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//#define LOG_NDEBUG 0
18#define LOG_TAG "AHierarchicalStateMachine"
19#include <utils/Log.h>
20
21#include <media/stagefright/foundation/AHierarchicalStateMachine.h>
22
23#include <media/stagefright/foundation/ADebug.h>
24#include <media/stagefright/foundation/AMessage.h>
25#include <utils/Vector.h>
26
27namespace android {
28
29AState::AState(const sp<AState> &parentState)
30    : mParentState(parentState) {
31}
32
33AState::~AState() {
34}
35
36sp<AState> AState::parentState() {
37    return mParentState;
38}
39
40void AState::stateEntered() {
41}
42
43void AState::stateExited() {
44}
45
46////////////////////////////////////////////////////////////////////////////////
47
48AHierarchicalStateMachine::AHierarchicalStateMachine() {
49}
50
51AHierarchicalStateMachine::~AHierarchicalStateMachine() {
52}
53
54void AHierarchicalStateMachine::handleMessage(const sp<AMessage> &msg) {
55    sp<AState> save = mState;
56
57    sp<AState> cur = mState;
58    while (cur != NULL && !cur->onMessageReceived(msg)) {
59        // If you claim not to have handled the message you shouldn't
60        // have called setState...
61        CHECK(save == mState);
62
63        cur = cur->parentState();
64    }
65
66    if (cur != NULL) {
67        return;
68    }
69
70    ALOGW("Warning message %s unhandled in root state.",
71         msg->debugString().c_str());
72}
73
74void AHierarchicalStateMachine::changeState(const sp<AState> &state) {
75    if (state == mState) {
76        // Quick exit for the easy case.
77        return;
78    }
79
80    Vector<sp<AState> > A;
81    sp<AState> cur = mState;
82    for (;;) {
83        A.push(cur);
84        if (cur == NULL) {
85            break;
86        }
87        cur = cur->parentState();
88    }
89
90    Vector<sp<AState> > B;
91    cur = state;
92    for (;;) {
93        B.push(cur);
94        if (cur == NULL) {
95            break;
96        }
97        cur = cur->parentState();
98    }
99
100    // Remove the common tail.
101    while (A.size() > 0 && B.size() > 0 && A.top() == B.top()) {
102        A.pop();
103        B.pop();
104    }
105
106    mState = state;
107
108    for (size_t i = 0; i < A.size(); ++i) {
109        A.editItemAt(i)->stateExited();
110    }
111
112    for (size_t i = B.size(); i > 0;) {
113        i--;
114        B.editItemAt(i)->stateEntered();
115    }
116}
117
118}  // namespace android
119