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}
027 * and represents a reference to a dynamically computed constant.
028 *
029 * @see     Constant
030 * @see  <a href="https://bugs.openjdk.java.net/secure/attachment/74618/constant-dynamic.html">
031 * Change request for JEP 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    /**
045     * Initialize instance from file data.
046     *
047     * @param file Input stream
048     * @throws IOException
049     */
050    ConstantDynamic(final DataInput file) throws IOException {
051        this(file.readShort(), file.readShort());
052    }
053
054
055    public ConstantDynamic(final int bootstrap_method_attr_index, final int name_and_type_index) {
056        super(Const.CONSTANT_Dynamic, bootstrap_method_attr_index, name_and_type_index);
057    }
058
059
060    /**
061     * Called by objects that are traversing the nodes of the tree implicitly
062     * defined by the contents of a Java class. I.e., the hierarchy of methods,
063     * fields, attributes, etc. spawns a tree of objects.
064     *
065     * @param v Visitor object
066     */
067    @Override
068    public void accept( final Visitor v ) {
069        v.visitConstantDynamic(this);
070    }
071
072    /**
073     * @return Reference (index) to bootstrap method this constant refers to.
074     *
075     * Note that this method is a functional duplicate of getClassIndex
076     * for use by ConstantInvokeDynamic.
077     * @since 6.0
078     */
079    public int getBootstrapMethodAttrIndex() {
080        return super.getClassIndex();  // AKA bootstrap_method_attr_index
081    }
082
083    /**
084     * @return String representation
085     */
086    @Override
087    public String toString() {
088        return super.toString().replace("class_index", "bootstrap_method_attr_index");
089    }
090}