    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}