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


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19
20 package org.apache.cayenne.exp.parser;
21
22 import java.util.Iterator JavaDoc;
23
24 import org.apache.cayenne.map.Entity;
25
26 /**
27  * Generic path expression.
28  *
29  * @author Andrus Adamchik
30  * @since 1.1
31  */
32 public abstract class ASTPath extends SimpleNode {
33     protected String JavaDoc path;
34
35     ASTPath(int i) {
36         super(i);
37     }
38
39     public int getOperandCount() {
40         return 1;
41     }
42
43     public Object JavaDoc getOperand(int index) {
44         if (index == 0) {
45             return path;
46         }
47
48         throw new ArrayIndexOutOfBoundsException JavaDoc(index);
49     }
50
51     public void setOperand(int index, Object JavaDoc value) {
52         if (index != 0) {
53             throw new ArrayIndexOutOfBoundsException JavaDoc(index);
54         }
55
56         setPath(value);
57     }
58
59     protected void setPath(Object JavaDoc path) {
60         this.path = (path != null) ? path.toString() : null;
61     }
62
63     protected String JavaDoc getPath() {
64         return path;
65     }
66     
67
68     /**
69      * Helper method to evaluate path expression with Cayenne Entity.
70      */
71     protected Object JavaDoc evaluateEntityNode(Entity entity) {
72         Iterator JavaDoc path = entity.resolvePathComponents(this);
73         Object JavaDoc next = null;
74         while (path.hasNext()) {
75             next = path.next();
76         }
77
78         return next;
79     }
80
81     protected String JavaDoc getExpressionOperator(int index) {
82         throw new UnsupportedOperationException JavaDoc(
83             "No operator for '" + ExpressionParserTreeConstants.jjtNodeName[id] + "'");
84     }
85 }
86
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