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.language.simple;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Expression;
021    import org.apache.camel.builder.ExpressionBuilder;
022    import org.apache.camel.language.IllegalSyntaxException;
023    import org.apache.camel.util.ObjectHelper;
024    
025    /**
026     * A <a href="http://activemq.apache.org/camel/simple.html">simple language</a>
027     * which maps simple property style notations to access headers and bodies.
028     * Examples of supported expressions are:
029     * <ul>
030     * <li>id to access the inbound message Id</li>
031     * <li>in.body or body to access the inbound body</li>
032     * <li>out.body to access the inbound body</li>
033     * <li>in.header.foo or header.foo to access an inbound header called 'foo'</li>
034     * <li>out.header.foo to access an outbound header called 'foo'</li>
035     * <li>property.foo to access the exchange property called 'foo'</li>
036     * <li>sys.foo to access the system property called 'foo'</li>
037     * </ul>
038     *
039     * @version $Revision: 47086 $
040     */
041    public class SimpleLanguage extends AbstractSimpleLanguage {
042    
043        public static Expression simple(String expression) {
044            SimpleLanguage language = new SimpleLanguage();
045            return language.createExpression(expression);
046        }
047    
048        protected Expression<Exchange> createSimpleExpression(String expression) {
049            if (ObjectHelper.isEqualToAny(expression, "body", "in.body")) {
050                return ExpressionBuilder.bodyExpression();
051            } else if (ObjectHelper.equal(expression, "out.body")) {
052                return ExpressionBuilder.outBodyExpression();
053            } else if (ObjectHelper.equal(expression, "id")) {
054                return ExpressionBuilder.messageIdExpression();
055            }
056    
057            // in header expression
058            String remainder = ifStartsWithReturnRemainder("in.header.", expression);
059            if (remainder == null) {
060                remainder = ifStartsWithReturnRemainder("header.", expression);
061            }
062            if (remainder == null) {
063                remainder = ifStartsWithReturnRemainder("headers.", expression);
064            }
065            if (remainder == null) {
066                remainder = ifStartsWithReturnRemainder("in.headers.", expression);
067            }
068            if (remainder != null) {
069                return ExpressionBuilder.headerExpression(remainder);
070            }
071    
072            // out header expression
073            remainder = ifStartsWithReturnRemainder("out.header.", expression);
074            if (remainder == null) {
075                remainder = ifStartsWithReturnRemainder("out.headers.", expression);
076            }
077            if (remainder != null) {
078                return ExpressionBuilder.outHeaderExpression(remainder);
079            }
080    
081            // property
082            remainder = ifStartsWithReturnRemainder("property.", expression);
083            if (remainder != null) {
084                return ExpressionBuilder.propertyExpression(remainder);
085            }
086    
087            // system property
088            remainder = ifStartsWithReturnRemainder("sys.", expression);
089            if (remainder != null) {
090                return ExpressionBuilder.systemProperty(remainder);
091            }
092    
093            throw new IllegalSyntaxException(this, expression);
094        }
095    
096    }