01: /***
02: * ASM Guide
03: * Copyright (c) 2007 Eric Bruneton
04: * All rights reserved.
05: *
06: * Redistribution and use in source and binary forms, with or without
07: * modification, are permitted provided that the following conditions
08: * are met:
09: * 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: */package ch3.sec2;
30:
31: import static org.objectweb.asm.Opcodes.IADD;
32: import static org.objectweb.asm.Opcodes.ICONST_0;
33:
34: import org.objectweb.asm.MethodVisitor;
35:
36: /**
37: * ASM Guide example class.
38: *
39: * @author Eric Bruneton
40: */
41: public class RemoveAddZeroAdapter extends PatternMethodAdapter {
42:
43: private static int SEEN_ICONST_0 = 1;
44:
45: public RemoveAddZeroAdapter(MethodVisitor mv) {
46: super (mv);
47: }
48:
49: public void visitInsn(int opcode) {
50: if (state == SEEN_ICONST_0) {
51: if (opcode == IADD) {
52: state = SEEN_NOTHING;
53: return;
54: }
55: }
56: visitInsn();
57: if (opcode == ICONST_0) {
58: state = SEEN_ICONST_0;
59: return;
60: }
61: mv.visitInsn(opcode);
62: }
63:
64: protected void visitInsn() {
65: if (state == SEEN_ICONST_0) {
66: mv.visitInsn(ICONST_0);
67: }
68: state = SEEN_NOTHING;
69: }
70: }
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