    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.bcel.util.Args;
    027import org.apache.commons.lang3.ArrayUtils;
    028
    029/**
    030 * This class is derived from <em>Attribute</em> and records the classes and interfaces that are authorized to claim
    031 * membership in the nest hosted by the current class or interface. There may be at most one NestMembers attribute in a
    032 * ClassFile structure.
    033 *
    034 * @see Attribute
    035 */
    036public final class NestMembers extends Attribute {
    037
    038    private int[] classes;
    039
    040    /**
    041     * Constructs object from input stream.
    042     *
    043     * @param nameIndex Index in constant pool
    044     * @param length Content length in bytes
    045     * @param input Input stream
    046     * @param constantPool Array of constants
    047     * @throws IOException if an I/O error occurs.
    048     */
    049    NestMembers(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
    050        this(nameIndex, length, (int[]) null, constantPool);
    051        final int classCount = input.readUnsignedShort();
    052        classes = new int[classCount];
    053        for (int i = 0; i < classCount; i++) {
    054            classes[i] = input.readUnsignedShort();
    055        }
    056    }
    057
    058    /**
    059     * @param nameIndex Index in constant pool
    060     * @param length Content length in bytes
    061     * @param classes Table of indices in constant pool
    062     * @param constantPool Array of constants
    063     */
    064    public NestMembers(final int nameIndex, final int length, final int[] classes, final ConstantPool constantPool) {
    065        super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
    066        this.classes = ArrayUtils.nullToEmpty(classes);
    067        Args.requireU2(this.classes.length, "classes.length");
    068    }
    069
    070    /**
    071     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
    072     * physical copy.
    073     *
    074     * @param c Source to copy.
    075     */
    076    public NestMembers(final NestMembers c) {
    077        this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
    078    }
    079
    080    /**
    081     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    082     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    083     *
    084     * @param v Visitor object
    085     */
    086    @Override
    087    public void accept(final Visitor v) {
    088        v.visitNestMembers(this);
    089    }
    090
    091    /**
    092     * @return deep copy of this attribute
    093     */
    094    @Override
    095    public Attribute copy(final ConstantPool constantPool) {
    096        final NestMembers c = (NestMembers) clone();
    097        if (classes.length > 0) {
    098            c.classes = classes.clone();
    099        }
    100        c.setConstantPool(constantPool);
    101        return c;
    102    }
    103
    104    /**
    105     * Dump NestMembers attribute to file stream in binary format.
    106     *
    107     * @param file Output file stream
    108     * @throws IOException if an I/O error occurs.
    109     */
    110    @Override
    111    public void dump(final DataOutputStream file) throws IOException {
    112        super.dump(file);
    113        file.writeShort(classes.length);
    114        for (final int index : classes) {
    115            file.writeShort(index);
    116        }
    117    }
    118
    119    /**
    120     * @return array of indices into constant pool of class names.
    121     */
    122    public int[] getClasses() {
    123        return classes;
    124    }
    125
    126    /**
    127     * @return string array of class names
    128     */
    129    public String[] getClassNames() {
    130        final String[] names = new String[classes.length];
    131        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
    132        return names;
    133    }
    134
    135    /**
    136     * @return Length of classes table.
    137     */
    138    public int getNumberClasses() {
    139        return classes.length;
    140    }
    141
    142    /**
    143     * @param classes the list of class indexes Also redefines number_of_classes according to table length.
    144     */
    145    public void setClasses(final int[] classes) {
    146        this.classes = ArrayUtils.nullToEmpty(classes);
    147    }
    148
    149    /**
    150     * @return String representation, i.e., a list of classes.
    151     */
    152    @Override
    153    public String toString() {
    154        final StringBuilder buf = new StringBuilder();
    155        buf.append("NestMembers(");
    156        buf.append(classes.length);
    157        buf.append("):\n");
    158        for (final int index : classes) {
    159            final String className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
    160            buf.append("  ").append(Utility.compactClassName(className, false)).append("\n");
    161        }
    162        return buf.substring(0, buf.length() - 1); // remove the last newline
    163    }
    164}