1 package serp.bytecode;
2
3 import java.io.*;
4
5 import serp.bytecode.lowlevel.*;
6 import serp.bytecode.visitor.*;
7
8 /***
9 * An instruction that takes as an argument a class to operate
10 * on. Examples include <code>anewarray, checkcast, instance, anew</code>, etc.
11 *
12 * @author Abe White
13 */
14 public class ClassInstruction extends TypedInstruction {
15 private int _index = 0;
16
17 ClassInstruction(Code owner, int opcode) {
18 super(owner, opcode);
19 }
20
21 public int getStackChange() {
22 if (getOpcode() == Constants.NEW)
23 return 1;
24 return 0;
25 }
26
27 int getLength() {
28 return super.getLength() + 2;
29 }
30
31 /***
32 * Return the {@link ConstantPool} index of the
33 * {@link ClassEntry} describing the class for this instruction.
34 */
35 public int getTypeIndex() {
36 return _index;
37 }
38
39 /***
40 * Set the {@link ConstantPool} index of the
41 * {@link ClassEntry} describing the class for this instruction.
42 *
43 * @return this instruction, for method chaining
44 */
45 public ClassInstruction setTypeIndex(int index) {
46 _index = index;
47 return this;
48 }
49
50 public String getTypeName() {
51 if (_index == 0)
52 return null;
53
54 ClassEntry entry = (ClassEntry) getPool().getEntry(_index);
55 return getProject().getNameCache().getExternalForm(entry.
56 getNameEntry().getValue(), false);
57 }
58
59 public TypedInstruction setType(String type) {
60 if (type == null)
61 _index = 0;
62 else {
63 type = getProject().getNameCache().getInternalForm(type, false);
64 _index = getPool().findClassEntry(type, true);
65 }
66 return this;
67 }
68
69 /***
70 * ClassInstructions are equal if the type they reference is the same or
71 * unset and if their opcodes are equal.
72 */
73 public boolean equalsInstruction(Instruction other) {
74 if (other == this)
75 return true;
76 if (!super.equalsInstruction(other))
77 return false;
78
79 String type = getTypeName();
80 String otherType = ((ClassInstruction) other).getTypeName();
81 return (type == null) || (otherType == null) || type.equals(otherType);
82 }
83
84 public void acceptVisit(BCVisitor visit) {
85 visit.enterClassInstruction(this);
86 visit.exitClassInstruction(this);
87 }
88
89 void read(Instruction other) {
90 super.read(other);
91 setType(((ClassInstruction) other).getTypeName());
92 }
93
94 void read(DataInput in) throws IOException {
95 super.read(in);
96 _index = in.readUnsignedShort();
97 }
98
99 void write(DataOutput out) throws IOException {
100 super.write(out);
101 out.writeShort(_index);
102 }
103 }