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
015package org.apache.hivemind.conditional;
016
017import 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 */
025public 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}