    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 */
    019
    020package org.apache.bcel.classfile;
    021
    022import java.io.DataInput;
    023import java.io.DataOutputStream;
    024import java.io.IOException;
    025
    026import org.apache.bcel.Const;
    027import org.apache.bcel.util.Args;
    028
    029/**
    030 * This class is derived from <em>Attribute</em> and records the nest host of the nest to which the current class or
    031 * interface claims to belong. There may be at most one NestHost attribute in a ClassFile structure.
    032 *
    033 * @see Attribute
    034 */
    035public final class NestHost extends Attribute {
    036
    037    private int hostClassIndex;
    038
    039    /**
    040     * Constructs object from input stream.
    041     *
    042     * @param nameIndex Index in constant pool.
    043     * @param length Content length in bytes.
    044     * @param input Input stream.
    045     * @param constantPool Array of constants.
    046     * @throws IOException if an I/O error occurs.
    047     */
    048    NestHost(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
    049        this(nameIndex, length, 0, constantPool);
    050        hostClassIndex = input.readUnsignedShort();
    051    }
    052
    053    /**
    054     * @param nameIndex Index in constant pool.
    055     * @param length Content length in bytes.
    056     * @param hostClassIndex Host class index.
    057     * @param constantPool Array of constants.
    058     */
    059    public NestHost(final int nameIndex, final int length, final int hostClassIndex, final ConstantPool constantPool) {
    060        super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
    061        this.hostClassIndex = Args.requireU2(hostClassIndex, "hostClassIndex");
    062    }
    063
    064    /**
    065     * Initializes from another object. Note that both objects use the same references (shallow copy). Use copy() for a
    066     * physical copy.
    067     *
    068     * @param c Source to copy.
    069     */
    070    public NestHost(final NestHost c) {
    071        this(c.getNameIndex(), c.getLength(), c.getHostClassIndex(), c.getConstantPool());
    072    }
    073
    074    /**
    075     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    076     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    077     *
    078     * @param v Visitor object.
    079     */
    080    @Override
    081    public void accept(final Visitor v) {
    082        v.visitNestHost(this);
    083    }
    084
    085    /**
    086     * @return deep copy of this attribute.
    087     */
    088    @Override
    089    public Attribute copy(final ConstantPool constantPool) {
    090        final NestHost c = (NestHost) clone();
    091        c.setConstantPool(constantPool);
    092        return c;
    093    }
    094
    095    /**
    096     * Dumps NestHost attribute to file stream in binary format.
    097     *
    098     * @param file Output file stream.
    099     * @throws IOException if an I/O error occurs.
    100     */
    101    @Override
    102    public void dump(final DataOutputStream file) throws IOException {
    103        super.dump(file);
    104        file.writeShort(hostClassIndex);
    105    }
    106
    107    /**
    108     * @return index into constant pool of host class name.
    109     */
    110    public int getHostClassIndex() {
    111        return hostClassIndex;
    112    }
    113
    114    /**
    115     * @param hostClassIndex the host class index.
    116     */
    117    public void setHostClassIndex(final int hostClassIndex) {
    118        this.hostClassIndex = hostClassIndex;
    119    }
    120
    121    /**
    122     * @return String representation.
    123     */
    124    @Override
    125    public String toString() {
    126        final StringBuilder buf = new StringBuilder();
    127        buf.append("NestHost: ");
    128        final String className = super.getConstantPool().getConstantString(hostClassIndex, Const.CONSTANT_Class);
    129        buf.append(Utility.compactClassName(className, false));
    130        return buf.toString();
    131    }
    132}