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


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19
20 package org.apache.cayenne.exp.parser;
21
22 import org.apache.commons.collections.Transformer;
23 import org.apache.cayenne.exp.ExpressionException;
24
25 /**
26  * Superclass of aggregated conditional nodes such as NOT, AND, OR. Performs
27  * extra checks on parent and child expressions to validate conditions that
28  * are not addressed in the Cayenne expressions grammar.
29  *
30  * @since 1.1
31  * @author Andrus Adamchik
32  */
33 public abstract class AggregateConditionNode extends SimpleNode {
34     AggregateConditionNode(int i) {
35         super(i);
36     }
37
38     protected boolean pruneNodeForPrunedChild(Object JavaDoc prunedChild) {
39         return false;
40     }
41
42     protected Object JavaDoc transformExpression(Transformer transformer) {
43         Object JavaDoc transformed = super.transformExpression(transformer);
44
45         if (!(transformed instanceof AggregateConditionNode)) {
46             return transformed;
47         }
48         
49         AggregateConditionNode condition = (AggregateConditionNode) transformed;
50
51         // prune itself if the transformation resulted in
52 // no children or a single child
53 switch (condition.getOperandCount()) {
54             case 1 :
55                 return condition.getOperand(0);
56             case 0 :
57                 return PRUNED_NODE;
58             default :
59                 return condition;
60         }
61     }
62
63     public void jjtSetParent(Node n) {
64         // this is a check that we can't handle properly
65 // in the grammar... do it here...
66
67         // disallow non-aggregated condition parents...
68 if (!(n instanceof AggregateConditionNode)) {
69             String JavaDoc label =
70                 (n instanceof SimpleNode)
71                     ? ((SimpleNode) n).expName()
72                     : String.valueOf(n);
73             throw new ExpressionException(expName() + ": invalid parent - " + label);
74         }
75
76         super.jjtSetParent(n);
77     }
78
79     public void jjtAddChild(Node n, int i) {
80         // this is a check that we can't handle properly
81 // in the grammar... do it here...
82
83         // only allow conditional nodes...no scalars
84 if (!(n instanceof ConditionNode) && !(n instanceof AggregateConditionNode)) {
85             String JavaDoc label =
86                 (n instanceof SimpleNode)
87                     ? ((SimpleNode) n).expName()
88                     : String.valueOf(n);
89             throw new ExpressionException(expName() + ": invalid child - " + label);
90         }
91
92         super.jjtAddChild(n, i);
93     }
94 }
95
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