    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;
    023
    024import org.apache.bcel.Const;
    025
    026/**
    027 * This class is derived from <em>Attribute</em> and records the classes and interfaces that
    028 * are authorized to claim membership in the nest hosted by the current class or interface.
    029 * There may be at most one NestMembers attribute in a ClassFile structure.
    030 *
    031 * @see     Attribute
    032 */
    033public final class NestMembers extends Attribute {
    034
    035    private int[] classes;
    036
    037
    038    /**
    039     * Initialize from another object. Note that both objects use the same
    040     * references (shallow copy). Use copy() for a physical copy.
    041     */
    042    public NestMembers(final NestMembers c) {
    043        this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
    044    }
    045
    046
    047    /**
    048     * @param name_index Index in constant pool
    049     * @param length Content length in bytes
    050     * @param classes Table of indices in constant pool
    051     * @param constant_pool Array of constants
    052     */
    053    public NestMembers(final int name_index, final int length, final int[] classes,
    054            final ConstantPool constant_pool) {
    055        super(Const.ATTR_NEST_MEMBERS, name_index, length, constant_pool);
    056        this.classes = classes != null ? classes : new int[0];
    057    }
    058
    059
    060    /**
    061     * Construct object from input stream.
    062     * @param name_index Index in constant pool
    063     * @param length Content length in bytes
    064     * @param input Input stream
    065     * @param constant_pool Array of constants
    066     * @throws IOException
    067     */
    068    NestMembers(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
    069        this(name_index, length, (int[]) null, constant_pool);
    070        final int number_of_classes = input.readUnsignedShort();
    071        classes = new int[number_of_classes];
    072        for (int i = 0; i < number_of_classes; i++) {
    073            classes[i] = input.readUnsignedShort();
    074        }
    075    }
    076
    077
    078    /**
    079     * Called by objects that are traversing the nodes of the tree implicitely
    080     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    081     * fields, attributes, etc. spawns a tree of objects.
    082     *
    083     * @param v Visitor object
    084     */
    085    @Override
    086    public void accept( final Visitor v ) {
    087        v.visitNestMembers(this);
    088    }
    089
    090
    091    /**
    092     * Dump NestMembers attribute to file stream in binary format.
    093     *
    094     * @param file Output file stream
    095     * @throws IOException
    096     */
    097    @Override
    098    public void dump( final DataOutputStream file ) throws IOException {
    099        super.dump(file);
    100        file.writeShort(classes.length);
    101        for (final int index : classes) {
    102            file.writeShort(index);
    103        }
    104    }
    105
    106
    107    /**
    108     * @return array of indices into constant pool of class names.
    109     */
    110    public int[] getClasses() {
    111        return classes;
    112    }
    113
    114
    115    /**
    116     * @return Length of classes table.
    117     */
    118    public int getNumberClasses() {
    119        return classes == null ? 0 : classes.length;
    120    }
    121
    122
    123    /**
    124     * @return string array of class names
    125     */
    126    public String[] getClassNames() {
    127        final String[] names = new String[classes.length];
    128        for (int i = 0; i < classes.length; i++) {
    129            names[i] = super.getConstantPool().getConstantString(classes[i],
    130                    Const.CONSTANT_Class).replace('/', '.');
    131        }
    132        return names;
    133    }
    134
    135
    136    /**
    137     * @param classes the list of class indexes
    138     * Also redefines number_of_classes according to table length.
    139     */
    140    public void setClasses( final int[] classes ) {
    141        this.classes = classes != null ? classes : new int[0];
    142    }
    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 class_name = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
    156            buf.append("  ").append(Utility.compactClassName(class_name, false)).append("\n");
    157        }
    158        return buf.substring(0, buf.length()-1); // remove the last newline
    159    }
    160
    161
    162    /**
    163     * @return deep copy of this attribute
    164     */
    165    @Override
    166    public Attribute copy( final ConstantPool _constant_pool ) {
    167        final NestMembers c = (NestMembers) clone();
    168        if (classes != null) {
    169            c.classes = new int[classes.length];
    170            System.arraycopy(classes, 0, c.classes, 0,
    171                    classes.length);
    172        }
    173        c.setConstantPool(_constant_pool);
    174        return c;
    175    }
    176}