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Java > Open Source Codes > org > apache > cayenne > exp > parser > ASTLess


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19
20 package org.apache.cayenne.exp.parser;
21
22 import org.apache.cayenne.exp.Expression;
23 import org.apache.cayenne.util.ConversionUtil;
24
25 /**
26  * "Less Then" expression.
27  *
28  * @since 1.1
29  * @author Andrus Adamchik
30  */
31 public class ASTLess extends ConditionNode {
32     /**
33      * Constructor used by expression parser. Do not invoke directly.
34      */
35     ASTLess(int id) {
36         super(id);
37     }
38
39     public ASTLess() {
40         super(ExpressionParserTreeConstants.JJTLESS);
41     }
42
43     public ASTLess(ASTPath path, Object JavaDoc value) {
44         super(ExpressionParserTreeConstants.JJTLESS);
45         jjtAddChild(path, 0);
46         jjtAddChild(new ASTScalar(value), 1);
47     }
48
49     protected Object JavaDoc evaluateNode(Object JavaDoc o) throws Exception JavaDoc {
50         int len = jjtGetNumChildren();
51         if (len != 2) {
52             return Boolean.FALSE;
53         }
54
55         Comparable JavaDoc c1 = ConversionUtil.toComparable(evaluateChild(0, o));
56         if (c1 == null) {
57             return Boolean.FALSE;
58         }
59
60         Comparable JavaDoc c2 = ConversionUtil.toComparable(evaluateChild(1, o));
61         if (c2 == null) {
62             return Boolean.FALSE;
63         }
64
65         return c1.compareTo(c2) < 0 ? Boolean.TRUE : Boolean.FALSE;
66     }
67
68     /**
69      * Creates a copy of this expression node, without copying children.
70      */
71     public Expression shallowCopy() {
72         return new ASTLess(id);
73     }
74
75     protected String JavaDoc getExpressionOperator(int index) {
76         return "<";
77     }
78
79     public int getType() {
80         return Expression.LESS_THAN;
81     }
82 }
83
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