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;
024
025/**
026 * This class is derived from the abstract {@link Constant} and represents a reference to a module.
027 *
028 * <p>
029 * Note: Early access Java 9 support- currently subject to change
030 * </p>
031 *
032 * @see Constant
033 * @since 6.1
034 */
035public final class ConstantModule extends Constant implements ConstantObject {
036
037    private int nameIndex;
038
039    /**
040     * Initialize from another object.
041     */
042    public ConstantModule(final ConstantModule c) {
043        this(c.getNameIndex());
044    }
045
046    /**
047     * Initialize instance from file data.
048     *
049     * @param file Input stream
050     * @throws IOException if an I/O error occurs.
051     */
052    ConstantModule(final DataInput file) throws IOException {
053        this(file.readUnsignedShort());
054    }
055
056    /**
057     * @param nameIndex Name index in constant pool. Should refer to a ConstantUtf8.
058     */
059    public ConstantModule(final int nameIndex) {
060        super(Const.CONSTANT_Module);
061        this.nameIndex = nameIndex;
062    }
063
064    /**
065     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
066     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
067     *
068     * @param v Visitor object
069     */
070    @Override
071    public void accept(final Visitor v) {
072        v.visitConstantModule(this);
073    }
074
075    /**
076     * Dump constant module to file stream in binary format.
077     *
078     * @param file Output file stream
079     * @throws IOException if an I/O error occurs.
080     */
081    @Override
082    public void dump(final DataOutputStream file) throws IOException {
083        file.writeByte(super.getTag());
084        file.writeShort(nameIndex);
085    }
086
087    /**
088     * @return dereferenced string
089     */
090    public String getBytes(final ConstantPool cp) {
091        return (String) getConstantValue(cp);
092    }
093
094    /**
095     * @return String object
096     */
097    @Override
098    public Object getConstantValue(final ConstantPool cp) {
099        return cp.getConstantUtf8(nameIndex).getBytes();
100    }
101
102    /**
103     * @return Name index in constant pool of module name.
104     */
105    public int getNameIndex() {
106        return nameIndex;
107    }
108
109    /**
110     * @param nameIndex the name index in the constant pool of this Constant Module
111     */
112    public void setNameIndex(final int nameIndex) {
113        this.nameIndex = nameIndex;
114    }
115
116    /**
117     * @return String representation.
118     */
119    @Override
120    public String toString() {
121        return super.toString() + "(nameIndex = " + nameIndex + ")";
122    }
123}