Source code

    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 */
    017package org.apache.bcel.classfile;
    018
    019import java.io.DataInput;
    020import java.io.DataOutputStream;
    021import java.io.IOException;
    022import java.util.Arrays;
    023import java.util.Iterator;
    024import java.util.stream.Stream;
    025
    026import org.apache.bcel.Const;
    027
    028/**
    029 * This class represents colection of local variables in a method. This attribute is contained in the <em>Code</em>
    030 * attribute.
    031 *
    032 * @see Code
    033 * @see LocalVariable
    034 */
    035public class LocalVariableTable extends Attribute implements Iterable<LocalVariable> {
    036
    037    private LocalVariable[] localVariableTable; // variables
    038
    039    /**
    040     * Construct object from input stream.
    041     *
    042     * @param nameIndex Index in constant pool
    043     * @param length Content length in bytes
    044     * @param input Input stream
    045     * @param constantPool Array of constants
    046     * @throws IOException if an I/O error occurs.
    047     */
    048    LocalVariableTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
    049        this(nameIndex, length, (LocalVariable[]) null, constantPool);
    050        final int localVariableTableLength = input.readUnsignedShort();
    051        localVariableTable = new LocalVariable[localVariableTableLength];
    052        for (int i = 0; i < localVariableTableLength; i++) {
    053            localVariableTable[i] = new LocalVariable(input, constantPool);
    054        }
    055    }
    056
    057    /**
    058     * @param nameIndex Index in constant pool to `LocalVariableTable'
    059     * @param length Content length in bytes
    060     * @param localVariableTable Table of local variables
    061     * @param constantPool Array of constants
    062     */
    063    public LocalVariableTable(final int nameIndex, final int length, final LocalVariable[] localVariableTable, final ConstantPool constantPool) {
    064        super(Const.ATTR_LOCAL_VARIABLE_TABLE, nameIndex, length, constantPool);
    065        this.localVariableTable = localVariableTable;
    066    }
    067
    068    /**
    069     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
    070     * physical copy.
    071     */
    072    public LocalVariableTable(final LocalVariableTable c) {
    073        this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool());
    074    }
    075
    076    /**
    077     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    078     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    079     *
    080     * @param v Visitor object
    081     */
    082    @Override
    083    public void accept(final Visitor v) {
    084        v.visitLocalVariableTable(this);
    085    }
    086
    087    /**
    088     * @return deep copy of this attribute
    089     */
    090    @Override
    091    public Attribute copy(final ConstantPool constantPool) {
    092        final LocalVariableTable c = (LocalVariableTable) clone();
    093        c.localVariableTable = new LocalVariable[localVariableTable.length];
    094        Arrays.setAll(c.localVariableTable, i -> localVariableTable[i].copy());
    095        c.setConstantPool(constantPool);
    096        return c;
    097    }
    098
    099    /**
    100     * Dump local variable table attribute to file stream in binary format.
    101     *
    102     * @param file Output file stream
    103     * @throws IOException if an I/O error occurs.
    104     */
    105    @Override
    106    public final void dump(final DataOutputStream file) throws IOException {
    107        super.dump(file);
    108        file.writeShort(localVariableTable.length);
    109        for (final LocalVariable variable : localVariableTable) {
    110            variable.dump(file);
    111        }
    112    }
    113
    114    /**
    115     *
    116     * @param index the variable slot
    117     *
    118     * @return the first LocalVariable that matches the slot or null if not found
    119     *
    120     * @deprecated since 5.2 because multiple variables can share the same slot, use getLocalVariable(int index, int pc)
    121     *             instead.
    122     */
    123    @java.lang.Deprecated
    124    public final LocalVariable getLocalVariable(final int index) {
    125        for (final LocalVariable variable : localVariableTable) {
    126            if (variable.getIndex() == index) {
    127                return variable;
    128            }
    129        }
    130        return null;
    131    }
    132
    133    /**
    134     *
    135     * @param index the variable slot
    136     * @param pc the current pc that this variable is alive
    137     *
    138     * @return the LocalVariable that matches or null if not found
    139     */
    140    public final LocalVariable getLocalVariable(final int index, final int pc) {
    141        for (final LocalVariable variable : localVariableTable) {
    142            if (variable.getIndex() == index) {
    143                final int startPc = variable.getStartPC();
    144                final int endPc = startPc + variable.getLength();
    145                if (pc >= startPc && pc <= endPc) {
    146                    return variable;
    147                }
    148            }
    149        }
    150        return null;
    151    }
    152
    153    /**
    154     * @return Array of local variables of method.
    155     */
    156    public final LocalVariable[] getLocalVariableTable() {
    157        return localVariableTable;
    158    }
    159
    160    public final int getTableLength() {
    161        return localVariableTable == null ? 0 : localVariableTable.length;
    162    }
    163
    164    @Override
    165    public Iterator<LocalVariable> iterator() {
    166        return Stream.of(localVariableTable).iterator();
    167    }
    168
    169    public final void setLocalVariableTable(final LocalVariable[] localVariableTable) {
    170        this.localVariableTable = localVariableTable;
    171    }
    172
    173    /**
    174     * @return String representation.
    175     */
    176    @Override
    177    public final String toString() {
    178        final StringBuilder buf = new StringBuilder();
    179        for (int i = 0; i < localVariableTable.length; i++) {
    180            buf.append(localVariableTable[i]);
    181            if (i < localVariableTable.length - 1) {
    182                buf.append('\n');
    183            }
    184        }
    185        return buf.toString();
    186    }
    187}