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 */
017package org.apache.camel.support;
018
019import org.apache.camel.Exchange;
020
021/**
022 * A helper class for developers wishing to implement an {@link org.apache.camel.Expression}
023 * using Java code with a minimum amount of code to write so that the developer only needs
024 * to implement one of the {@link #evaluate(org.apache.camel.Exchange, Class)} or
025 * {@link #evaluate(org.apache.camel.Exchange)} methods.
026 *
027 * @version 
028 */
029public abstract class ExpressionAdapter extends ExpressionSupport {
030
031    protected String assertionFailureMessage(Exchange exchange) {
032        return toString();
033    }
034
035    public <T> T evaluate(Exchange exchange, Class<T> type) {
036        Object value = evaluate(exchange);
037        if (Object.class == type) {
038            // do not use type converter if type is Object (optimize)
039            return (T) value;
040        }
041        return exchange.getContext().getTypeConverter().convertTo(type, exchange, value);
042    }
043
044}