<v8::Object>::New(isolate, *iter->second);
+}
+
+bool IDWeakMap::Has(int32_t id) const {
+  return map_.find(id) != map_.end();
+}
+
+std::vector<int32_t> IDWeakMap::Keys() const {
+  std::vector<int32_t> keys;
+  keys.reserve(map_.size());
+  for (const auto& iter : map_)
+    keys.emplace_back(iter.first);
+  return keys;
+}
+
+void IDWeakMap::Remove(int32_t id) {
+  auto iter = map_.find(id);
+  if (iter == map_.end())
+    LOG(WARNING) << "Removing unexist object with ID " << id;
+  else
+    map_.erase(iter);
+}
+
+int IDWeakMap::GetNextID() {
+  return ++next_id_;
+}
+
+// static
+void IDWeakMap::WeakCallback(
+    const v8::WeakCallbackData<v8::Object, IDWeakMap>& data) {
+  int32_t id = data.GetValue()->GetHiddenValue(
+      mate::StringToV8(data.GetIsolate(), "IDWeakMapKey"))->Int32Value();
+  data.GetParameter()->Remove(id);
+}
+
+}  // namespace atom
diff --git a/atom/common/id_weak_map.h b/atom/common/id_weak_map.h
new file mode 100644
index 0000000..4ef3c05
--- /dev/null
+++ b/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_
diff --git a/filenames.gypi b/filenames.gypi
index f0c940a..8a23c38 100644
--- a/filenames.gypi
+++ b/filenames.gypi
@@ -254,6 +254,8 @@
       'atom/common/event_emitter_caller.cc',
       'atom/common/event_emitter_caller.h',
       'atom/common/google_api_key.h',
+      'atom/common/id_weak_map.cc',
+      'atom/common/id_weak_map.h',
       'atom/common/linux/application_info.cc',
       'atom/common/native_mate_converters/accelerator_converter.cc',
       'atom/common/native_mate_converters/accelerator_converter.h',
-- 
2.7.4