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


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
57 /**
58  * IFNULL - Branch if reference is not null
59  *
60  * <PRE>Stack: ..., reference -&gt; ...</PRE>
61  *
62  * @version $Id: IFNULL.java,v 1.1.1.1 2001/10/29 20:00:15 jvanzyl Exp $
63  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
64  */
65 public class IFNULL extends IfInstruction {
66   /**
67    * Empty constructor needed for the Class.newInstance() statement in
68    * Instruction.readInstruction(). Not to be used otherwise.
69    */
70   IFNULL() {}
71
72   public IFNULL(InstructionHandle target) {
73     super(com.sun.org.apache.bcel.internal.Constants.IFNULL, target);
74   }
75
76   /**
77    * @return negation of instruction
78    */
79   public IfInstruction negate() {
80     return new IFNONNULL(target);
81   }
82
83
84   /**
85    * Call corresponding visitor method(s). The order is:
86    * Call visitor methods of implemented interfaces first, then
87    * call methods according to the class hierarchy in descending order,
88    * i.e., the most specific visitXXX() call comes last.
89    *
90    * @param v Visitor object
91    */
92   public void accept(Visitor v) {
93     v.visitStackConsumer(this);
94     v.visitBranchInstruction(this);
95     v.visitIfInstruction(this);
96     v.visitIFNULL(this);
97   }
98 }
99
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