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 <em>Attribute</em> and records the nest host of the nest
028 * to which the current class or interface claims to belong.
029 * There may be at most one NestHost attribute in a ClassFile structure.
030 *
031 * @see     Attribute
032 */
033public final class NestHost extends Attribute {
034
035    private int host_class_index;
036
037
038    /**
039     * Initializes from another object. Note that both objects use the same
040     * references (shallow copy). Use copy() for a physical copy.
041     */
042    public NestHost(final NestHost c) {
043        this(c.getNameIndex(), c.getLength(), c.getHostClassIndex(), c.getConstantPool());
044    }
045
046
047    /**
048     * @param name_index Index in constant pool
049     * @param length Content length in bytes
050     * @param host_class_index Host class index
051     * @param constant_pool Array of constants
052     */
053    public NestHost(final int name_index, final int length, final int host_class_index,
054            final ConstantPool constant_pool) {
055        super(Const.ATTR_NEST_MEMBERS, name_index, length, constant_pool);
056        this.host_class_index = host_class_index;
057    }
058
059
060    /**
061     * Constructs object from input stream.
062     * @param name_index Index in constant pool
063     * @param length Content length in bytes
064     * @param input Input stream
065     * @param constant_pool Array of constants
066     * @throws IOException
067     */
068    NestHost(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
069        this(name_index, length, 0, constant_pool);
070        host_class_index = input.readUnsignedShort();
071    }
072
073
074    /**
075     * Called by objects that are traversing the nodes of the tree implicitely
076     * defined by the contents of a Java class. I.e., the hierarchy of methods,
077     * fields, attributes, etc. spawns a tree of objects.
078     *
079     * @param v Visitor object
080     */
081    @Override
082    public void accept( final Visitor v ) {
083        v.visitNestHost(this);
084    }
085
086
087    /**
088     * Dumps NestHost attribute to file stream in binary format.
089     *
090     * @param file Output file stream
091     * @throws IOException if an I/O error occurs.
092     */
093    @Override
094    public void dump( final DataOutputStream file ) throws IOException {
095        super.dump(file);
096        file.writeShort(host_class_index);
097    }
098
099
100    /**
101     * @return index into constant pool of host class name.
102     */
103    public int getHostClassIndex() {
104        return host_class_index;
105    }
106
107
108    /**
109     * @param host_class_index the host class index
110     */
111    public void setHostClassIndex( final int host_class_index ) {
112        this.host_class_index = host_class_index;
113    }
114
115
116    /**
117     * @return String representation
118     */
119    @Override
120    public String toString() {
121        final StringBuilder buf = new StringBuilder();
122        buf.append("NestHost: ");
123        final String class_name = super.getConstantPool().getConstantString(host_class_index, Const.CONSTANT_Class);
124        buf.append(Utility.compactClassName(class_name, false));
125        return buf.toString();
126    }
127
128
129    /**
130     * @return deep copy of this attribute
131     */
132    @Override
133    public Attribute copy( final ConstantPool _constant_pool ) {
134        final NestHost c = (NestHost) clone();
135        c.setConstantPool(_constant_pool);
136        return c;
137    }
138}