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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   *
17   */
18  package org.apache.bcel.generic;
19  
20  import org.apache.bcel.ExceptionConst;
21  
22  /**
23   * CHECKCAST - Check whether object is of given type
24   * <PRE>Stack: ..., objectref -&gt; ..., objectref</PRE>
25   *
26   * @version $Id: CHECKCAST.html 1021978 2017-12-09 17:38:21Z ggregory $
27   */
28  public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer,
29          StackConsumer {
30  
31      /**
32       * Empty constructor needed for Instruction.readInstruction.
33       * Not to be used otherwise.
34       */
35      CHECKCAST() {
36      }
37  
38  
39      /** Check whether object is of given type
40       * @param index index to class in constant pool
41       */
42      public CHECKCAST(final int index) {
43          super(org.apache.bcel.Const.CHECKCAST, index);
44      }
45  
46  
47      /** @return exceptions this instruction may cause
48       */
49      @Override
50      public Class<?>[] getExceptions() {
51          return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_CLASS_AND_INTERFACE_RESOLUTION,
52              ExceptionConst.CLASS_CAST_EXCEPTION);
53      }
54  
55  
56      @Override
57      public ObjectType getLoadClassType( final ConstantPoolGen cpg ) {
58          Type t = getType(cpg);
59          if (t instanceof ArrayType) {
60              t = ((ArrayType) t).getBasicType();
61          }
62          return (t instanceof ObjectType) ? (ObjectType) t : null;
63      }
64  
65  
66      /**
67       * Call corresponding visitor method(s). The order is:
68       * Call visitor methods of implemented interfaces first, then
69       * call methods according to the class hierarchy in descending order,
70       * i.e., the most specific visitXXX() call comes last.
71       *
72       * @param v Visitor object
73       */
74      @Override
75      public void accept( final Visitor v ) {
76          v.visitLoadClass(this);
77          v.visitExceptionThrower(this);
78          v.visitStackProducer(this);
79          v.visitStackConsumer(this);
80          v.visitTypedInstruction(this);
81          v.visitCPInstruction(this);
82          v.visitCHECKCAST(this);
83      }
84  }