    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    public ConstantDynamic(final ConstantDynamic c) {
    039        this(c.getBootstrapMethodAttrIndex(), c.getNameAndTypeIndex());
    040    }
    041
    042    /**
    043     * Initialize instance from file data.
    044     *
    045     * @param file Input stream
    046     * @throws IOException if an I/O error occurs.
    047     */
    048    ConstantDynamic(final DataInput file) throws IOException {
    049        this(file.readShort(), file.readShort());
    050    }
    051
    052    public ConstantDynamic(final int bootstrapMethodAttrIndex, final int nameAndTypeIndex) {
    053        super(Const.CONSTANT_Dynamic, bootstrapMethodAttrIndex, nameAndTypeIndex);
    054    }
    055
    056    /**
    057     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
    058     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    059     *
    060     * @param v Visitor object
    061     */
    062    @Override
    063    public void accept(final Visitor v) {
    064        v.visitConstantDynamic(this);
    065    }
    066
    067    /**
    068     * @return Reference (index) to bootstrap method this constant refers to.
    069     *
    070     *         Note that this method is a functional duplicate of getClassIndex for use by ConstantInvokeDynamic.
    071     * @since 6.0
    072     */
    073    public int getBootstrapMethodAttrIndex() {
    074        return super.getClassIndex(); // AKA bootstrap_method_attr_index
    075    }
    076
    077    /**
    078     * @return String representation
    079     */
    080    @Override
    081    public String toString() {
    082        return super.toString().replace("class_index", "bootstrap_method_attr_index");
    083    }
    084}