    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 * <PRE>Stack: ..., objectref -&gt; ..., objectref</PRE>
    025 *
    026 */
    027public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer,
    028        StackConsumer {
    029
    030    /**
    031     * Empty constructor needed for Instruction.readInstruction.
    032     * Not to be used otherwise.
    033     */
    034    CHECKCAST() {
    035    }
    036
    037
    038    /** Check whether object is of given type
    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    /** @return exceptions this instruction may cause
    047     */
    048    @Override
    049    public Class<?>[] getExceptions() {
    050        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_CLASS_AND_INTERFACE_RESOLUTION,
    051            ExceptionConst.CLASS_CAST_EXCEPTION);
    052    }
    053
    054
    055    @Override
    056    public ObjectType getLoadClassType( final ConstantPoolGen cpg ) {
    057        Type t = getType(cpg);
    058        if (t instanceof ArrayType) {
    059            t = ((ArrayType) t).getBasicType();
    060        }
    061        return (t instanceof ObjectType) ? (ObjectType) t : null;
    062    }
    063
    064
    065    /**
    066     * Call corresponding visitor method(s). The order is:
    067     * Call visitor methods of implemented interfaces first, then
    068     * call methods according to the class hierarchy in descending order,
    069     * i.e., the most specific visitXXX() call comes last.
    070     *
    071     * @param v Visitor object
    072     */
    073    @Override
    074    public void accept( final Visitor v ) {
    075        v.visitLoadClass(this);
    076        v.visitExceptionThrower(this);
    077        v.visitStackProducer(this);
    078        v.visitStackConsumer(this);
    079        v.visitTypedInstruction(this);
    080        v.visitCPInstruction(this);
    081        v.visitCHECKCAST(this);
    082    }
    083}