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.generic;
019
020import org.apache.bcel.ExceptionConst;
021
022/**
023 * CHECKCAST - Check whether object is of given type
024 *
025 * <PRE>
026 * Stack: ..., objectref -&gt; ..., objectref
027 * </PRE>
028 *
029 */
030public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer, StackConsumer {
031
032    /**
033     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
034     */
035    CHECKCAST() {
036    }
037
038    /**
039     * Check whether object is of given type
040     *
041     * @param index index to class in constant pool
042     */
043    public CHECKCAST(final int index) {
044        super(org.apache.bcel.Const.CHECKCAST, index);
045    }
046
047    /**
048     * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
049     * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
050     *
051     * @param v Visitor object
052     */
053    @Override
054    public void accept(final Visitor v) {
055        v.visitLoadClass(this);
056        v.visitExceptionThrower(this);
057        v.visitStackProducer(this);
058        v.visitStackConsumer(this);
059        v.visitTypedInstruction(this);
060        v.visitCPInstruction(this);
061        v.visitCHECKCAST(this);
062    }
063
064    /**
065     * @return exceptions this instruction may cause
066     */
067    @Override
068    public Class<?>[] getExceptions() {
069        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_CLASS_AND_INTERFACE_RESOLUTION, ExceptionConst.CLASS_CAST_EXCEPTION);
070    }
071
072    @Override
073    public ObjectType getLoadClassType(final ConstantPoolGen cpg) {
074        Type t = getType(cpg);
075        if (t instanceof ArrayType) {
076            t = ((ArrayType) t).getBasicType();
077        }
078        return t instanceof ObjectType ? (ObjectType) t : null;
079    }
080}