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;
025import org.apache.bcel.Constants;
026
027/**
028 * This class represents a local variable within a method. It contains its
029 * scope, name, signature and index on the method's frame.
030 *
031 * @version $Id: LocalVariable.java 1749603 2016-06-21 20:50:19Z ggregory $
032 * @see     LocalVariableTable
033 */
034public final class LocalVariable implements Cloneable, Node, Constants {
035
036    private int start_pc; // Range in which the variable is valid
037    private int length;
038    private int name_index; // Index in constant pool of variable name
039    private int signature_index; // Index of variable signature
040    private int index; /* Variable is `index'th local variable on
041     * this method's frame.
042     */
043    private ConstantPool constant_pool;
044
045
046    /**
047     * Initialize from another object. Note that both objects use the same
048     * references (shallow copy). Use copy() for a physical copy.
049     */
050    public LocalVariable(final LocalVariable c) {
051        this(c.getStartPC(), c.getLength(), c.getNameIndex(), c.getSignatureIndex(), c.getIndex(),
052                c.getConstantPool());
053    }
054
055
056    /**
057     * Construct object from file stream.
058     * @param file Input stream
059     * @throws IOException
060     */
061    LocalVariable(final DataInput file, final ConstantPool constant_pool) throws IOException {
062        this(file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file
063                .readUnsignedShort(), file.readUnsignedShort(), constant_pool);
064    }
065
066
067    /**
068     * @param start_pc Range in which the variable
069     * @param length ... is valid
070     * @param name_index Index in constant pool of variable name
071     * @param signature_index Index of variable's signature
072     * @param index Variable is `index'th local variable on the method's frame
073     * @param constant_pool Array of constants
074     */
075    public LocalVariable(final int start_pc, final int length, final int name_index, final int signature_index, final int index,
076            final ConstantPool constant_pool) {
077        this.start_pc = start_pc;
078        this.length = length;
079        this.name_index = name_index;
080        this.signature_index = signature_index;
081        this.index = index;
082        this.constant_pool = constant_pool;
083    }
084
085
086    /**
087     * Called by objects that are traversing the nodes of the tree implicitely
088     * defined by the contents of a Java class. I.e., the hierarchy of methods,
089     * fields, attributes, etc. spawns a tree of objects.
090     *
091     * @param v Visitor object
092     */
093    @Override
094    public void accept( final Visitor v ) {
095        v.visitLocalVariable(this);
096    }
097
098
099    /**
100     * Dump local variable to file stream in binary format.
101     *
102     * @param file Output file stream
103     * @throws IOException
104     */
105    public final void dump( final DataOutputStream file ) throws IOException {
106        file.writeShort(start_pc);
107        file.writeShort(length);
108        file.writeShort(name_index);
109        file.writeShort(signature_index);
110        file.writeShort(index);
111    }
112
113
114    /**
115     * @return Constant pool used by this object.
116     */
117    public final ConstantPool getConstantPool() {
118        return constant_pool;
119    }
120
121
122    /**
123     * @return Variable is valid within getStartPC() .. getStartPC()+getLength()
124     */
125    public final int getLength() {
126        return length;
127    }
128
129
130    /**
131     * @return Variable name.
132     */
133    public final String getName() {
134        ConstantUtf8 c;
135        c = (ConstantUtf8) constant_pool.getConstant(name_index, Const.CONSTANT_Utf8);
136        return c.getBytes();
137    }
138
139
140    /**
141     * @return Index in constant pool of variable name.
142     */
143    public final int getNameIndex() {
144        return name_index;
145    }
146
147
148    /**
149     * @return Signature.
150     */
151    public final String getSignature() {
152        ConstantUtf8 c;
153        c = (ConstantUtf8) constant_pool.getConstant(signature_index, Const.CONSTANT_Utf8);
154        return c.getBytes();
155    }
156
157
158    /**
159     * @return Index in constant pool of variable signature.
160     */
161    public final int getSignatureIndex() {
162        return signature_index;
163    }
164
165
166    /**
167     * @return index of register where variable is stored
168     */
169    public final int getIndex() {
170        return index;
171    }
172
173
174    /**
175     * @return Start of range where he variable is valid
176     */
177    public final int getStartPC() {
178        return start_pc;
179    }
180
181
182    /*
183     * Helper method shared with LocalVariableTypeTable
184     */
185    final String toStringShared( final boolean typeTable ) {
186        final String name = getName();
187        final String signature = Utility.signatureToString(getSignature(), false);
188        final String label = "LocalVariable" + (typeTable ? "Types" : "" );
189        return label + "(start_pc = " + start_pc + ", length = " + length + ", index = "
190                + index + ":" + signature + " " + name + ")";
191    }
192
193
194    /**
195     * @param constant_pool Constant pool to be used for this object.
196     */
197    public final void setConstantPool( final ConstantPool constant_pool ) {
198        this.constant_pool = constant_pool;
199    }
200
201
202    /**
203     * @param length the length of this local variable
204     */
205    public final void setLength( final int length ) {
206        this.length = length;
207    }
208
209
210    /**
211     * @param name_index the index into the constant pool for the name of this variable
212     */
213    public final void setNameIndex( final int name_index ) { // TODO unused
214        this.name_index = name_index;
215    }
216
217
218    /**
219     * @param signature_index the index into the constant pool for the signature of this variable
220     */
221    public final void setSignatureIndex( final int signature_index ) { // TODO unused
222        this.signature_index = signature_index;
223    }
224
225
226    /**
227     * @param index the index in the local variable table of this variable
228     */
229    public final void setIndex( final int index ) { // TODO unused
230        this.index = index;
231    }
232
233
234    /**
235     * @param start_pc Specify range where the local variable is valid.
236     */
237    public final void setStartPC( final int start_pc ) { // TODO unused
238        this.start_pc = start_pc;
239    }
240
241
242    /**
243     * @return string representation.
244     */
245    @Override
246    public final String toString() {
247        return toStringShared(false);
248    }
249
250
251    /**
252     * @return deep copy of this object
253     */
254    public LocalVariable copy() {
255        try {
256            return (LocalVariable) clone();
257        } catch (final CloneNotSupportedException e) {
258            // TODO should this throw?
259        }
260        return null;
261    }
262}