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Java > Open Source Codes > org > apache > bcel > generic > CHECKCAST


1 /*
2  * Copyright 2000-2004 The Apache Software Foundation
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  *
16  */
17 package org.apache.bcel.generic;
18
19 import org.apache.bcel.ExceptionConstants;
20
21 /**
22  * CHECKCAST - Check whether object is of given type
23  * <PRE>Stack: ..., objectref -&gt; ..., objectref</PRE>
24  *
25  * @version $Id: CHECKCAST.java 386056 2006-03-15 11:31:56Z tcurdt $
26  * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
27  */
28 public class CHECKCAST extends CPInstruction implements LoadClass, ExceptionThrower, StackProducer,
29         StackConsumer {
30
31     /**
32      * Empty constructor needed for the Class.newInstance() statement in
33      * Instruction.readInstruction(). 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(int index) {
43         super(org.apache.bcel.Constants.CHECKCAST, index);
44     }
45
46
47     /** @return exceptions this instruction may cause
48      */
49     public Class JavaDoc[] getExceptions() {
50         Class JavaDoc[] cs = new Class JavaDoc[1 + ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length];
51         System.arraycopy(ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION, 0, cs, 0,
52                 ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length);
53         cs[ExceptionConstants.EXCS_CLASS_AND_INTERFACE_RESOLUTION.length] = ExceptionConstants.CLASS_CAST_EXCEPTION;
54         return cs;
55     }
56
57
58     public ObjectType getLoadClassType( ConstantPoolGen cpg ) {
59         Type t = getType(cpg);
60         if (t instanceof ArrayType) {
61             t = ((ArrayType) t).getBasicType();
62         }
63         return (t instanceof ObjectType) ? (ObjectType) t : null;
64     }
65
66
67     /**
68      * Call corresponding visitor method(s). The order is:
69      * Call visitor methods of implemented interfaces first, then
70      * call methods according to the class hierarchy in descending order,
71      * i.e., the most specific visitXXX() call comes last.
72      *
73      * @param v Visitor object
74      */
75     public void accept( 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 }
85
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