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Java > Open Source Codes > com > sun > org > apache > bcel > internal > generic > CHECKCAST


1 package com.sun.org.apache.bcel.internal.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 com.sun.org.apache.bcel.internal.ExceptionConstants;
57 /**
58  * CHECKCAST - Check whether object is of given type
59  * <PRE>Stack: ..., objectref -&gt; ..., 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(com.sun.org.apache.bcel.internal.Constants.CHECKCAST, index);
77   }
78
79   /** @return exceptions this instruction may cause
80    */
81   public Class JavaDoc[] getExceptions() {
82     Class JavaDoc[] cs = new Class JavaDoc[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 }
118
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