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1   /*
2    * reserved comment block
3    * DO NOT REMOVE OR ALTER!
4    */
5   package com.sun.org.apache.bcel.internal.generic;
6   
7   /* ====================================================================
8    * The Apache Software License, Version 1.1
9    *
10   * Copyright (c) 2001 The Apache Software Foundation.  All rights
11   * reserved.
12   *
13   * Redistribution and use in source and binary forms, with or without
14   * modification, are permitted provided that the following conditions
15   * are met:
16   *
17   * 1. Redistributions of source code must retain the above copyright
18   *    notice, this list of conditions and the following disclaimer.
19   *
20   * 2. Redistributions in binary form must reproduce the above copyright
21   *    notice, this list of conditions and the following disclaimer in
22   *    the documentation and/or other materials provided with the
23   *    distribution.
24   *
25   * 3. The end-user documentation included with the redistribution,
26   *    if any, must include the following acknowledgment:
27   *       "This product includes software developed by the
28   *        Apache Software Foundation (http://www.apache.org/)."
29   *    Alternately, this acknowledgment may appear in the software itself,
30   *    if and wherever such third-party acknowledgments normally appear.
31   *
32   * 4. The names "Apache" and "Apache Software Foundation" and
33   *    "Apache BCEL" must not be used to endorse or promote products
34   *    derived from this software without prior written permission. For
35   *    written permission, please contact apache@apache.org.
36   *
37   * 5. Products derived from this software may not be called "Apache",
38   *    "Apache BCEL", nor may "Apache" appear in their name, without
39   *    prior written permission of the Apache Software Foundation.
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41   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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47   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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49   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52   * SUCH DAMAGE.
53   * ====================================================================
54   *
55   * This software consists of voluntary contributions made by many
56   * individuals on behalf of the Apache Software Foundation.  For more
57   * information on the Apache Software Foundation, please see
58   * <http://www.apache.org/>.
59   */
60  import com.sun.org.apache.bcel.internal.ExceptionConstants;
61  /**
62   * CHECKCAST - Check whether object is of given type
63   * <PRE>Stack: ..., objectref -&gt; ..., objectref</PRE>
64   *
65   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
66   */
67  public class CHECKCAST extends CPInstruction
68    implements LoadClass, ExceptionThrower, StackProducer, StackConsumer {
69    /**
70     * Empty constructor needed for the Class.newInstance() statement in
71     * Instruction.readInstruction(). Not to be used otherwise.
72     */
73    CHECKCAST() {}
74  
75    /** Check whether object is of given type
76     * @param n index to class in constant pool
77     */
78    public CHECKCAST(int index) {
79      super(com.sun.org.apache.bcel.internal.Constants.CHECKCAST, index);
80    }
81  
82    /** @return exceptions this instruction may cause
83     */
84    public Class[] getExceptions() {
85      Class[] cs = new Class[1 + ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length];
86  
87      System.arraycopy(ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION, 0,
88                       cs, 0, ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length);
89      cs[ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length] =
90        ExceptionConstants.CLASS_CAST_EXCEPTION;
91      return cs;
92    }
93  
94    public ObjectType getLoadClassType(ConstantPoolGen cpg) {
95      Type t = getType(cpg);
96  
97      if(t instanceof ArrayType)
98        t = ((ArrayType) t).getBasicType();
99  
100     return (t instanceof ObjectType)? (ObjectType) t : null;
101   }
102 
103   /**
104    * Call corresponding visitor method(s). The order is:
105    * Call visitor methods of implemented interfaces first, then
106    * call methods according to the class hierarchy in descending order,
107    * i.e., the most specific visitXXX() call comes last.
108    *
109    * @param v Visitor object
110    */
111   public void accept(Visitor v) {
112     v.visitLoadClass(this);
113     v.visitExceptionThrower(this);
114     v.visitStackProducer(this);
115     v.visitStackConsumer(this);
116     v.visitTypedInstruction(this);
117     v.visitCPInstruction(this);
118     v.visitCHECKCAST(this);
119   }
120 }