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Java > Open Source Codes > prefuse > data > expression > ExpressionVisitor


1 package prefuse.data.expression;
2
3 /**
4  * Visitor interface for objects that visit each sub-expression of an
5  * Expression instance, performing some computation or data collection.
6  *
7  * @author <a HREF="http://jheer.org">jeffrey heer</a>
8  */
9 public interface ExpressionVisitor {
10
11     /**
12      * Callback made when visiting a particular expression.
13      * @param expr the expression currently being visited.
14      */
15     public void visitExpression(Expression expr);
16     
17     /**
18      * Callback to signal that the visitor has just descended
19      * a level in the Expression tree.
20      */
21     public void down();
22     
23     /**
24      * Callback to signal that the visitor has just ascended
25      * a level in the Expression tree.
26      */
27     public void up();
28     
29 } // end of interface ExpressionVisitor
30
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