    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;
    025
    026/**
    027 * This class is derived from the abstract {@link Constant} and represents a reference to a module.
    028 *
    029 * <p>
    030 * Note: Early access Java 9 support- currently subject to change
    031 * </p>
    032 *
    033 * @see Constant
    034 * @since 6.1
    035 */
    036public final class ConstantModule extends Constant implements ConstantObject {
    037
    038    private int nameIndex;
    039
    040    /**
    041     * Initialize from another object.
    042     */
    043    public ConstantModule(final ConstantModule c) {
    044        this(c.getNameIndex());
    045    }
    046
    047    /**
    048     * Initialize instance from file data.
    049     *
    050     * @param file Input stream
    051     * @throws IOException if an I/O error occurs.
    052     */
    053    ConstantModule(final DataInput file) throws IOException {
    054        this(file.readUnsignedShort());
    055    }
    056
    057    /**
    058     * @param nameIndex Name index in constant pool. Should refer to a ConstantUtf8.
    059     */
    060    public ConstantModule(final int nameIndex) {
    061        super(Const.CONSTANT_Module);
    062        this.nameIndex = nameIndex;
    063    }
    064
    065    /**
    066     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
    067     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    068     *
    069     * @param v Visitor object
    070     */
    071    @Override
    072    public void accept(final Visitor v) {
    073        v.visitConstantModule(this);
    074    }
    075
    076    /**
    077     * Dump constant module to file stream in binary format.
    078     *
    079     * @param file Output file stream
    080     * @throws IOException if an I/O error occurs.
    081     */
    082    @Override
    083    public void dump(final DataOutputStream file) throws IOException {
    084        file.writeByte(super.getTag());
    085        file.writeShort(nameIndex);
    086    }
    087
    088    /**
    089     * @return dereferenced string
    090     */
    091    public String getBytes(final ConstantPool cp) {
    092        return (String) getConstantValue(cp);
    093    }
    094
    095    /**
    096     * @return String object
    097     */
    098    @Override
    099    public Object getConstantValue(final ConstantPool cp) {
    100        return cp.getConstantUtf8(nameIndex).getBytes();
    101    }
    102
    103    /**
    104     * @return Name index in constant pool of module name.
    105     */
    106    public int getNameIndex() {
    107        return nameIndex;
    108    }
    109
    110    /**
    111     * @param nameIndex the name index in the constant pool of this Constant Module
    112     */
    113    public void setNameIndex(final int nameIndex) {
    114        this.nameIndex = nameIndex;
    115    }
    116
    117    /**
    118     * @return String representation.
    119     */
    120    @Override
    121    public String toString() {
    122        return super.toString() + "(nameIndex = " + nameIndex + ")";
    123    }
    124}