1 package org.apache.bcel.generic;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 /***
58 * Equality of instructions isn't clearly to be defined. You might
59 * wish, for example, to compare whether instructions have the same
60 * meaning. E.g., whether two INVOKEVIRTUALs describe the same
61 * call.<br>The DEFAULT comparator however, considers two instructions
62 * to be equal if they have same opcode and point to the same indexes
63 * (if any) in the constant pool or the same local variable index. Branch
64 * instructions must have the same target.
65 *
66 * @see Instruction
67 * @version $Id: InstructionComparator.java,v 1.3 2002/10/11 20:33:07 mdahm Exp $
68 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
69 */
70 public interface InstructionComparator {
71 public static final InstructionComparator DEFAULT =
72 new InstructionComparator() {
73 public boolean equals(Instruction i1, Instruction i2) {
74 if(i1.opcode == i2.opcode) {
75 if(i1 instanceof Select) {
76 InstructionHandle[] t1 = ((Select)i1).getTargets();
77 InstructionHandle[] t2 = ((Select)i2).getTargets();
78
79 if(t1.length == t2.length) {
80 for(int i = 0; i < t1.length; i++) {
81 if(t1[i] != t2[i]) {
82 return false;
83 }
84 }
85
86 return true;
87 }
88 } else if(i1 instanceof BranchInstruction) {
89 return ((BranchInstruction)i1).target ==
90 ((BranchInstruction)i2).target;
91 } else if(i1 instanceof ConstantPushInstruction) {
92 return ((ConstantPushInstruction)i1).getValue().
93 equals(((ConstantPushInstruction)i2).getValue());
94 } else if(i1 instanceof IndexedInstruction) {
95 return ((IndexedInstruction)i1).getIndex() ==
96 ((IndexedInstruction)i2).getIndex();
97 } else if(i1 instanceof NEWARRAY) {
98 return ((NEWARRAY)i1).getTypecode() == ((NEWARRAY)i2).getTypecode();
99 } else {
100 return true;
101 }
102 }
103
104 return false;
105 }
106 };
107
108 public boolean equals(Instruction i1, Instruction i2);
109 }
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