include/media/stagefright/foundation/AHierarchicalStateMachine.h

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef A_HIERARCHICAL_STATE_MACHINE_H_

#define A_HIERARCHICAL_STATE_MACHINE_H_

#include <media/stagefright/foundation/AHandler.h>

namespace android {

struct AState : public RefBase {
    AState(const sp<AState> &parentState = NULL);

    sp<AState> parentState();

protected:
    virtual ~AState();

    virtual void stateEntered();
    virtual void stateExited();

    virtual bool onMessageReceived(const sp<AMessage> &msg) = 0;

private:
    friend struct AHierarchicalStateMachine;

    sp<AState> mParentState;

    DISALLOW_EVIL_CONSTRUCTORS(AState);
};

struct AHierarchicalStateMachine : public AHandler {
    AHierarchicalStateMachine();

protected:
    virtual ~AHierarchicalStateMachine();

    virtual void onMessageReceived(const sp<AMessage> &msg);

    // Only to be called in response to a message.
    void changeState(const sp<AState> &state);

private:
    sp<AState> mState;

    DISALLOW_EVIL_CONSTRUCTORS(AHierarchicalStateMachine);
};

}  // namespace android

#endif  // A_HIERARCHICAL_STATE_MACHINE_H_