1 /* 2 * Javassist, a Java-bytecode translator toolkit. 3 * Copyright (C) 1999-2007 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>LineNumberTable_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 LineNumberAttribute(ConstPool cp, int n, DataInputStream in)31 LineNumberAttribute(ConstPool cp, int n, DataInputStream in) 32 throws IOException 33 { 34 super(cp, n, in); 35 } 36 LineNumberAttribute(ConstPool cp, byte[] i)37 private LineNumberAttribute(ConstPool cp, byte[] i) { 38 super(cp, tag, i); 39 } 40 41 /** 42 * Returns <code>line_number_table_length</code>. 43 * This represents the number of entries in the table. 44 */ tableLength()45 public int tableLength() { 46 return ByteArray.readU16bit(info, 0); 47 } 48 49 /** 50 * Returns <code>line_number_table[i].start_pc</code>. 51 * This represents the index into the code array at which the code 52 * for a new line in the original source file begins. 53 * 54 * @param i the i-th entry. 55 */ startPc(int i)56 public int startPc(int i) { 57 return ByteArray.readU16bit(info, i * 4 + 2); 58 } 59 60 /** 61 * Returns <code>line_number_table[i].line_number</code>. 62 * This represents the corresponding line number in the original 63 * source file. 64 * 65 * @param i the i-th entry. 66 */ lineNumber(int i)67 public int lineNumber(int i) { 68 return ByteArray.readU16bit(info, i * 4 + 4); 69 } 70 71 /** 72 * Returns the line number corresponding to the specified bytecode. 73 * 74 * @param pc the index into the code array. 75 */ toLineNumber(int pc)76 public int toLineNumber(int pc) { 77 int n = tableLength(); 78 int i = 0; 79 for (; i < n; ++i) 80 if (pc < startPc(i)) 81 if (i == 0) 82 return lineNumber(0); 83 else 84 break; 85 86 return lineNumber(i - 1); 87 } 88 89 /** 90 * Returns the index into the code array at which the code for 91 * the specified line begins. 92 * 93 * @param line the line number. 94 * @return -1 if the specified line is not found. 95 */ toStartPc(int line)96 public int toStartPc(int line) { 97 int n = tableLength(); 98 for (int i = 0; i < n; ++i) 99 if (line == lineNumber(i)) 100 return startPc(i); 101 102 return -1; 103 } 104 105 /** 106 * Used as a return type of <code>toNearPc()</code>. 107 */ 108 static public class Pc { 109 /** 110 * The index into the code array. 111 */ 112 public int index; 113 /** 114 * The line number. 115 */ 116 public int line; 117 } 118 119 /** 120 * Returns the index into the code array at which the code for 121 * the specified line (or the nearest line after the specified one) 122 * begins. 123 * 124 * @param line the line number. 125 * @return a pair of the index and the line number of the 126 * bytecode at that index. 127 */ toNearPc(int line)128 public Pc toNearPc(int line) { 129 int n = tableLength(); 130 int nearPc = 0; 131 int distance = 0; 132 if (n > 0) { 133 distance = lineNumber(0) - line; 134 nearPc = startPc(0); 135 } 136 137 for (int i = 1; i < n; ++i) { 138 int d = lineNumber(i) - line; 139 if ((d < 0 && d > distance) 140 || (d >= 0 && (d < distance || distance < 0))) { 141 distance = d; 142 nearPc = startPc(i); 143 } 144 } 145 146 Pc res = new Pc(); 147 res.index = nearPc; 148 res.line = line + distance; 149 return res; 150 } 151 152 /** 153 * Makes a copy. 154 * 155 * @param newCp the constant pool table used by the new copy. 156 * @param classnames should be null. 157 */ copy(ConstPool newCp, Map classnames)158 public AttributeInfo copy(ConstPool newCp, Map classnames) { 159 byte[] src = info; 160 int num = src.length; 161 byte[] dest = new byte[num]; 162 for (int i = 0; i < num; ++i) 163 dest[i] = src[i]; 164 165 LineNumberAttribute attr = new LineNumberAttribute(newCp, dest); 166 return attr; 167 } 168 169 /** 170 * Adjusts start_pc if bytecode is inserted in a method body. 171 */ shiftPc(int where, int gapLength, boolean exclusive)172 void shiftPc(int where, int gapLength, boolean exclusive) { 173 int n = tableLength(); 174 for (int i = 0; i < n; ++i) { 175 int pos = i * 4 + 2; 176 int pc = ByteArray.readU16bit(info, pos); 177 if (pc > where || (exclusive && pc == where)) 178 ByteArray.write16bit(pc + gapLength, info, pos); 179 } 180 } 181 } 182