1 /**
2  * Copyright (C) 2011 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 package com.android.internal.util;
18 
19 import android.os.Message;
20 
21 /**
22  * {@hide}
23  *
24  * The interface for implementing states in a {@link StateMachine}
25  */
26 public interface IState {
27 
28     /**
29      * Returned by processMessage to indicate the the message was processed.
30      */
31     static final boolean HANDLED = true;
32 
33     /**
34      * Returned by processMessage to indicate the the message was NOT processed.
35      */
36     static final boolean NOT_HANDLED = false;
37 
38     /**
39      * Called when a state is entered.
40      */
enter()41     void enter();
42 
43     /**
44      * Called when a state is exited.
45      */
exit()46     void exit();
47 
48     /**
49      * Called when a message is to be processed by the
50      * state machine.
51      *
52      * This routine is never reentered thus no synchronization
53      * is needed as only one processMessage method will ever be
54      * executing within a state machine at any given time. This
55      * does mean that processing by this routine must be completed
56      * as expeditiously as possible as no subsequent messages will
57      * be processed until this routine returns.
58      *
59      * @param msg to process
60      * @return HANDLED if processing has completed and NOT_HANDLED
61      *         if the message wasn't processed.
62      */
processMessage(Message msg)63     boolean processMessage(Message msg);
64 
65     /**
66      * Name of State for debugging purposes.
67      *
68      * @return name of state.
69      */
getName()70     String getName();
71 }
72