commons-bcel-master/src/main/java/org/apache/bcel/classfile/SourceFile.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.bcel.classfile;

import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.bcel.Const;
import org.apache.bcel.util.Args;

/**
 * This class is derived from <em>Attribute</em> and represents a reference to the source file of this class. At most
 * one SourceFile attribute should appear per classfile. The intention of this class is that it is instantiated from the
 * <em>Attribute.readAttribute()</em> method.
 *
 * @see Attribute
 */
public final class SourceFile extends Attribute {

    private int sourceFileIndex;

    /**
     * Construct object from input stream.
     *
     * @param nameIndex Index in constant pool to CONSTANT_Utf8
     * @param length Content length in bytes
     * @param input Input stream
     * @param constantPool Array of constants
     * @throws IOException if an I/O error occurs.
     */
    SourceFile(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
        this(nameIndex, length, input.readUnsignedShort(), constantPool);
    }

    /**
     * @param nameIndex Index in constant pool to CONSTANT_Utf8, which should represent the string "SourceFile".
     * @param length Content length in bytes, the value should be 2.
     * @param constantPool The constant pool that this attribute is associated with.
     * @param sourceFileIndex Index in constant pool to CONSTANT_Utf8. This string will be interpreted as the name of the
     *        file from which this class was compiled. It will not be interpreted as indicating the name of the directory
     *        contqining the file or an absolute path; this information has to be supplied the consumer of this attribute -
     *        in many cases, the JVM.
     */
    public SourceFile(final int nameIndex, final int length, final int sourceFileIndex, final ConstantPool constantPool) {
        super(Const.ATTR_SOURCE_FILE, nameIndex, Args.require(length, 2, "SourceFile length attribute"), constantPool);
        this.sourceFileIndex = Args.requireU2(sourceFileIndex, 0, constantPool.getLength(), "SourceFile source file index");
    }

    /**
     * Initialize from another object. Note that both objects use the same references (shallow copy). Use clone() for a
     * physical copy.
     *
     * @param c Source to copy.
     */
    public SourceFile(final SourceFile c) {
        this(c.getNameIndex(), c.getLength(), c.getSourceFileIndex(), c.getConstantPool());
    }

    /**
     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
     *
     * @param v Visitor object
     */
    @Override
    public void accept(final Visitor v) {
        v.visitSourceFile(this);
    }

    /**
     * @return deep copy of this attribute
     */
    @Override
    public Attribute copy(final ConstantPool constantPool) {
        return (Attribute) clone();
    }

    /**
     * Dump source file attribute to file stream in binary format.
     *
     * @param file Output file stream
     * @throws IOException if an I/O error occurs.
     */
    @Override
    public void dump(final DataOutputStream file) throws IOException {
        super.dump(file);
        file.writeShort(sourceFileIndex);
    }

    /**
     * @return Index in constant pool of source file name.
     */
    public int getSourceFileIndex() {
        return sourceFileIndex;
    }

    /**
     * @return Source file name.
     */
    public String getSourceFileName() {
        return super.getConstantPool().getConstantUtf8(sourceFileIndex).getBytes();
    }

    /**
     * @param sourceFileIndex
     */
    public void setSourceFileIndex(final int sourceFileIndex) {
        this.sourceFileIndex = sourceFileIndex;
    }

    /**
     * @return String representation
     */
    @Override
    public String toString() {
        return "SourceFile: " + getSourceFileName();
    }
}
