001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel;
018    
019    /**
020     * Evaluates a binary <a
021     * href="http://activemq.apache.org/camel/predicate.html">predicate</a> on the
022     * message exchange to support things like <a
023     * href="http://activemq.apache.org/camel/scripting-languages.html">scripting
024     * languages</a>, <a href="http://activemq.apache.org/camel/xquery.html">XQuery</a>
025     * or <a href="http://activemq.apache.org/camel/sql.html">SQL</a> as well as
026     * any arbitrary Java expression.
027     * 
028     * @version $Revision: 630591 $
029     */
030    public interface Predicate<E> {
031    
032        /**
033         * Evaluates the predicate on the message exchange and returns true if this
034         * exchange matches the predicate
035         * 
036         * @param exchange the message exchange
037         * @return true if the predicate matches
038         */
039        boolean matches(E exchange);
040    
041        /**
042         * Allows this predicate to be used nicely in testing to generate a nicely
043         * formatted exception and message if this predicate does not match for the
044         * given exchange.
045         * 
046         * @param text the description to use in the exception message
047         * @param exchange the exchange to evaluate the expression on
048         * @throws AssertionError if the predicate does not match
049         */
050        void assertMatches(String text, E exchange) throws AssertionError;
051    
052    }