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    /**
057     * Constructs a ConstantDynamic.
058     *
059     * @param bootstrapMethodAttrIndex Index to the bootstrap method.
060     * @param nameAndTypeIndex Index to the name and type.
061     */
062    public ConstantDynamic(final int bootstrapMethodAttrIndex, final int nameAndTypeIndex) {
063        super(Const.CONSTANT_Dynamic, bootstrapMethodAttrIndex, nameAndTypeIndex);
064    }
065
066    /**
067     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
068     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
069     *
070     * @param v Visitor object.
071     */
072    @Override
073    public void accept(final Visitor v) {
074        v.visitConstantDynamic(this);
075    }
076
077    /**
078     * Gets the reference (index) to bootstrap method this constant refers to.
079     *
080     * @return Reference (index) to bootstrap method this constant refers to.
081     *
082     *         Note that this method is a functional duplicate of getClassIndex for use by ConstantInvokeDynamic.
083     * @since 6.0
084     */
085    public int getBootstrapMethodAttrIndex() {
086        return super.getClassIndex(); // AKA bootstrap_method_attr_index
087    }
088
089    /**
090     * @return String representation.
091     */
092    @Override
093    public String toString() {
094        return super.toString().replace("class_index", "bootstrap_method_attr_index");
095    }
096}