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