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