1   package org.apache.bcel.generic;
2   
3   /* ====================================================================
4    * The Apache Software License, Version 1.1
5    *
6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
7    * reserved.
8    *
9    * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   *
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer.
15   *
16   * 2. Redistributions in binary form must reproduce the above copyright
17   *    notice, this list of conditions and the following disclaimer in
18   *    the documentation and/or other materials provided with the
19   *    distribution.
20   *
21   * 3. The end-user documentation included with the redistribution,
22   *    if any, must include the following acknowledgment:
23   *       "This product includes software developed by the
24   *        Apache Software Foundation (http://www.apache.org/)."
25   *    Alternately, this acknowledgment may appear in the software itself,
26   *    if and wherever such third-party acknowledgments normally appear.
27   *
28   * 4. The names "Apache" and "Apache Software Foundation" and
29   *    "Apache BCEL" must not be used to endorse or promote products
30   *    derived from this software without prior written permission. For
31   *    written permission, please contact apache@apache.org.
32   *
33   * 5. Products derived from this software may not be called "Apache",
34   *    "Apache BCEL", nor may "Apache" appear in their name, without
35   *    prior written permission of the Apache Software Foundation.
36   *
37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48   * SUCH DAMAGE.
49   * ====================================================================
50   *
51   * This software consists of voluntary contributions made by many
52   * individuals on behalf of the Apache Software Foundation.  For more
53   * information on the Apache Software Foundation, please see
54   * <http://www.apache.org/>.
55   */
56  import org.apache.bcel.ExceptionConstants;
57  /*** 
58   * CHECKCAST - Check whether object is of given type
59   * <PRE>Stack: ..., objectref -> ..., objectref</PRE>
60   *
61   * @version $Id: CHECKCAST.java,v 1.1.1.1 2001/10/29 20:00:07 jvanzyl Exp $
62   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
63   */
64  public class CHECKCAST extends CPInstruction
65    implements LoadClass, ExceptionThrower, StackProducer, StackConsumer {
66    /***
67     * Empty constructor needed for the Class.newInstance() statement in
68     * Instruction.readInstruction(). Not to be used otherwise.
69     */
70    CHECKCAST() {}
71  
72    /*** Check whether object is of given type
73     * @param n index to class in constant pool
74     */
75    public CHECKCAST(int index) {
76      super(org.apache.bcel.Constants.CHECKCAST, index);
77    }
78  
79    /*** @return exceptions this instruction may cause
80     */
81    public Class[] getExceptions() {
82      Class[] cs = new Class[1 + ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length];
83  
84      System.arraycopy(ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION, 0,
85  		     cs, 0, ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length);
86      cs[ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length] =
87        ExceptionConstants.CLASS_CAST_EXCEPTION;
88      return cs;
89    }
90  
91    public ObjectType getLoadClassType(ConstantPoolGen cpg) {
92      Type t = getType(cpg);
93  
94      if(t instanceof ArrayType)
95        t = ((ArrayType) t).getBasicType();
96  
97      return (t instanceof ObjectType)? (ObjectType) t : null;
98    }
99  
100   /***
101    * Call corresponding visitor method(s). The order is:
102    * Call visitor methods of implemented interfaces first, then
103    * call methods according to the class hierarchy in descending order,
104    * i.e., the most specific visitXXX() call comes last.
105    *
106    * @param v Visitor object
107    */
108   public void accept(Visitor v) {
109     v.visitLoadClass(this);
110     v.visitExceptionThrower(this);
111     v.visitStackProducer(this);
112     v.visitStackConsumer(this);
113     v.visitTypedInstruction(this);
114     v.visitCPInstruction(this);
115     v.visitCHECKCAST(this);
116   }
117 }
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