001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018package org.apache.bcel.classfile; 019 020import java.io.DataInput; 021import java.io.DataOutputStream; 022import java.io.IOException; 023 024import org.apache.bcel.Const; 025 026/** 027 * This class represents a table of line numbers for debugging 028 * purposes. This attribute is used by the <em>Code</em> attribute. It 029 * contains pairs of PCs and line numbers. 030 * 031 * @see Code 032 * @see LineNumber 033 */ 034public final class LineNumberTable extends Attribute { 035 036 private static final int MAX_LINE_LENGTH = 72; 037 private LineNumber[] line_number_table; // Table of line/numbers pairs 038 039 040 /* 041 * Initialize from another object. Note that both objects use the same 042 * references (shallow copy). Use copy() for a physical copy. 043 */ 044 public LineNumberTable(final LineNumberTable c) { 045 this(c.getNameIndex(), c.getLength(), c.getLineNumberTable(), c.getConstantPool()); 046 } 047 048 049 /* 050 * @param name_index Index of name 051 * @param length Content length in bytes 052 * @param line_number_table Table of line/numbers pairs 053 * @param constant_pool Array of constants 054 */ 055 public LineNumberTable(final int name_index, final int length, final LineNumber[] line_number_table, 056 final ConstantPool constant_pool) { 057 super(Const.ATTR_LINE_NUMBER_TABLE, name_index, length, constant_pool); 058 this.line_number_table = line_number_table; 059 } 060 061 062 /** 063 * Construct object from input stream. 064 * @param name_index Index of name 065 * @param length Content length in bytes 066 * @param input Input stream 067 * @param constant_pool Array of constants 068 * @throws IOException if an I/O Exception occurs in readUnsignedShort 069 */ 070 LineNumberTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) 071 throws IOException { 072 this(name_index, length, (LineNumber[]) null, constant_pool); 073 final int line_number_table_length = input.readUnsignedShort(); 074 line_number_table = new LineNumber[line_number_table_length]; 075 for (int i = 0; i < line_number_table_length; i++) { 076 line_number_table[i] = new LineNumber(input); 077 } 078 } 079 080 081 /** 082 * Called by objects that are traversing the nodes of the tree implicitely 083 * defined by the contents of a Java class. I.e., the hierarchy of methods, 084 * fields, attributes, etc. spawns a tree of objects. 085 * 086 * @param v Visitor object 087 */ 088 @Override 089 public void accept( final Visitor v ) { 090 v.visitLineNumberTable(this); 091 } 092 093 094 /** 095 * Dump line number table attribute to file stream in binary format. 096 * 097 * @param file Output file stream 098 * @throws IOException if an I/O Exception occurs in writeShort 099 */ 100 @Override 101 public void dump( final DataOutputStream file ) throws IOException { 102 super.dump(file); 103 file.writeShort(line_number_table.length); 104 for (final LineNumber lineNumber : line_number_table) { 105 lineNumber.dump(file); 106 } 107 } 108 109 110 /** 111 * @return Array of (pc offset, line number) pairs. 112 */ 113 public LineNumber[] getLineNumberTable() { 114 return line_number_table; 115 } 116 117 118 /** 119 * @param line_number_table the line number entries for this table 120 */ 121 public void setLineNumberTable( final LineNumber[] line_number_table ) { 122 this.line_number_table = line_number_table; 123 } 124 125 126 /** 127 * @return String representation. 128 */ 129 @Override 130 public String toString() { 131 final StringBuilder buf = new StringBuilder(); 132 final StringBuilder line = new StringBuilder(); 133 final String newLine = System.getProperty("line.separator", "\n"); 134 for (int i = 0; i < line_number_table.length; i++) { 135 line.append(line_number_table[i].toString()); 136 if (i < line_number_table.length - 1) { 137 line.append(", "); 138 } 139 if ((line.length() > MAX_LINE_LENGTH) && (i < line_number_table.length - 1)) { 140 line.append(newLine); 141 buf.append(line); 142 line.setLength(0); 143 } 144 } 145 buf.append(line); 146 return buf.toString(); 147 } 148 149 150 /** 151 * Map byte code positions to source code lines. 152 * 153 * @param pos byte code offset 154 * @return corresponding line in source code 155 */ 156 public int getSourceLine( final int pos ) { 157 int l = 0; 158 int r = line_number_table.length - 1; 159 if (r < 0) { 160 return -1; 161 } 162 int min_index = -1; 163 int min = -1; 164 /* Do a binary search since the array is ordered. 165 */ 166 do { 167 final int i = (l + r) >>> 1; 168 final int j = line_number_table[i].getStartPC(); 169 if (j == pos) { 170 return line_number_table[i].getLineNumber(); 171 } else if (pos < j) { 172 r = i - 1; 173 } else { 174 l = i + 1; 175 } 176 /* If exact match can't be found (which is the most common case) 177 * return the line number that corresponds to the greatest index less 178 * than pos. 179 */ 180 if (j < pos && j > min) { 181 min = j; 182 min_index = i; 183 } 184 } while (l <= r); 185 /* It's possible that we did not find any valid entry for the bytecode 186 * offset we were looking for. 187 */ 188 if (min_index < 0) { 189 return -1; 190 } 191 return line_number_table[min_index].getLineNumber(); 192 } 193 194 195 /** 196 * @return deep copy of this attribute 197 */ 198 @Override 199 public Attribute copy( final ConstantPool _constant_pool ) { 200 // TODO could use the lower level constructor and thereby allow 201 // line_number_table to be made final 202 final LineNumberTable c = (LineNumberTable) clone(); 203 c.line_number_table = new LineNumber[line_number_table.length]; 204 for (int i = 0; i < line_number_table.length; i++) { 205 c.line_number_table[i] = line_number_table[i].copy(); 206 } 207 c.setConstantPool(_constant_pool); 208 return c; 209 } 210 211 212 public int getTableLength() { 213 return line_number_table == null ? 0 : line_number_table.length; 214 } 215}