    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 * @version $Id$
    031 * @see     Code
    032 * @see LocalVariable
    033 */
    034public class LocalVariableTable extends Attribute {
    035
    036    private LocalVariable[] local_variable_table; // variables
    037
    038
    039    /**
    040     * Initialize from another object. Note that both objects use the same
    041     * references (shallow copy). Use copy() for a physical copy.
    042     */
    043    public LocalVariableTable(final LocalVariableTable c) {
    044        this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool());
    045    }
    046
    047
    048    /**
    049     * @param name_index Index in constant pool to `LocalVariableTable'
    050     * @param length Content length in bytes
    051     * @param local_variable_table Table of local variables
    052     * @param constant_pool Array of constants
    053     */
    054    public LocalVariableTable(final int name_index, final int length, final LocalVariable[] local_variable_table,
    055            final ConstantPool constant_pool) {
    056        super(Const.ATTR_LOCAL_VARIABLE_TABLE, name_index, length, constant_pool);
    057        this.local_variable_table = local_variable_table;
    058    }
    059
    060
    061    /**
    062     * Construct object from input stream.
    063     * @param name_index Index in constant pool
    064     * @param length Content length in bytes
    065     * @param input Input stream
    066     * @param constant_pool Array of constants
    067     * @throws IOException
    068     */
    069    LocalVariableTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)
    070            throws IOException {
    071        this(name_index, length, (LocalVariable[]) null, constant_pool);
    072        final int local_variable_table_length = input.readUnsignedShort();
    073        local_variable_table = new LocalVariable[local_variable_table_length];
    074        for (int i = 0; i < local_variable_table_length; i++) {
    075            local_variable_table[i] = new LocalVariable(input, constant_pool);
    076        }
    077    }
    078
    079
    080    /**
    081     * Called by objects that are traversing the nodes of the tree implicitely
    082     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    083     * fields, attributes, etc. spawns a tree of objects.
    084     *
    085     * @param v Visitor object
    086     */
    087    @Override
    088    public void accept( final Visitor v ) {
    089        v.visitLocalVariableTable(this);
    090    }
    091
    092
    093    /**
    094     * Dump local variable table attribute to file stream in binary format.
    095     *
    096     * @param file Output file stream
    097     * @throws IOException
    098     */
    099    @Override
    100    public final void dump( final DataOutputStream file ) throws IOException {
    101        super.dump(file);
    102        file.writeShort(local_variable_table.length);
    103        for (final LocalVariable variable : local_variable_table) {
    104            variable.dump(file);
    105        }
    106    }
    107
    108
    109    /**
    110     * @return Array of local variables of method.
    111     */
    112    public final LocalVariable[] getLocalVariableTable() {
    113        return local_variable_table;
    114    }
    115
    116
    117    /**
    118     *
    119     * @param index the variable slot
    120     *
    121     * @return the first LocalVariable that matches the slot or null if not found
    122     *
    123     * @deprecated since 5.2 because multiple variables can share the
    124     *             same slot, use getLocalVariable(int index, int pc) instead.
    125     */
    126    @java.lang.Deprecated
    127    public final LocalVariable getLocalVariable( final int index ) {
    128        for (final LocalVariable variable : local_variable_table) {
    129            if (variable.getIndex() == index) {
    130                return variable;
    131            }
    132        }
    133        return null;
    134    }
    135
    136
    137    /**
    138     *
    139     * @param index the variable slot
    140     * @param pc the current pc that this variable is alive
    141     *
    142     * @return the LocalVariable that matches or null if not found
    143     */
    144    public final LocalVariable getLocalVariable( final int index, final int pc ) {
    145        for (final LocalVariable variable : local_variable_table) {
    146            if (variable.getIndex() == index) {
    147                final int start_pc = variable.getStartPC();
    148                final int end_pc = start_pc + variable.getLength();
    149                if ((pc >= start_pc) && (pc <= end_pc)) {
    150                    return variable;
    151                }
    152            }
    153        }
    154        return null;
    155    }
    156
    157
    158    public final void setLocalVariableTable( final LocalVariable[] local_variable_table ) {
    159        this.local_variable_table = local_variable_table;
    160    }
    161
    162
    163    /**
    164     * @return String representation.
    165     */
    166    @Override
    167    public final String toString() {
    168        final StringBuilder buf = new StringBuilder();
    169        for (int i = 0; i < local_variable_table.length; i++) {
    170            buf.append(local_variable_table[i]);
    171            if (i < local_variable_table.length - 1) {
    172                buf.append('\n');
    173            }
    174        }
    175        return buf.toString();
    176    }
    177
    178
    179    /**
    180     * @return deep copy of this attribute
    181     */
    182    @Override
    183    public Attribute copy( final ConstantPool _constant_pool ) {
    184        final LocalVariableTable c = (LocalVariableTable) clone();
    185        c.local_variable_table = new LocalVariable[local_variable_table.length];
    186        for (int i = 0; i < local_variable_table.length; i++) {
    187            c.local_variable_table[i] = local_variable_table[i].copy();
    188        }
    189        c.setConstantPool(_constant_pool);
    190        return c;
    191    }
    192
    193
    194    public final int getTableLength() {
    195        return local_variable_table == null ? 0 : local_variable_table.length;
    196    }
    197}