001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.hivemind.conditional;
016    
017    import org.apache.hivemind.util.Defense;
018    
019    /**
020     * Implementation of {@link org.apache.hivemind.conditional.Node}.
021     * 
022     * @author Howard M. Lewis Ship
023     * @since 1.1
024     */
025    public class NodeImpl implements Node
026    {
027        private Node _left;
028    
029        private Node _right;
030    
031        private Evaluator _evaluator;
032    
033        public NodeImpl(Node left, Node right, Evaluator evaluator)
034        {
035            Defense.notNull(evaluator, "evaluator");
036    
037            _left = left;
038            _right = right;
039            _evaluator = evaluator;
040        }
041    
042        /**
043         * Alternate constructor used for terminal nodes.
044         */
045    
046        public NodeImpl(Evaluator evaluator)
047        {
048            this(null, null, evaluator);
049        }
050    
051        public Node getLeft()
052        {
053            return _left;
054        }
055    
056        public Node getRight()
057        {
058            return _right;
059        }
060    
061        // For testing
062    
063        Evaluator getEvaluator()
064        {
065            return _evaluator;
066        }
067    
068        public boolean evaluate(EvaluationContext context)
069        {
070            return _evaluator.evaluate(context, this);
071        }
072    
073    }