    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 * @version $Id$
    027 */
    028public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer,
    029        StackConsumer {
    030
    031    /**
    032     * Empty constructor needed for Instruction.readInstruction.
    033     * Not to be used otherwise.
    034     */
    035    CHECKCAST() {
    036    }
    037
    038
    039    /** Check whether object is of given type
    040     * @param index index to class in constant pool
    041     */
    042    public CHECKCAST(final int index) {
    043        super(org.apache.bcel.Const.CHECKCAST, index);
    044    }
    045
    046
    047    /** @return exceptions this instruction may cause
    048     */
    049    @Override
    050    public Class<?>[] getExceptions() {
    051        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_CLASS_AND_INTERFACE_RESOLUTION,
    052            ExceptionConst.CLASS_CAST_EXCEPTION);
    053    }
    054
    055
    056    @Override
    057    public ObjectType getLoadClassType( final ConstantPoolGen cpg ) {
    058        Type t = getType(cpg);
    059        if (t instanceof ArrayType) {
    060            t = ((ArrayType) t).getBasicType();
    061        }
    062        return (t instanceof ObjectType) ? (ObjectType) t : null;
    063    }
    064
    065
    066    /**
    067     * Call corresponding visitor method(s). The order is:
    068     * Call visitor methods of implemented interfaces first, then
    069     * call methods according to the class hierarchy in descending order,
    070     * i.e., the most specific visitXXX() call comes last.
    071     *
    072     * @param v Visitor object
    073     */
    074    @Override
    075    public void accept( final Visitor v ) {
    076        v.visitLoadClass(this);
    077        v.visitExceptionThrower(this);
    078        v.visitStackProducer(this);
    079        v.visitStackConsumer(this);
    080        v.visitTypedInstruction(this);
    081        v.visitCPInstruction(this);
    082        v.visitCHECKCAST(this);
    083    }
    084}