001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019
020package org.apache.bcel.classfile;
021
022import java.io.DataInput;
023import java.io.DataOutputStream;
024import java.io.IOException;
025import java.util.Arrays;
026
027import org.apache.bcel.Const;
028import org.apache.bcel.util.Args;
029import org.apache.commons.lang3.ArrayUtils;
030
031/**
032 * This class is derived from <em>Attribute</em> and records the classes and interfaces that are authorized to claim
033 * membership in the nest hosted by the current class or interface. There may be at most one NestMembers attribute in a
034 * ClassFile structure.
035 *
036 * @see Attribute
037 */
038public final class NestMembers extends Attribute {
039
040    private int[] classes;
041
042    /**
043     * Constructs object from input stream.
044     *
045     * @param nameIndex Index in constant pool
046     * @param length Content length in bytes
047     * @param input Input stream
048     * @param constantPool Array of constants
049     * @throws IOException if an I/O error occurs.
050     */
051    NestMembers(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
052        this(nameIndex, length, (int[]) null, constantPool);
053        final int classCount = input.readUnsignedShort();
054        classes = new int[classCount];
055        for (int i = 0; i < classCount; i++) {
056            classes[i] = input.readUnsignedShort();
057        }
058    }
059
060    /**
061     * @param nameIndex Index in constant pool
062     * @param length Content length in bytes
063     * @param classes Table of indices in constant pool
064     * @param constantPool Array of constants
065     */
066    public NestMembers(final int nameIndex, final int length, final int[] classes, final ConstantPool constantPool) {
067        super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
068        this.classes = ArrayUtils.nullToEmpty(classes);
069        Args.requireU2(this.classes.length, "classes.length");
070    }
071
072    /**
073     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
074     * physical copy.
075     *
076     * @param c Source to copy.
077     */
078    public NestMembers(final NestMembers c) {
079        this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
080    }
081
082    /**
083     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
084     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
085     *
086     * @param v Visitor object
087     */
088    @Override
089    public void accept(final Visitor v) {
090        v.visitNestMembers(this);
091    }
092
093    /**
094     * @return deep copy of this attribute
095     */
096    @Override
097    public Attribute copy(final ConstantPool constantPool) {
098        final NestMembers c = (NestMembers) clone();
099        if (classes.length > 0) {
100            c.classes = classes.clone();
101        }
102        c.setConstantPool(constantPool);
103        return c;
104    }
105
106    /**
107     * Dump NestMembers attribute to file stream in binary format.
108     *
109     * @param file Output file stream
110     * @throws IOException if an I/O error occurs.
111     */
112    @Override
113    public void dump(final DataOutputStream file) throws IOException {
114        super.dump(file);
115        file.writeShort(classes.length);
116        for (final int index : classes) {
117            file.writeShort(index);
118        }
119    }
120
121    /**
122     * @return array of indices into constant pool of class names.
123     */
124    public int[] getClasses() {
125        return classes;
126    }
127
128    /**
129     * @return string array of class names
130     */
131    public String[] getClassNames() {
132        final String[] names = new String[classes.length];
133        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
134        return names;
135    }
136
137    /**
138     * @return Length of classes table.
139     */
140    public int getNumberClasses() {
141        return classes.length;
142    }
143
144    /**
145     * @param classes the list of class indexes Also redefines number_of_classes according to table length.
146     */
147    public void setClasses(final int[] classes) {
148        this.classes = ArrayUtils.nullToEmpty(classes);
149    }
150
151    /**
152     * @return String representation, i.e., a list of classes.
153     */
154    @Override
155    public String toString() {
156        final StringBuilder buf = new StringBuilder();
157        buf.append("NestMembers(");
158        buf.append(classes.length);
159        buf.append("):\n");
160        for (final int index : classes) {
161            final String className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
162            buf.append("  ").append(Utility.compactClassName(className, false)).append("\n");
163        }
164        return buf.substring(0, buf.length() - 1); // remove the last newline
165    }
166}