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