1 /*
2  * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
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7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package sun.tools.tree;
27 
28 import sun.tools.java.*;
29 import sun.tools.asm.Assembler;
30 import java.io.PrintStream;
31 
32 /**
33  * WARNING: The contents of this source file are not part of any
34  * supported API.  Code that depends on them does so at its own risk:
35  * they are subject to change or removal without notice.
36  */
37 public
38 class NullExpression extends ConstantExpression {
39     /**
40      * Constructor
41      */
NullExpression(long where)42     public NullExpression(long where) {
43         super(NULL, where, Type.tNull);
44     }
45 
46     /**
47      * Check if the expression is equal to a value
48      */
equals(int i)49     public boolean equals(int i) {
50         return i == 0;
51     }
52 
isNull()53     public boolean isNull() {
54         return true;
55     }
56 
57     /**
58      * Code
59      */
codeValue(Environment env, Context ctx, Assembler asm)60     public void codeValue(Environment env, Context ctx, Assembler asm) {
61         asm.add(where, opc_aconst_null);
62     }
63 
64     /**
65      * Print
66      */
print(PrintStream out)67     public void print(PrintStream out) {
68         out.print("null");
69     }
70 }
71