1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.bcel.classfile;
18
19 import java.io.DataInput;
20 import java.io.DataOutputStream;
21 import java.io.IOException;
22
23 import org.apache.bcel.util.Args;
24
25 /**
26 * This class represents a (PC offset, line number) pair, i.e., a line number in the source that corresponds to a
27 * relative address in the byte code. This is used for debugging purposes.
28 *
29 * @see LineNumberTable
30 */
31 public final class LineNumber implements Cloneable, Node {
32
33 static final LineNumber[] EMPTY_ARRAY = {};
34
35 /** Program Counter (PC) corresponds to line */
36 private int startPc;
37
38 /** Number in source file */
39 private int lineNumber;
40
41 /**
42 * Constructs object from file stream.
43 *
44 * @param file Input stream
45 * @throws IOException if an I/O Exception occurs in readUnsignedShort
46 */
47 LineNumber(final DataInput file) throws IOException {
48 this(file.readUnsignedShort(), file.readUnsignedShort());
49 }
50
51 /**
52 * @param startPc Program Counter (PC) corresponds to
53 * @param lineNumber line number in source file
54 */
55 public LineNumber(final int startPc, final int lineNumber) {
56 this.startPc = Args.requireU2(startPc, "startPc");
57 this.lineNumber = Args.requireU2(lineNumber, "lineNumber");
58 }
59
60 /**
61 * Initialize from another object.
62 *
63 * @param c the object to copy
64 */
65 public LineNumber(final LineNumber c) {
66 this(c.getStartPC(), c.getLineNumber());
67 }
68
69 /**
70 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
71 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
72 *
73 * @param v Visitor object
74 */
75 @Override
76 public void accept(final Visitor v) {
77 v.visitLineNumber(this);
78 }
79
80 /**
81 * @return deep copy of this object
82 */
83 public LineNumber copy() {
84 try {
85 return (LineNumber) clone();
86 } catch (final CloneNotSupportedException e) {
87 // TODO should this throw?
88 }
89 return null;
90 }
91
92 /**
93 * Dump line number/pc pair to file stream in binary format.
94 *
95 * @param file Output file stream
96 * @throws IOException if an I/O Exception occurs in writeShort
97 */
98 public void dump(final DataOutputStream file) throws IOException {
99 file.writeShort(startPc);
100 file.writeShort(lineNumber);
101 }
102
103 /**
104 * @return Corresponding source line
105 */
106 public int getLineNumber() {
107 return lineNumber & 0xffff;
108 }
109
110 /**
111 * @return PC in code
112 */
113 public int getStartPC() {
114 return startPc & 0xffff;
115 }
116
117 /**
118 * @param lineNumber the source line number
119 */
120 public void setLineNumber(final int lineNumber) {
121 this.lineNumber = (short) lineNumber;
122 }
123
124 /**
125 * @param startPc the pc for this line number
126 */
127 public void setStartPC(final int startPc) {
128 this.startPc = (short) startPc;
129 }
130
131 /**
132 * @return String representation
133 */
134 @Override
135 public String toString() {
136 return "LineNumber(" + getStartPC() + ", " + getLineNumber() + ")";
137 }
138 }