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 colection of local variables in a 028 * method. This attribute is contained in the <em>Code</em> attribute. 029 * 030 * @see Code 031 * @see LocalVariable 032 */ 033public class LocalVariableTable extends Attribute { 034 035 private LocalVariable[] local_variable_table; // variables 036 037 038 /** 039 * Initialize from another object. Note that both objects use the same 040 * references (shallow copy). Use copy() for a physical copy. 041 */ 042 public LocalVariableTable(final LocalVariableTable c) { 043 this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool()); 044 } 045 046 047 /** 048 * @param name_index Index in constant pool to `LocalVariableTable' 049 * @param length Content length in bytes 050 * @param local_variable_table Table of local variables 051 * @param constant_pool Array of constants 052 */ 053 public LocalVariableTable(final int name_index, final int length, final LocalVariable[] local_variable_table, 054 final ConstantPool constant_pool) { 055 super(Const.ATTR_LOCAL_VARIABLE_TABLE, name_index, length, constant_pool); 056 this.local_variable_table = local_variable_table; 057 } 058 059 060 /** 061 * Construct object from input stream. 062 * @param name_index Index in constant pool 063 * @param length Content length in bytes 064 * @param input Input stream 065 * @param constant_pool Array of constants 066 * @throws IOException 067 */ 068 LocalVariableTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) 069 throws IOException { 070 this(name_index, length, (LocalVariable[]) null, constant_pool); 071 final int local_variable_table_length = input.readUnsignedShort(); 072 local_variable_table = new LocalVariable[local_variable_table_length]; 073 for (int i = 0; i < local_variable_table_length; i++) { 074 local_variable_table[i] = new LocalVariable(input, constant_pool); 075 } 076 } 077 078 079 /** 080 * Called by objects that are traversing the nodes of the tree implicitely 081 * defined by the contents of a Java class. I.e., the hierarchy of methods, 082 * fields, attributes, etc. spawns a tree of objects. 083 * 084 * @param v Visitor object 085 */ 086 @Override 087 public void accept( final Visitor v ) { 088 v.visitLocalVariableTable(this); 089 } 090 091 092 /** 093 * Dump local variable table attribute to file stream in binary format. 094 * 095 * @param file Output file stream 096 * @throws IOException 097 */ 098 @Override 099 public final void dump( final DataOutputStream file ) throws IOException { 100 super.dump(file); 101 file.writeShort(local_variable_table.length); 102 for (final LocalVariable variable : local_variable_table) { 103 variable.dump(file); 104 } 105 } 106 107 108 /** 109 * @return Array of local variables of method. 110 */ 111 public final LocalVariable[] getLocalVariableTable() { 112 return local_variable_table; 113 } 114 115 116 /** 117 * 118 * @param index the variable slot 119 * 120 * @return the first LocalVariable that matches the slot or null if not found 121 * 122 * @deprecated since 5.2 because multiple variables can share the 123 * same slot, use getLocalVariable(int index, int pc) instead. 124 */ 125 @java.lang.Deprecated 126 public final LocalVariable getLocalVariable( final int index ) { 127 for (final LocalVariable variable : local_variable_table) { 128 if (variable.getIndex() == index) { 129 return variable; 130 } 131 } 132 return null; 133 } 134 135 136 /** 137 * 138 * @param index the variable slot 139 * @param pc the current pc that this variable is alive 140 * 141 * @return the LocalVariable that matches or null if not found 142 */ 143 public final LocalVariable getLocalVariable( final int index, final int pc ) { 144 for (final LocalVariable variable : local_variable_table) { 145 if (variable.getIndex() == index) { 146 final int start_pc = variable.getStartPC(); 147 final int end_pc = start_pc + variable.getLength(); 148 if ((pc >= start_pc) && (pc <= end_pc)) { 149 return variable; 150 } 151 } 152 } 153 return null; 154 } 155 156 157 public final void setLocalVariableTable( final LocalVariable[] local_variable_table ) { 158 this.local_variable_table = local_variable_table; 159 } 160 161 162 /** 163 * @return String representation. 164 */ 165 @Override 166 public final String toString() { 167 final StringBuilder buf = new StringBuilder(); 168 for (int i = 0; i < local_variable_table.length; i++) { 169 buf.append(local_variable_table[i]); 170 if (i < local_variable_table.length - 1) { 171 buf.append('\n'); 172 } 173 } 174 return buf.toString(); 175 } 176 177 178 /** 179 * @return deep copy of this attribute 180 */ 181 @Override 182 public Attribute copy( final ConstantPool _constant_pool ) { 183 final LocalVariableTable c = (LocalVariableTable) clone(); 184 c.local_variable_table = new LocalVariable[local_variable_table.length]; 185 for (int i = 0; i < local_variable_table.length; i++) { 186 c.local_variable_table[i] = local_variable_table[i].copy(); 187 } 188 c.setConstantPool(_constant_pool); 189 return c; 190 } 191 192 193 public final int getTableLength() { 194 return local_variable_table == null ? 0 : local_variable_table.length; 195 } 196}