1 /*
2  * Copyright (C) 2010 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef A_HIERARCHICAL_STATE_MACHINE_H_
18 
19 #define A_HIERARCHICAL_STATE_MACHINE_H_
20 
21 #include <media/stagefright/foundation/AHandler.h>
22 
23 namespace android {
24 
25 struct AState : public RefBase {
26     AState(const sp<AState> &parentState = NULL);
27 
28     sp<AState> parentState();
29 
30 protected:
31     virtual ~AState();
32 
33     virtual void stateEntered();
34     virtual void stateExited();
35 
36     virtual bool onMessageReceived(const sp<AMessage> &msg) = 0;
37 
38 private:
39     friend struct AHierarchicalStateMachine;
40 
41     sp<AState> mParentState;
42 
43     DISALLOW_EVIL_CONSTRUCTORS(AState);
44 };
45 
46 struct AHierarchicalStateMachine {
47     AHierarchicalStateMachine();
48 
49 protected:
50     virtual ~AHierarchicalStateMachine();
51 
52     virtual void handleMessage(const sp<AMessage> &msg);
53 
54     // Only to be called in response to a message.
55     void changeState(const sp<AState> &state);
56 
57 private:
58     sp<AState> mState;
59 
60     DISALLOW_EVIL_CONSTRUCTORS(AHierarchicalStateMachine);
61 };
62 
63 }  // namespace android
64 
65 #endif  // A_HIERARCHICAL_STATE_MACHINE_H_
66