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Java > Open Source Codes > org > apache > hivemind > conditional > Evaluator


1 // Copyright 2004, 2005 The Apache Software Foundation
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 package org.apache.hivemind.conditional;
16
17 /**
18  * An evaluator is paired with a {@link Node}. The Node provides structure, the Evaluator provides
19  * meaning, interpreting the node.
20  *
21  * @author Howard M. Lewis Ship
22  * @since 1.1
23  */
24 public interface Evaluator
25 {
26     /**
27      * Invoked by the Node to evaluate its own value. Typical implementations will extract the
28      * Node's {@link org.apache.hivemind.conditional.Node#getLeft() left} and
29      * {@link org.apache.hivemind.conditional.Node#getRight() right} properties and combine or
30      * otherwise evaluate them. Terminal nodes in the tree will have evaluators that don't do that
31      * but generate a return value internally.
32      */
33
34     public boolean evaluate(EvaluationContext context, Node node);
35 }
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