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    /**
018     * An AST node in the tree parsed from the conditional expression. Nodes form a binary tree, each
019     * node may have a left and a right sub-node.
020     * 
021     * @author Howard M. Lewis Ship
022     * @since 1.1
023     */
024    public interface Node
025    {
026        public Node getLeft();
027    
028        public Node getRight();
029    
030        /**
031         * Evaluates the nodes using the context to provide access to runtime information.
032         */
033        public boolean evaluate(EvaluationContext context);
034    }