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 */
017package org.apache.bcel.classfile;
018
019import java.io.DataInput;
020import java.io.IOException;
021
022import org.apache.bcel.Const;
023
024/**
025 * This class is derived from the abstract {@link Constant} and represents a reference to a dynamically computed
026 * constant.
027 *
028 * @see Constant
029 * @see <a href="https://bugs.openjdk.java.net/secure/attachment/74618/constant-dynamic.html"> Change request for JEP
030 *      309</a>
031 * @since 6.3
032 */
033public final class ConstantDynamic extends ConstantCP {
034
035    /**
036     * Initialize from another object.
037     *
038     * @param c Source to copy.
039     */
040    public ConstantDynamic(final ConstantDynamic c) {
041        this(c.getBootstrapMethodAttrIndex(), c.getNameAndTypeIndex());
042    }
043
044    /**
045     * Initialize instance from file data.
046     *
047     * @param file Input stream
048     * @throws IOException if an I/O error occurs.
049     */
050    ConstantDynamic(final DataInput file) throws IOException {
051        this(file.readShort(), file.readShort());
052    }
053
054    public ConstantDynamic(final int bootstrapMethodAttrIndex, final int nameAndTypeIndex) {
055        super(Const.CONSTANT_Dynamic, bootstrapMethodAttrIndex, nameAndTypeIndex);
056    }
057
058    /**
059     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
060     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
061     *
062     * @param v Visitor object
063     */
064    @Override
065    public void accept(final Visitor v) {
066        v.visitConstantDynamic(this);
067    }
068
069    /**
070     * @return Reference (index) to bootstrap method this constant refers to.
071     *
072     *         Note that this method is a functional duplicate of getClassIndex for use by ConstantInvokeDynamic.
073     * @since 6.0
074     */
075    public int getBootstrapMethodAttrIndex() {
076        return super.getClassIndex(); // AKA bootstrap_method_attr_index
077    }
078
079    /**
080     * @return String representation
081     */
082    @Override
083    public String toString() {
084        return super.toString().replace("class_index", "bootstrap_method_attr_index");
085    }
086}