    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}