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;
023import java.util.Arrays;
024
025import org.apache.bcel.Const;
026import org.apache.commons.lang3.ArrayUtils;
027
028/**
029 * This class is derived from <em>Attribute</em> and records the classes and interfaces that are authorized to claim
030 * membership in the nest hosted by the current class or interface. There may be at most one NestMembers attribute in a
031 * ClassFile structure.
032 *
033 * @see Attribute
034 */
035public final class NestMembers extends Attribute {
036
037    private int[] classes;
038
039    /**
040     * Construct object from input stream.
041     *
042     * @param name_index Index in constant pool
043     * @param length Content length in bytes
044     * @param input Input stream
045     * @param constant_pool Array of constants
046     * @throws IOException if an I/O error occurs.
047     */
048    NestMembers(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
049        this(name_index, length, (int[]) null, constant_pool);
050        final int number_of_classes = input.readUnsignedShort();
051        classes = new int[number_of_classes];
052        for (int i = 0; i < number_of_classes; i++) {
053            classes[i] = input.readUnsignedShort();
054        }
055    }
056
057    /**
058     * @param name_index Index in constant pool
059     * @param length Content length in bytes
060     * @param classes Table of indices in constant pool
061     * @param constant_pool Array of constants
062     */
063    public NestMembers(final int name_index, final int length, final int[] classes, final ConstantPool constant_pool) {
064        super(Const.ATTR_NEST_MEMBERS, name_index, length, constant_pool);
065        this.classes = classes != null ? classes : ArrayUtils.EMPTY_INT_ARRAY;
066    }
067
068    /**
069     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
070     * physical copy.
071     */
072    public NestMembers(final NestMembers c) {
073        this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
074    }
075
076    /**
077     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
078     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
079     *
080     * @param v Visitor object
081     */
082    @Override
083    public void accept(final Visitor v) {
084        v.visitNestMembers(this);
085    }
086
087    /**
088     * @return deep copy of this attribute
089     */
090    @Override
091    public Attribute copy(final ConstantPool constantPool) {
092        final NestMembers c = (NestMembers) clone();
093        if (classes != null) {
094            c.classes = new int[classes.length];
095            System.arraycopy(classes, 0, c.classes, 0, classes.length);
096        }
097        c.setConstantPool(constantPool);
098        return c;
099    }
100
101    /**
102     * Dump NestMembers attribute to file stream in binary format.
103     *
104     * @param file Output file stream
105     * @throws IOException if an I/O error occurs.
106     */
107    @Override
108    public void dump(final DataOutputStream file) throws IOException {
109        super.dump(file);
110        file.writeShort(classes.length);
111        for (final int index : classes) {
112            file.writeShort(index);
113        }
114    }
115
116    /**
117     * @return array of indices into constant pool of class names.
118     */
119    public int[] getClasses() {
120        return classes;
121    }
122
123    /**
124     * @return string array of class names
125     */
126    public String[] getClassNames() {
127        final String[] names = new String[classes.length];
128        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
129        return names;
130    }
131
132    /**
133     * @return Length of classes table.
134     */
135    public int getNumberClasses() {
136        return classes == null ? 0 : classes.length;
137    }
138
139    /**
140     * @param classes the list of class indexes Also redefines number_of_classes according to table length.
141     */
142    public void setClasses(final int[] classes) {
143        this.classes = classes != null ? classes : ArrayUtils.EMPTY_INT_ARRAY;
144    }
145
146    /**
147     * @return String representation, i.e., a list of classes.
148     */
149    @Override
150    public String toString() {
151        final StringBuilder buf = new StringBuilder();
152        buf.append("NestMembers(");
153        buf.append(classes.length);
154        buf.append("):\n");
155        for (final int index : classes) {
156            final String className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
157            buf.append("  ").append(Utility.compactClassName(className, false)).append("\n");
158        }
159        return buf.substring(0, buf.length() - 1); // remove the last newline
160    }
161}