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_EVENT_CALLBACK_H
17 #define FOUNDATION_ACE_FRAMEWORKS_BASE_UTILS_EVENT_CALLBACK_H
18 
19 #include <functional>
20 
21 #include "base/utils/base_id.h"
22 #include "base/utils/macros.h"
23 
24 namespace OHOS::Ace {
25 
26 template<class>
27 class EventCallback;
28 
29 template<class R, class... Args>
30 class ACE_FORCE_EXPORT EventCallback<R(Args...)> : public BaseId {
31 public:
32     using FunctionType = std::function<R(Args...)>;
33 
EventCallback()34     EventCallback() : callback_(nullptr) {}
EventCallback(FunctionType && callback)35     explicit EventCallback(FunctionType&& callback) : callback_(std::move(callback)) {}
EventCallback(const FunctionType & callback)36     explicit EventCallback(const FunctionType& callback) : callback_(callback) {}
37 
38     ~EventCallback() override = default;
39 
40     // Notice: uses operator bool to judge its legitimacy.
operator()41     R operator()(Args&&... args) const
42     {
43         return callback_(std::forward<Args>(args)...);
44     }
45 
46     explicit operator bool() const
47     {
48         return callback_ != nullptr;
49     }
50 
51     bool operator==(std::nullptr_t) const
52     {
53         return callback_ == nullptr;
54     }
55 
56     bool operator!=(std::nullptr_t) const
57     {
58         return callback_ != nullptr;
59     }
60 
61     bool operator==(const EventCallback& callback) const
62     {
63         return GetId() == callback.GetId();
64     }
65 
66     bool operator<(const EventCallback& callback) const
67     {
68         return GetId() < callback.GetId();
69     }
70 
GetCallback()71     const FunctionType& GetCallback() const
72     {
73         return callback_;
74     }
75 
76 private:
77     FunctionType callback_;
78 };
79 
80 } // namespace OHOS::Ace
81 
82 #endif // FOUNDATION_ACE_FRAMEWORKS_BASE_UTILS_EVENT_CALLBACK_H
83