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 */
019package org.apache.bcel.classfile;
020
021import java.io.DataInput;
022import java.io.IOException;
023
024import org.apache.bcel.Const;
025
026/**
027 * This class is derived from the abstract {@link Constant} and represents a reference to a dynamically computed
028 * constant.
029 *
030 * @see Constant
031 * @see <a href="https://bugs.openjdk.java.net/secure/attachment/74618/constant-dynamic.html"> Change request for JEP
032 *      309</a>
033 * @since 6.3
034 */
035public final class ConstantDynamic extends ConstantCP {
036
037    /**
038     * Initialize from another object.
039     *
040     * @param c Source to copy.
041     */
042    public ConstantDynamic(final ConstantDynamic c) {
043        this(c.getBootstrapMethodAttrIndex(), c.getNameAndTypeIndex());
044    }
045
046    /**
047     * Initialize instance from file data.
048     *
049     * @param file Input stream
050     * @throws IOException if an I/O error occurs.
051     */
052    ConstantDynamic(final DataInput file) throws IOException {
053        this(file.readShort(), file.readShort());
054    }
055
056    public ConstantDynamic(final int bootstrapMethodAttrIndex, final int nameAndTypeIndex) {
057        super(Const.CONSTANT_Dynamic, bootstrapMethodAttrIndex, nameAndTypeIndex);
058    }
059
060    /**
061     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
062     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
063     *
064     * @param v Visitor object
065     */
066    @Override
067    public void accept(final Visitor v) {
068        v.visitConstantDynamic(this);
069    }
070
071    /**
072     * @return Reference (index) to bootstrap method this constant refers to.
073     *
074     *         Note that this method is a functional duplicate of getClassIndex for use by ConstantInvokeDynamic.
075     * @since 6.0
076     */
077    public int getBootstrapMethodAttrIndex() {
078        return super.getClassIndex(); // AKA bootstrap_method_attr_index
079    }
080
081    /**
082     * @return String representation
083     */
084    @Override
085    public String toString() {
086        return super.toString().replace("class_index", "bootstrap_method_attr_index");
087    }
088}