1    /* 
2     * Javassist, a Java-bytecode translator toolkit. 
3     * Copyright (C) 1999-2003 Shigeru Chiba. All Rights Reserved. 
4     * 
5     * The contents of this file are subject to the Mozilla Public License Version 
6     * 1.1 (the "License"); you may not use this file except in compliance with 
7     * the License.  Alternatively, the contents of this file may be used under 
8     * the terms of the GNU Lesser General Public License Version 2.1 or later. 
9     * 
10    * Software distributed under the License is distributed on an "AS IS" basis, 
11    * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 
12    * for the specific language governing rights and limitations under the 
13    * License. 
14    */ 
15    
16   package javassist.runtime; 
17    
18   /** 
19    * A support class for implementing <code>$cflow</code>. 
20    * This support class is required at runtime 
21    * only if <code>$cflow</code> is used. 
22    * 
23    * @see javassist.CtBehavior#useCflow(String) 
24    */ 
25   public class Cflow extends ThreadLocal { 
26       private static class Depth { 
27           private int depth; 
28    
29           Depth() { 
30               depth = 0; 
31           } 
32    
33           int get() { 
34               return depth; 
35           } 
36    
37           void inc() { 
38               ++depth; 
39           } 
40    
41           void dec() { 
42               --depth; 
43           } 
44       } 
45    
46       protected synchronized Object initialValue() { 
47           return new Depth(); 
48       } 
49    
50       /** 
51        * Increments the counter. 
52        */ 
53       public void enter() { 
54           ((Depth) get()).inc(); 
55       } 
56    
57       /** 
58        * Decrements the counter. 
59        */ 
60       public void exit() { 
61           ((Depth) get()).dec(); 
62       } 
63    
64       /** 
65        * Returns the value of the counter. 
66        */ 
67       public int value() { 
68           return ((Depth) get()).get(); 
69       } 
70   } 
71