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 dataInput 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 dataInput, final ConstantPool constantPool) throws IOException {
052        this(nameIndex, length, (int[]) null, constantPool);
053        classes = ClassParser.readU2U2Table(dataInput);
054    }
055
056    /**
057     * @param nameIndex Index in constant pool.
058     * @param length Content length in bytes.
059     * @param classes Table of indices in constant pool.
060     * @param constantPool Array of constants.
061     */
062    public NestMembers(final int nameIndex, final int length, final int[] classes, final ConstantPool constantPool) {
063        super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
064        this.classes = ArrayUtils.nullToEmpty(classes);
065        Args.requireU2(this.classes.length, "classes.length");
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     * @param c Source to copy.
073     */
074    public NestMembers(final NestMembers c) {
075        this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
076    }
077
078    /**
079     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
080     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
081     *
082     * @param v Visitor object.
083     */
084    @Override
085    public void accept(final Visitor v) {
086        v.visitNestMembers(this);
087    }
088
089    /**
090     * @return deep copy of this attribute.
091     */
092    @Override
093    public Attribute copy(final ConstantPool constantPool) {
094        final NestMembers c = (NestMembers) clone();
095        if (classes.length > 0) {
096            c.classes = classes.clone();
097        }
098        c.setConstantPool(constantPool);
099        return c;
100    }
101
102    /**
103     * Dumps NestMembers attribute to file stream in binary format.
104     *
105     * @param file Output file stream.
106     * @throws IOException if an I/O error occurs.
107     */
108    @Override
109    public void dump(final DataOutputStream file) throws IOException {
110        super.dump(file);
111        file.writeShort(classes.length);
112        for (final int index : classes) {
113            file.writeShort(index);
114        }
115    }
116
117    /**
118     * @return array of indices into constant pool of class names.
119     */
120    public int[] getClasses() {
121        return classes;
122    }
123
124    /**
125     * @return string array of class names.
126     */
127    public String[] getClassNames() {
128        final String[] names = new String[classes.length];
129        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
130        return names;
131    }
132
133    /**
134     * @return Length of classes table.
135     */
136    public int getNumberClasses() {
137        return classes.length;
138    }
139
140    /**
141     * @param classes the list of class indexes Also redefines number_of_classes according to table length.
142     */
143    public void setClasses(final int[] classes) {
144        this.classes = ArrayUtils.nullToEmpty(classes);
145    }
146
147    /**
148     * @return String representation, that is, a list of classes.
149     */
150    @Override
151    public String toString() {
152        final StringBuilder buf = new StringBuilder();
153        buf.append("NestMembers(");
154        buf.append(classes.length);
155        buf.append("):\n");
156        for (final int index : classes) {
157            final String className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
158            buf.append("  ").append(Utility.compactClassName(className, false)).append("\n");
159        }
160        return buf.substring(0, buf.length() - 1); // remove the last newline
161    }
162}