    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 package.
    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 ConstantPackage extends Constant implements ConstantObject {
    036
    037    private int nameIndex;
    038
    039    /**
    040     * Initialize from another object.
    041     */
    042    public ConstantPackage(final ConstantPackage 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    ConstantPackage(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 ConstantPackage(final int nameIndex) {
    060        super(Const.CONSTANT_Package);
    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.visitConstantPackage(this);
    073    }
    074
    075    /**
    076     * Dump constant package 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 package 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 Package
    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}