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Java > Open Source Codes > prefuse > visual > expression > QueryExpression


1 package prefuse.visual.expression;
2
3 import prefuse.Visualization;
4 import prefuse.data.Schema;
5 import prefuse.data.Tuple;
6 import prefuse.data.search.SearchTupleSet;
7 import prefuse.visual.VisualItem;
8
9 /**
10  * Expression that returns the current query string of a data group of the type
11  * {@link prefuse.data.search.SearchTupleSet}. The data group name is provided
12  * by a String-valued sub-expression.
13  *
14  * @author <a HREF="http://jheer.org">jeffrey heer</a>
15  */
16 public class QueryExpression extends GroupExpression {
17
18     /**
19      * Create a new QueryExpression.
20      */
21     public QueryExpression() {
22         super();
23     }
24     
25     /**
26      * Create a new QueryExpression.
27      * @param group @param group the data group name to use as a parameter
28      */
29     public QueryExpression(String JavaDoc group) {
30         super(group);
31     }
32     
33     /**
34      * @see prefuse.data.expression.Function#getName()
35      */
36     public String JavaDoc getName() {
37         return "QUERY";
38     }
39
40     /**
41      * @see prefuse.data.expression.Expression#getType(prefuse.data.Schema)
42      */
43     public Class JavaDoc getType(Schema s) {
44         return String JavaDoc.class;
45     }
46     
47     /**
48      * @see prefuse.data.expression.Expression#get(prefuse.data.Tuple)
49      */
50     public Object JavaDoc get(Tuple t) {
51         VisualItem item = (VisualItem)t;
52         Visualization vis = item.getVisualization();
53         String JavaDoc group = getGroup(t);
54         SearchTupleSet sts = (SearchTupleSet)vis.getGroup(group);
55         return sts.getQuery();
56     }
57
58 } // end of class QueryExpression
59
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