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 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    NestMembers(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
049        this(nameIndex, length, (int[]) null, constantPool);
050        final int classCount = input.readUnsignedShort();
051        classes = new int[classCount];
052        for (int i = 0; i < classCount; i++) {
053            classes[i] = input.readUnsignedShort();
054        }
055    }
056
057    /**
058     * @param nameIndex Index in constant pool
059     * @param length Content length in bytes
060     * @param classes Table of indices in constant pool
061     * @param constantPool Array of constants
062     */
063    public NestMembers(final int nameIndex, final int length, final int[] classes, final ConstantPool constantPool) {
064        super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
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 = classes.clone();
095        }
096        c.setConstantPool(constantPool);
097        return c;
098    }
099
100    /**
101     * Dump NestMembers attribute to file stream in binary format.
102     *
103     * @param file Output file stream
104     * @throws IOException if an I/O error occurs.
105     */
106    @Override
107    public void dump(final DataOutputStream file) throws IOException {
108        super.dump(file);
109        file.writeShort(classes.length);
110        for (final int index : classes) {
111            file.writeShort(index);
112        }
113    }
114
115    /**
116     * @return array of indices into constant pool of class names.
117     */
118    public int[] getClasses() {
119        return classes;
120    }
121
122    /**
123     * @return string array of class names
124     */
125    public String[] getClassNames() {
126        final String[] names = new String[classes.length];
127        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
128        return names;
129    }
130
131    /**
132     * @return Length of classes table.
133     */
134    public int getNumberClasses() {
135        return classes == null ? 0 : classes.length;
136    }
137
138    /**
139     * @param classes the list of class indexes Also redefines number_of_classes according to table length.
140     */
141    public void setClasses(final int[] classes) {
142        this.classes = classes != null ? classes : ArrayUtils.EMPTY_INT_ARRAY;
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 className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
156            buf.append("  ").append(Utility.compactClassName(className, false)).append("\n");
157        }
158        return buf.substring(0, buf.length() - 1); // remove the last newline
159    }
160}