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Java > Open Source Codes > com > tc > asm > tree > analysis > Subroutine


1 /***
2  * ASM: a very small and fast Java bytecode manipulation framework
3  * Copyright (c) 2000-2005 INRIA, France Telecom
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the copyright holders nor the names of its
15  * contributors may be used to endorse or promote products derived from
16  * this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28  * THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 package com.tc.asm.tree.analysis;
31
32 import java.util.ArrayList JavaDoc;
33 import java.util.List JavaDoc;
34
35 import com.tc.asm.Label;
36 import com.tc.asm.tree.JumpInsnNode;
37
38 /**
39  * A method subroutine (corresponds to a JSR instruction).
40  *
41  * @author Eric Bruneton
42  */
43 class Subroutine {
44
45     Label start;
46
47     boolean[] access;
48
49     List JavaDoc callers;
50
51     private Subroutine() {
52     }
53
54     public Subroutine(
55         final Label start,
56         final int maxLocals,
57         final JumpInsnNode caller)
58     {
59         this.start = start;
60         this.access = new boolean[maxLocals];
61         this.callers = new ArrayList JavaDoc();
62         callers.add(caller);
63     }
64
65     public Subroutine copy() {
66         Subroutine result = new Subroutine();
67         result.start = start;
68         result.access = new boolean[access.length];
69         System.arraycopy(access, 0, result.access, 0, access.length);
70         result.callers = new ArrayList JavaDoc(callers);
71         return result;
72     }
73
74     public boolean merge(final Subroutine subroutine, boolean checkOverlap)
75             throws AnalyzerException
76     {
77         if (checkOverlap && subroutine.start != start) {
78             throw new AnalyzerException("Overlapping sub routines");
79         }
80         boolean changes = false;
81         for (int i = 0; i < access.length; ++i) {
82             if (subroutine.access[i] && !access[i]) {
83                 access[i] = true;
84                 changes = true;
85             }
86         }
87         for (int i = 0; i < subroutine.callers.size(); ++i) {
88             Object JavaDoc caller = subroutine.callers.get(i);
89             if (!callers.contains(caller)) {
90                 callers.add(caller);
91                 changes = true;
92             }
93         }
94         return changes;
95     }
96 }
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