001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.bcel.classfile;
020
021import java.io.DataInput;
022import java.io.DataOutputStream;
023import java.io.IOException;
024
025import org.apache.bcel.Const;
026import org.apache.bcel.util.Args;
027
028/**
029 * This class is derived from <em>Attribute</em> and represents a reference to the source file of this class. At most
030 * one SourceFile attribute should appear per classfile. The intention of this class is that it is instantiated from the
031 * <em>Attribute.readAttribute()</em> method.
032 *
033 * @see Attribute
034 */
035public final class SourceFile extends Attribute {
036
037    private int sourceFileIndex;
038
039    /**
040     * Constructs object from input stream.
041     *
042     * @param nameIndex Index in constant pool to CONSTANT_Utf8.
043     * @param length Content length in bytes.
044     * @param input Input stream.
045     * @param constantPool Array of constants.
046     * @throws IOException Thrown if an I/O error occurs.
047     */
048    SourceFile(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
049        this(nameIndex, length, input.readUnsignedShort(), constantPool);
050    }
051
052    /**
053     * Constructs a SourceFile.
054     *
055     * @param nameIndex Index in constant pool to CONSTANT_Utf8, which should represent the string "SourceFile".
056     * @param length Content length in bytes, the value should be 2.
057     * @param constantPool The constant pool that this attribute is associated with.
058     * @param sourceFileIndex Index in constant pool to CONSTANT_Utf8. This string will be interpreted as the name of the
059     *        file from which this class was compiled. It will not be interpreted as indicating the name of the directory
060     *        contqining the file or an absolute path; this information has to be supplied the consumer of this attribute -
061     *        in many cases, the JVM.
062     */
063    public SourceFile(final int nameIndex, final int length, final int sourceFileIndex, final ConstantPool constantPool) {
064        super(Const.ATTR_SOURCE_FILE, nameIndex, Args.require(length, 2, "SourceFile length attribute"), constantPool);
065        this.sourceFileIndex = Args.requireU2(sourceFileIndex, 0, constantPool.getLength(), "SourceFile source file index");
066    }
067
068    /**
069     * Initialize from another object. Note that both objects use the same references (shallow copy). Use clone() for a
070     * physical copy.
071     *
072     * @param c Source to copy.
073     */
074    public SourceFile(final SourceFile c) {
075        this(c.getNameIndex(), c.getLength(), c.getSourceFileIndex(), c.getConstantPool());
076    }
077
078    /**
079     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
080     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
081     *
082     * @param v Visitor object.
083     */
084    @Override
085    public void accept(final Visitor v) {
086        v.visitSourceFile(this);
087    }
088
089    /**
090     * @return deep copy of this attribute.
091     */
092    @Override
093    public Attribute copy(final ConstantPool constantPool) {
094        return (Attribute) clone();
095    }
096
097    /**
098     * Dumps source file attribute to file stream in binary format.
099     *
100     * @param file Output file stream.
101     * @throws IOException Thrown if an I/O error occurs.
102     */
103    @Override
104    public void dump(final DataOutputStream file) throws IOException {
105        super.dump(file);
106        file.writeShort(sourceFileIndex);
107    }
108
109    /**
110     * Gets the source file index.
111     *
112     * @return Index in constant pool of source file name.
113     */
114    public int getSourceFileIndex() {
115        return sourceFileIndex;
116    }
117
118    /**
119     * Gets the source file name.
120     *
121     * @return Source file name.
122     */
123    public String getSourceFileName() {
124        return super.getConstantPool().getConstantUtf8(sourceFileIndex).getBytes();
125    }
126
127    /**
128     * Sets the source file index.
129     *
130     * @param sourceFileIndex The source file index to set.
131     */
132    public void setSourceFileIndex(final int sourceFileIndex) {
133        this.sourceFileIndex = sourceFileIndex;
134    }
135
136    /**
137     * @return String representation.
138     */
139    @Override
140    public String toString() {
141        return "SourceFile: " + getSourceFileName();
142    }
143}