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}