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


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56 package org.objectstyle.cayenne.exp.parser;
57
58 import org.objectstyle.cayenne.exp.Expression;
59 import org.objectstyle.cayenne.util.ConversionUtil;
60
61 /**
62  * "Less Then" expression.
63  *
64  * @since 1.1
65  * @author Andrei Adamchik
66  */
67 public class ASTLess extends ConditionNode {
68     /**
69      * Constructor used by expression parser. Do not invoke directly.
70      */
71     ASTLess(int id) {
72         super(id);
73     }
74
75     public ASTLess() {
76         super(ExpressionParserTreeConstants.JJTLESS);
77     }
78
79     public ASTLess(ASTPath path, Object JavaDoc value) {
80         super(ExpressionParserTreeConstants.JJTLESS);
81         jjtAddChild(path, 0);
82         jjtAddChild(new ASTScalar(value), 1);
83     }
84
85     protected Object JavaDoc evaluateNode(Object JavaDoc o) throws Exception JavaDoc {
86         int len = jjtGetNumChildren();
87         if (len != 2) {
88             return Boolean.FALSE;
89         }
90
91         Comparable JavaDoc c1 = ConversionUtil.toComparable(evaluateChild(0, o));
92         if (c1 == null) {
93             return Boolean.FALSE;
94         }
95
96         Comparable JavaDoc c2 = ConversionUtil.toComparable(evaluateChild(1, o));
97         if (c2 == null) {
98             return Boolean.FALSE;
99         }
100
101         return c1.compareTo(c2) < 0 ? Boolean.TRUE : Boolean.FALSE;
102     }
103
104     /**
105      * Creates a copy of this expression node, without copying children.
106      */
107     public Expression shallowCopy() {
108         return new ASTLess(id);
109     }
110
111     protected String JavaDoc getExpressionOperator(int index) {
112         return "<";
113     }
114
115     public int getType() {
116         return Expression.LESS_THAN;
117     }
118 }
119
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