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.generic;
018
019import org.apache.bcel.ExceptionConst;
020
021/**
022 * CHECKCAST - Check whether object is of given type
023 *
024 * <PRE>
025 * Stack: ..., objectref -&gt; ..., objectref
026 * </PRE>
027 */
028public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer, StackConsumer {
029
030    /**
031     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
032     */
033    CHECKCAST() {
034    }
035
036    /**
037     * Check whether object is of given type
038     *
039     * @param index index to class in constant pool
040     */
041    public CHECKCAST(final int index) {
042        super(org.apache.bcel.Const.CHECKCAST, index);
043    }
044
045    /**
046     * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
047     * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
048     *
049     * @param v Visitor object
050     */
051    @Override
052    public void accept(final Visitor v) {
053        v.visitLoadClass(this);
054        v.visitExceptionThrower(this);
055        v.visitStackProducer(this);
056        v.visitStackConsumer(this);
057        v.visitTypedInstruction(this);
058        v.visitCPInstruction(this);
059        v.visitCHECKCAST(this);
060    }
061
062    /**
063     * @return exceptions this instruction may cause
064     */
065    @Override
066    public Class<?>[] getExceptions() {
067        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_CLASS_AND_INTERFACE_RESOLUTION, ExceptionConst.CLASS_CAST_EXCEPTION);
068    }
069
070    @Override
071    public ObjectType getLoadClassType(final ConstantPoolGen cpg) {
072        Type t = getType(cpg);
073        if (t instanceof ArrayType) {
074            t = ((ArrayType) t).getBasicType();
075        }
076        return t instanceof ObjectType ? (ObjectType) t : null;
077    }
078}