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Java > Open Source Codes > org > jacorb > trading > constraint > ExistNode


1
2 // Copyright (C) 1998-1999
3 // Object Oriented Concepts, Inc.
4
5 // **********************************************************************
6 //
7 // Copyright (c) 1997
8 // Mark Spruiell (mark@intellisoft.com)
9 //
10 // See the COPYING file for more information
11 //
12 // **********************************************************************
13
14 package org.jacorb.trading.constraint;
15
16 import java.io.*;
17
18
19 /** Determines if a property exists */
20 public class ExistNode extends ExprNode
21 {
22   private ExprNode m_child;
23
24
25   private ExistNode()
26   {
27   }
28
29
30   public ExistNode(ExprNode child)
31   {
32     m_child = child;
33
34     setType(new ValueType(ValueType.BOOLEAN));
35   }
36
37
38   public void print(PrintStream ps)
39   {
40     ps.println("ExistNode: type = " + getType());
41     ps.println("Child node:");
42     m_child.print(ps);
43   }
44
45
46   public Value evaluate(PropertySource source)
47     throws MissingPropertyException
48   {
49     Value result = null;
50
51     PropertyNode node = (PropertyNode)m_child;
52     result = ValueFactory.createBoolean(node.exists(source));
53
54     return result;
55   }
56 }
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