001    /*
002     * Copyright 2010 the original author or authors.
003     * 
004     *  Licensed under the Apache License, Version 2.0 (the "License");
005     *  you may not use this file except in compliance with the License.
006     *  You may obtain a copy of the License at
007     *
008     *      http://www.apache.org/licenses/LICENSE-2.0
009     *
010     *  Unless required by applicable law or agreed to in writing, software
011     *  distributed under the License is distributed on an "AS IS" BASIS,
012     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     *  See the License for the specific language governing permissions and
014     *  limitations under the License.
015     */
016    package com.hs.mail.imap.message.search;
017    
018    /**
019     * Search criteria are expressed as a tree of search-keys, forming a parse-tree
020     * for the search expression.
021     * <p>
022     * 
023     * Search-keys are represented by this class. This is an abstract class;
024     * subclasses implement specific data structures. <p>
025     * 
026     * @author Won Chul Doh
027     * @since Jan 30, 2010
028     * 
029     */
030    public abstract class SearchKey {
031    
032            public abstract boolean isComposite();
033    
034    }