1 /*
2  * Copyright (c) 2021 Huawei Device Co., Ltd.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at
6  *
7  *     http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 
16 #ifndef FOUNDATION_ACE_FRAMEWORKS_BASE_UTILS_LISTENER_H
17 #define FOUNDATION_ACE_FRAMEWORKS_BASE_UTILS_LISTENER_H
18 
19 #include <unordered_map>
20 
21 #include "base/utils/event_callback.h"
22 
23 namespace OHOS::Ace {
24 
25 template<class T>
26 class ValueListenable {
27 public:
28     using ValueCallback = EventCallback<void(const T&)>;
29 
30     ValueListenable() = default;
31     virtual ~ValueListenable() = default;
32 
AddListener(const ValueCallback & callback)33     void AddListener(const ValueCallback& callback)
34     {
35         callbacks_.emplace(callback.GetId(), callback);
36     }
37 
38     template<class F>
AddListener(const F & funcObject)39     typename ValueCallback::IdType AddListener(const F& funcObject)
40     {
41         ValueCallback callback(funcObject);
42         AddListener(callback);
43         return callback.GetId();
44     }
45 
RemoveListener(const ValueCallback & callback)46     void RemoveListener(const ValueCallback& callback)
47     {
48         callbacks_.erase(callback.GetId());
49     }
50 
RemoveListener(typename ValueCallback::IdType id)51     void RemoveListener(typename ValueCallback::IdType id)
52     {
53         callbacks_.erase(id);
54     }
55 
ClearListeners()56     void ClearListeners()
57     {
58         callbacks_.clear();
59     }
60 
NotifyListener(const T & value)61     void NotifyListener(const T& value) const
62     {
63         auto callbacks = callbacks_;
64         for (auto&& [id, callback] : callbacks) {
65             if (callback) {
66                 callback(value);
67             }
68         }
69     }
70 
71 private:
72     std::unordered_map<typename ValueCallback::IdType, ValueCallback> callbacks_;
73 };
74 
75 } // namespace OHOS::Ace
76 
77 #endif // FOUNDATION_ACE_FRAMEWORKS_BASE_UTILS_LISTENER_H
78