    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;
    025import org.apache.bcel.util.Args;
    026
    027/**
    028 * Extends {@link Attribute} and records the classes and
    029 * interfaces that are authorized to claim membership in the nest hosted by the
    030 * current class or interface. There may be at most one Record attribute in a
    031 * ClassFile structure.
    032 *
    033 * @see Attribute
    034 * @since 6.9.0
    035 */
    036public final class Record extends Attribute {
    037
    038    private static final RecordComponentInfo[] EMPTY_RCI_ARRAY = {};
    039
    040    private static RecordComponentInfo[] readComponents(final DataInput input, final ConstantPool constantPool)
    041            throws IOException {
    042        final int classCount = input.readUnsignedShort();
    043        final RecordComponentInfo[] components = new RecordComponentInfo[classCount];
    044        for (int i = 0; i < classCount; i++) {
    045            components[i] = new RecordComponentInfo(input, constantPool);
    046        }
    047        return components;
    048    }
    049
    050    private RecordComponentInfo[] components;
    051
    052    /**
    053     * Constructs object from input stream.
    054     *
    055     * @param nameIndex    Index in constant pool
    056     * @param length       Content length in bytes
    057     * @param input        Input stream
    058     * @param constantPool Array of constants
    059     * @throws IOException if an I/O error occurs.
    060     */
    061    Record(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool)
    062            throws IOException {
    063        this(nameIndex, length, readComponents(input, constantPool), constantPool);
    064    }
    065
    066    /**
    067     * Constructs a new instance using components.
    068     *
    069     * @param nameIndex    Index in constant pool
    070     * @param length       Content length in bytes
    071     * @param classes      Array of Record Component Info elements
    072     * @param constantPool Array of constants
    073     */
    074    public Record(final int nameIndex, final int length, final RecordComponentInfo[] classes,
    075            final ConstantPool constantPool) {
    076        super(Const.ATTR_RECORD, nameIndex, length, constantPool);
    077        this.components = classes != null ? classes : EMPTY_RCI_ARRAY;
    078        Args.requireU2(this.components.length, "attributes.length");
    079    }
    080
    081    /**
    082     * Called by objects that are traversing the nodes of the tree implicitly
    083     * defined by the contents of a Java class. For example, the hierarchy of methods,
    084     * 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.visitRecord(this);
    091    }
    092
    093    /**
    094     * Copies this instance and its components.
    095     *
    096     * @return a deep copy of this instance and its components.
    097     */
    098    @Override
    099    public Attribute copy(final ConstantPool constantPool) {
    100        final Record c = (Record) clone();
    101        if (components.length > 0) {
    102            c.components = components.clone();
    103        }
    104        c.setConstantPool(constantPool);
    105        return c;
    106    }
    107
    108    /**
    109     * Dumps this instance into a file stream in binary format.
    110     *
    111     * @param file output stream.
    112     * @throws IOException if an I/O error occurs.
    113     */
    114    @Override
    115    public void dump(final DataOutputStream file) throws IOException {
    116        super.dump(file);
    117        file.writeShort(components.length);
    118        for (final RecordComponentInfo component : components) {
    119            component.dump(file);
    120        }
    121    }
    122
    123    /**
    124     * Gets all the record components.
    125     *
    126     * @return array of Record Component Info elements.
    127     */
    128    public RecordComponentInfo[] getComponents() {
    129        return components;
    130    }
    131
    132    /**
    133     * Converts this instance to a String suitable for debugging.
    134     *
    135     * @return String a String suitable for debugging.
    136     */
    137    @Override
    138    public String toString() {
    139        final StringBuilder buf = new StringBuilder();
    140        buf.append("Record(");
    141        buf.append(components.length);
    142        buf.append("):\n");
    143        for (final RecordComponentInfo component : components) {
    144            buf.append("  ").append(component.toString()).append("\n");
    145        }
    146        return buf.substring(0, buf.length() - 1); // remove the last newline
    147    }
    148
    149}