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}