1    /* 
2     * Javassist, a Java-bytecode translator toolkit. 
3     * Copyright (C) 1999-2003 Shigeru Chiba. All Rights Reserved. 
4     * 
5     * The contents of this file are subject to the Mozilla Public License Version 
6     * 1.1 (the "License"); you may not use this file except in compliance with 
7     * the License.  Alternatively, the contents of this file may be used under 
8     * the terms of the GNU Lesser General Public License Version 2.1 or later. 
9     * 
10    * Software distributed under the License is distributed on an "AS IS" basis, 
11    * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 
12    * for the specific language governing rights and limitations under the 
13    * License. 
14    */ 
15    
16   package javassist.bytecode; 
17    
18   import java.io.DataInputStream; 
19   import java.io.IOException; 
20   import java.util.Map; 
21    
22   /** 
23    * <code>LineNumberTablec_attribute</code>. 
24    */ 
25   public class LineNumberAttribute extends AttributeInfo { 
26       /** 
27        * The name of this attribute <code>"LineNumberTable"</code>. 
28        */ 
29       public static final String tag = "LineNumberTable"; 
30    
31       LineNumberAttribute(ConstPool cp, int n, DataInputStream in) 
32               throws IOException { 
33           super(cp, n, in); 
34       } 
35    
36       private LineNumberAttribute(ConstPool cp, byte[] i) { 
37           super(cp, tag, i); 
38       } 
39    
40       /** 
41        * Returns <code>line_number_table_length</code>. 
42        * This represents the number of entries in the table. 
43        */ 
44       public int tableLength() { 
45           return ByteArray.readU16bit(info, 0); 
46       } 
47    
48       /** 
49        * Returns <code>line_number_table[i].start_pc</code>. 
50        * This represents the index into the code array at which the code 
51        * for a new line in the original source file begins. 
52        * 
53        * @param i         the i-th entry. 
54        */ 
55       public int startPc(int i) { 
56           return ByteArray.readU16bit(info, i * 4 + 2); 
57       } 
58    
59       /** 
60        * Returns <code>line_number_table[i].line_number</code>. 
61        * This represents the corresponding line number in the original 
62        * source file. 
63        * 
64        * @param i         the i-th entry. 
65        */ 
66       public int lineNumber(int i) { 
67           return ByteArray.readU16bit(info, i * 4 + 4); 
68       } 
69    
70       /** 
71        * Returns the line number corresponding to the specified bytecode. 
72        * 
73        * @param pc        the index into the code array. 
74        */ 
75       public int toLineNumber(int pc) { 
76           int n = tableLength(); 
77           int i = 0; 
78           for (; i < n; ++i) 
79               if (pc < startPc(i)) 
80                   if (i == 0) 
81                       return lineNumber(0); 
82                   else 
83                       break; 
84    
85           return lineNumber(i - 1); 
86       } 
87    
88       /** 
89        * Returns the index into the code array at which the code for 
90        * the specified line begins. 
91        * 
92        * @param line      the line number. 
93        * @return          -1 if the specified line is not found. 
94        */ 
95       public int toStartPc(int line) { 
96           int n = tableLength(); 
97           for (int i = 0; i < n; ++i) 
98               if (line == lineNumber(i)) 
99                   return startPc(i); 
100   
101          return -1; 
102      } 
103   
104      /** 
105       * Makes a copy. 
106       * 
107       * @param newCp     the constant pool table used by the new copy. 
108       * @param classnames        should be null. 
109       */ 
110      public AttributeInfo copy(ConstPool newCp, Map classnames) { 
111          byte[] src = info; 
112          int num = src.length; 
113          byte[] dest = new byte[num]; 
114          for (int i = 0; i < num; ++i) 
115              dest[i] = src[i]; 
116   
117          LineNumberAttribute attr = new LineNumberAttribute(newCp, dest); 
118          return attr; 
119      } 
120  } 
121