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;
022
023import org.apache.bcel.Const;
024import org.apache.bcel.util.Args;
025
026/**
027 * This class is derived from <em>Attribute</em> and represents a reference to the source file of this class. At most
028 * one SourceFile attribute should appear per classfile. The intention of this class is that it is instantiated from the
029 * <em>Attribute.readAttribute()</em> method.
030 *
031 * @see Attribute
032 */
033public final class SourceFile extends Attribute {
034
035    private int sourceFileIndex;
036
037    /**
038     * Constructs object from input stream.
039     *
040     * @param nameIndex Index in constant pool to CONSTANT_Utf8
041     * @param length Content length in bytes
042     * @param input Input stream
043     * @param constantPool Array of constants
044     * @throws IOException if an I/O error occurs.
045     */
046    SourceFile(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
047        this(nameIndex, length, input.readUnsignedShort(), constantPool);
048    }
049
050    /**
051     * @param nameIndex Index in constant pool to CONSTANT_Utf8, which should represent the string "SourceFile".
052     * @param length Content length in bytes, the value should be 2.
053     * @param constantPool The constant pool that this attribute is associated with.
054     * @param sourceFileIndex Index in constant pool to CONSTANT_Utf8. This string will be interpreted as the name of the
055     *        file from which this class was compiled. It will not be interpreted as indicating the name of the directory
056     *        contqining the file or an absolute path; this information has to be supplied the consumer of this attribute -
057     *        in many cases, the JVM.
058     */
059    public SourceFile(final int nameIndex, final int length, final int sourceFileIndex, final ConstantPool constantPool) {
060        super(Const.ATTR_SOURCE_FILE, nameIndex, Args.require(length, 2, "SourceFile length attribute"), constantPool);
061        this.sourceFileIndex = Args.requireU2(sourceFileIndex, 0, constantPool.getLength(), "SourceFile source file index");
062    }
063
064    /**
065     * Initialize from another object. Note that both objects use the same references (shallow copy). Use clone() for a
066     * physical copy.
067     *
068     * @param c Source to copy.
069     */
070    public SourceFile(final SourceFile c) {
071        this(c.getNameIndex(), c.getLength(), c.getSourceFileIndex(), c.getConstantPool());
072    }
073
074    /**
075     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
076     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
077     *
078     * @param v Visitor object
079     */
080    @Override
081    public void accept(final Visitor v) {
082        v.visitSourceFile(this);
083    }
084
085    /**
086     * @return deep copy of this attribute
087     */
088    @Override
089    public Attribute copy(final ConstantPool constantPool) {
090        return (Attribute) clone();
091    }
092
093    /**
094     * Dump source file attribute to file stream in binary format.
095     *
096     * @param file Output file stream
097     * @throws IOException if an I/O error occurs.
098     */
099    @Override
100    public void dump(final DataOutputStream file) throws IOException {
101        super.dump(file);
102        file.writeShort(sourceFileIndex);
103    }
104
105    /**
106     * @return Index in constant pool of source file name.
107     */
108    public int getSourceFileIndex() {
109        return sourceFileIndex;
110    }
111
112    /**
113     * @return Source file name.
114     */
115    public String getSourceFileName() {
116        return super.getConstantPool().getConstantUtf8(sourceFileIndex).getBytes();
117    }
118
119    /**
120     * @param sourceFileIndex
121     */
122    public void setSourceFileIndex(final int sourceFileIndex) {
123        this.sourceFileIndex = sourceFileIndex;
124    }
125
126    /**
127     * @return String representation
128     */
129    @Override
130    public String toString() {
131        return "SourceFile: " + getSourceFileName();
132    }
133}