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 classes and interfaces that
028 * are authorized to claim membership in the nest hosted by the current class or interface.
029 * There may be at most one NestMembers attribute in a ClassFile structure.
030 *
031 * @see     Attribute
032 */
033public final class NestMembers extends Attribute {
034
035    private int[] classes;
036
037
038    /**
039     * Initialize from another object. Note that both objects use the same
040     * references (shallow copy). Use copy() for a physical copy.
041     */
042    public NestMembers(final NestMembers c) {
043        this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
044    }
045
046
047    /**
048     * @param name_index Index in constant pool
049     * @param length Content length in bytes
050     * @param classes Table of indices in constant pool
051     * @param constant_pool Array of constants
052     */
053    public NestMembers(final int name_index, final int length, final int[] classes,
054            final ConstantPool constant_pool) {
055        super(Const.ATTR_NEST_MEMBERS, name_index, length, constant_pool);
056        this.classes = classes != null ? classes : new int[0];
057    }
058
059
060    /**
061     * Construct 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    NestMembers(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
069        this(name_index, length, (int[]) null, constant_pool);
070        final int number_of_classes = input.readUnsignedShort();
071        classes = new int[number_of_classes];
072        for (int i = 0; i < number_of_classes; i++) {
073            classes[i] = input.readUnsignedShort();
074        }
075    }
076
077
078    /**
079     * Called by objects that are traversing the nodes of the tree implicitely
080     * defined by the contents of a Java class. I.e., the hierarchy of methods,
081     * fields, attributes, etc. spawns a tree of objects.
082     *
083     * @param v Visitor object
084     */
085    @Override
086    public void accept( final Visitor v ) {
087        v.visitNestMembers(this);
088    }
089
090
091    /**
092     * Dump NestMembers attribute to file stream in binary format.
093     *
094     * @param file Output file stream
095     * @throws IOException
096     */
097    @Override
098    public void dump( final DataOutputStream file ) throws IOException {
099        super.dump(file);
100        file.writeShort(classes.length);
101        for (final int index : classes) {
102            file.writeShort(index);
103        }
104    }
105
106
107    /**
108     * @return array of indices into constant pool of class names.
109     */
110    public int[] getClasses() {
111        return classes;
112    }
113
114
115    /**
116     * @return Length of classes table.
117     */
118    public int getNumberClasses() {
119        return classes == null ? 0 : classes.length;
120    }
121
122
123    /**
124     * @return string array of class names
125     */
126    public String[] getClassNames() {
127        final String[] names = new String[classes.length];
128        for (int i = 0; i < classes.length; i++) {
129            names[i] = super.getConstantPool().getConstantString(classes[i],
130                    Const.CONSTANT_Class).replace('/', '.');
131        }
132        return names;
133    }
134
135
136    /**
137     * @param classes the list of class indexes
138     * Also redefines number_of_classes according to table length.
139     */
140    public void setClasses( final int[] classes ) {
141        this.classes = classes != null ? classes : new int[0];
142    }
143
144
145    /**
146     * @return String representation, i.e., a list of classes.
147     */
148    @Override
149    public String toString() {
150        final StringBuilder buf = new StringBuilder();
151        buf.append("NestMembers(");
152        buf.append(classes.length);
153        buf.append("):\n");
154        for (final int index : classes) {
155            final String class_name = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
156            buf.append("  ").append(Utility.compactClassName(class_name, false)).append("\n");
157        }
158        return buf.substring(0, buf.length()-1); // remove the last newline
159    }
160
161
162    /**
163     * @return deep copy of this attribute
164     */
165    @Override
166    public Attribute copy( final ConstantPool _constant_pool ) {
167        final NestMembers c = (NestMembers) clone();
168        if (classes != null) {
169            c.classes = new int[classes.length];
170            System.arraycopy(classes, 0, c.classes, 0,
171                    classes.length);
172        }
173        c.setConstantPool(_constant_pool);
174        return c;
175    }
176}