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;
027import org.apache.bcel.util.Args;
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     * Constructs object from input stream.
042     *
043     * @param nameIndex Index in constant pool
044     * @param length Content length in bytes
045     * @param input Input stream
046     * @param constantPool Array of constants
047     * @throws IOException if an I/O error occurs.
048     */
049    LocalVariableTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
050        this(nameIndex, length, (LocalVariable[]) null, constantPool);
051        final int localVariableTableLength = input.readUnsignedShort();
052        localVariableTable = new LocalVariable[localVariableTableLength];
053        for (int i = 0; i < localVariableTableLength; i++) {
054            localVariableTable[i] = new LocalVariable(input, constantPool);
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 != null ? localVariableTable : LocalVariable.EMPTY_ARRAY;
067        Args.requireU2(this.localVariableTable.length, "localVariableTable.length");
068    }
069
070    /**
071     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
072     * physical copy.
073     *
074     * @param c Source to copy.
075     */
076    public LocalVariableTable(final LocalVariableTable c) {
077        this(c.getNameIndex(), c.getLength(), c.getLocalVariableTable(), c.getConstantPool());
078    }
079
080    /**
081     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
082     * I.e., the hierarchy of methods, 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     * @return deep copy of this attribute
093     */
094    @Override
095    public Attribute copy(final ConstantPool constantPool) {
096        final LocalVariableTable c = (LocalVariableTable) clone();
097        c.localVariableTable = new LocalVariable[localVariableTable.length];
098        Arrays.setAll(c.localVariableTable, i -> localVariableTable[i].copy());
099        c.setConstantPool(constantPool);
100        return c;
101    }
102
103    /**
104     * Dump local variable table attribute to file stream in binary format.
105     *
106     * @param file Output file stream
107     * @throws IOException if an I/O error occurs.
108     */
109    @Override
110    public final void dump(final DataOutputStream file) throws IOException {
111        super.dump(file);
112        file.writeShort(localVariableTable.length);
113        for (final LocalVariable variable : localVariableTable) {
114            variable.dump(file);
115        }
116    }
117
118    /**
119     *
120     * @param index the variable slot
121     *
122     * @return the first LocalVariable that matches the slot or null if not found
123     *
124     * @deprecated since 5.2 because multiple variables can share the same slot, use getLocalVariable(int index, int pc)
125     *             instead.
126     */
127    @java.lang.Deprecated
128    public final LocalVariable getLocalVariable(final int index) {
129        for (final LocalVariable variable : localVariableTable) {
130            if (variable.getIndex() == index) {
131                return variable;
132            }
133        }
134        return null;
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 : localVariableTable) {
146            if (variable.getIndex() == index) {
147                final int startPc = variable.getStartPC();
148                final int endPc = startPc + variable.getLength();
149                if (pc >= startPc && pc <= endPc) {
150                    return variable;
151                }
152            }
153        }
154        return null;
155    }
156
157    /**
158     * @return Array of local variables of method.
159     */
160    public final LocalVariable[] getLocalVariableTable() {
161        return localVariableTable;
162    }
163
164    public final int getTableLength() {
165        return localVariableTable == null ? 0 : localVariableTable.length;
166    }
167
168    @Override
169    public Iterator<LocalVariable> iterator() {
170        return Stream.of(localVariableTable).iterator();
171    }
172
173    public final void setLocalVariableTable(final LocalVariable[] localVariableTable) {
174        this.localVariableTable = localVariableTable;
175    }
176
177    /**
178     * @return String representation.
179     */
180    @Override
181    public final String toString() {
182        final StringBuilder buf = new StringBuilder();
183        for (int i = 0; i < localVariableTable.length; i++) {
184            buf.append(localVariableTable[i]);
185            if (i < localVariableTable.length - 1) {
186                buf.append('\n');
187            }
188        }
189        return buf.toString();
190    }
191}