    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}