    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;
    023import java.util.Arrays;
    024import java.util.Iterator;
    025import java.util.stream.Stream;
    026
    027import org.apache.bcel.Const;
    028
    029/**
    030 * This class represents colection of local variables in a method. This attribute is contained in the <em>Code</em>
    031 * attribute.
    032 *
    033 * @see Code
    034 * @see LocalVariable
    035 */
    036public class LocalVariableTable extends Attribute implements Iterable<LocalVariable> {
    037
    038    private LocalVariable[] localVariableTable; // variables
    039
    040    /**
    041     * Construct object from input stream.
    042     *
    043     * @param name_index Index in constant pool
    044     * @param length Content length in bytes
    045     * @param input Input stream
    046     * @param constant_pool Array of constants
    047     * @throws IOException if an I/O error occurs.
    048     */
    049    LocalVariableTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
    050        this(name_index, length, (LocalVariable[]) null, constant_pool);
    051        final int local_variable_table_length = input.readUnsignedShort();
    052        localVariableTable = new LocalVariable[local_variable_table_length];
    053        for (int i = 0; i < local_variable_table_length; i++) {
    054            localVariableTable[i] = new LocalVariable(input, constant_pool);
    055        }
    056    }
    057
    058    /**
    059     * @param nameIndex Index in constant pool to `LocalVariableTable'
    060     * @param length Content length in bytes
    061     * @param localVariableTable Table of local variables
    062     * @param constantPool Array of constants
    063     */
    064    public LocalVariableTable(final int nameIndex, final int length, final LocalVariable[] localVariableTable, final ConstantPool constantPool) {
    065        super(Const.ATTR_LOCAL_VARIABLE_TABLE, nameIndex, length, constantPool);
    066        this.localVariableTable = localVariableTable;
    067    }
    068
    069    /**
    070     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
    071     * physical copy.
    072     */
    073    public LocalVariableTable(final LocalVariableTable c) {
    074        this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool());
    075    }
    076
    077    /**
    078     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    079     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    080     *
    081     * @param v Visitor object
    082     */
    083    @Override
    084    public void accept(final Visitor v) {
    085        v.visitLocalVariableTable(this);
    086    }
    087
    088    /**
    089     * @return deep copy of this attribute
    090     */
    091    @Override
    092    public Attribute copy(final ConstantPool constantPool) {
    093        final LocalVariableTable c = (LocalVariableTable) clone();
    094        c.localVariableTable = new LocalVariable[localVariableTable.length];
    095        Arrays.setAll(c.localVariableTable, i -> localVariableTable[i].copy());
    096        c.setConstantPool(constantPool);
    097        return c;
    098    }
    099
    100    /**
    101     * Dump local variable table attribute to file stream in binary format.
    102     *
    103     * @param file Output file stream
    104     * @throws IOException if an I/O error occurs.
    105     */
    106    @Override
    107    public final void dump(final DataOutputStream file) throws IOException {
    108        super.dump(file);
    109        file.writeShort(localVariableTable.length);
    110        for (final LocalVariable variable : localVariableTable) {
    111            variable.dump(file);
    112        }
    113    }
    114
    115    /**
    116     *
    117     * @param index the variable slot
    118     *
    119     * @return the first LocalVariable that matches the slot or null if not found
    120     *
    121     * @deprecated since 5.2 because multiple variables can share the same slot, use getLocalVariable(int index, int pc)
    122     *             instead.
    123     */
    124    @java.lang.Deprecated
    125    public final LocalVariable getLocalVariable(final int index) {
    126        for (final LocalVariable variable : localVariableTable) {
    127            if (variable.getIndex() == index) {
    128                return variable;
    129            }
    130        }
    131        return null;
    132    }
    133
    134    /**
    135     *
    136     * @param index the variable slot
    137     * @param pc the current pc that this variable is alive
    138     *
    139     * @return the LocalVariable that matches or null if not found
    140     */
    141    public final LocalVariable getLocalVariable(final int index, final int pc) {
    142        for (final LocalVariable variable : localVariableTable) {
    143            if (variable.getIndex() == index) {
    144                final int start_pc = variable.getStartPC();
    145                final int end_pc = start_pc + variable.getLength();
    146                if (pc >= start_pc && pc <= end_pc) {
    147                    return variable;
    148                }
    149            }
    150        }
    151        return null;
    152    }
    153
    154    /**
    155     * @return Array of local variables of method.
    156     */
    157    public final LocalVariable[] getLocalVariableTable() {
    158        return localVariableTable;
    159    }
    160
    161    public final int getTableLength() {
    162        return localVariableTable == null ? 0 : localVariableTable.length;
    163    }
    164
    165    @Override
    166    public Iterator<LocalVariable> iterator() {
    167        return Stream.of(localVariableTable).iterator();
    168    }
    169
    170    public final void setLocalVariableTable(final LocalVariable[] local_variable_table) {
    171        this.localVariableTable = local_variable_table;
    172    }
    173
    174    /**
    175     * @return String representation.
    176     */
    177    @Override
    178    public final String toString() {
    179        final StringBuilder buf = new StringBuilder();
    180        for (int i = 0; i < localVariableTable.length; i++) {
    181            buf.append(localVariableTable[i]);
    182            if (i < localVariableTable.length - 1) {
    183                buf.append('\n');
    184            }
    185        }
    186        return buf.toString();
    187    }
    188}