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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
6    * under the terms of the GNU General Public License version 2 only, as
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       */
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       */
49      public boolean equals(int i) {
50          return i == 0;
51      }
52  
53      public boolean isNull() {
54          return true;
55      }
56  
57      /**
58       * Code
59       */
60      public void codeValue(Environment env, Context ctx, Assembler asm) {
61          asm.add(where, opc_aconst_null);
62      }
63  
64      /**
65       * Print
66       */
67      public void print(PrintStream out) {
68          out.print("null");
69      }
70  }