1 package serp.bytecode;
2
3 import serp.bytecode.lowlevel.*;
4 import serp.bytecode.visitor.*;
5
6 /***
7 * An if instruction such as <code>ifnull, ifeq</code>, etc.
8 *
9 * @author Abe White
10 */
11 public class IfInstruction extends JumpInstruction {
12 IfInstruction(Code owner, int opcode) {
13 super(owner, opcode);
14 }
15
16 public int getStackChange() {
17 switch (getOpcode()) {
18 case Constants.IFACMPEQ:
19 case Constants.IFACMPNE:
20 case Constants.IFICMPEQ:
21 case Constants.IFICMPNE:
22 case Constants.IFICMPLT:
23 case Constants.IFICMPGT:
24 case Constants.IFICMPLE:
25 case Constants.IFICMPGE:
26 return -2;
27 case Constants.IFEQ:
28 case Constants.IFNE:
29 case Constants.IFLT:
30 case Constants.IFGT:
31 case Constants.IFLE:
32 case Constants.IFGE:
33 case Constants.IFNULL:
34 case Constants.IFNONNULL:
35 return -1;
36 default:
37 return super.getStackChange();
38 }
39 }
40
41 int getLength() {
42 return super.getLength() + 2;
43 }
44
45 public String getTypeName() {
46 switch (getOpcode()) {
47 case Constants.IFACMPEQ:
48 case Constants.IFACMPNE:
49 case Constants.IFNULL:
50 case Constants.IFNONNULL:
51 return "java.lang.Object";
52 default:
53 return "I";
54 }
55 }
56
57 public void acceptVisit(BCVisitor visit) {
58 visit.enterIfInstruction(this);
59 visit.exitIfInstruction(this);
60 }
61 }