    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.bcel.generic;
    020
    021import org.apache.bcel.ExceptionConst;
    022
    023/**
    024 * CHECKCAST - Check whether object is of given type
    025 *
    026 * <PRE>
    027 * Stack: ..., objectref -&gt; ..., objectref
    028 * </PRE>
    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}