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     * <li>date:&lt;command&gt;:&lt;pattern&gt; for date formatting using the {@link java.text.SimpleDateFormat} patterns.
038     *     Supported commands are: <tt>now</tt> for current timestamp,
039     *     <tt>in.header.xxx</tt> or <tt>header.xxx</tt> to use the Date object in the in header.
040     *     <tt>out.header.xxx</tt> to use the Date object in the out header.
041     * </li>
042     * <li>bean:&lt;bean expression&gt; to invoke a bean using the
043     * {@link org.apache.camel.language.bean.BeanLanguage BeanLanguage}</li>
044     * </ul>
045     *
046     * @version $Revision: 52207 $
047     */
048    public class SimpleLanguage extends AbstractSimpleLanguage {
049    
050        public static Expression simple(String expression) {
051            SimpleLanguage language = new SimpleLanguage();
052            return language.createExpression(expression);
053        }
054    
055        protected Expression<Exchange> createSimpleExpression(String expression) {
056            if (ObjectHelper.isEqualToAny(expression, "body", "in.body")) {
057                return ExpressionBuilder.bodyExpression();
058            } else if (ObjectHelper.equal(expression, "out.body")) {
059                return ExpressionBuilder.outBodyExpression();
060            } else if (ObjectHelper.equal(expression, "id")) {
061                return ExpressionBuilder.messageIdExpression();
062            }
063    
064            // in header expression
065            String remainder = ifStartsWithReturnRemainder("in.header.", expression);
066            if (remainder == null) {
067                remainder = ifStartsWithReturnRemainder("header.", expression);
068            }
069            if (remainder == null) {
070                remainder = ifStartsWithReturnRemainder("headers.", expression);
071            }
072            if (remainder == null) {
073                remainder = ifStartsWithReturnRemainder("in.headers.", expression);
074            }
075            if (remainder != null) {
076                return ExpressionBuilder.headerExpression(remainder);
077            }
078    
079            // out header expression
080            remainder = ifStartsWithReturnRemainder("out.header.", expression);
081            if (remainder == null) {
082                remainder = ifStartsWithReturnRemainder("out.headers.", expression);
083            }
084            if (remainder != null) {
085                return ExpressionBuilder.outHeaderExpression(remainder);
086            }
087    
088            // property
089            remainder = ifStartsWithReturnRemainder("property.", expression);
090            if (remainder != null) {
091                return ExpressionBuilder.propertyExpression(remainder);
092            }
093    
094            // system property
095            remainder = ifStartsWithReturnRemainder("sys.", expression);
096            if (remainder != null) {
097                return ExpressionBuilder.systemProperty(remainder);
098            }
099    
100            // date: prefix
101            remainder = ifStartsWithReturnRemainder("date:", expression);
102            if (remainder != null) {
103                String[] parts = remainder.split(":");
104                if (parts.length != 2) {
105                    throw new IllegalSyntaxException(this, expression + " ${date:command:pattern} is the correct syntax.");
106                }
107                String command = parts[0];
108                String pattern = parts[1];
109                return ExpressionBuilder.dateExpression(command, pattern);
110            }
111    
112            // bean: prefix
113            remainder = ifStartsWithReturnRemainder("bean:", expression);
114            if (remainder != null) {
115                return ExpressionBuilder.beanExpression(remainder);
116            }
117    
118            throw new IllegalSyntaxException(this, expression);
119        }
120    
121    }