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.Predicate;
022 import org.apache.camel.builder.ExpressionBuilder;
023 import org.apache.camel.builder.PredicateBuilder;
024 import org.apache.camel.language.IllegalSyntaxException;
025 import org.apache.camel.spi.Language;
026 import org.apache.camel.util.ObjectHelper;
027
028 /**
029 * A <a href="http://activemq.apache.org/camel/simple.html>simple language</a>
030 * which maps simple property style notations to acces headers and bodies.
031 * Examples of supported expressions are <p/>
032 * <ul>
033 * <li>in.header.foo or header.foo to access an inbound header called 'foo'</li>
034 * <li>in.body or body to access the inbound body</li>
035 * <li>out.header.foo to access an outbound header called 'foo'</li>
036 * <li>out.body to access the inbound body</li>
037 * <li>property.foo to access the exchange property called 'foo'</li>
038 * <li>sys.foo to access the system property called 'foo'</li>
039 * </ul>
040 *
041 * @version $Revision: $
042 */
043 public class SimpleLanguage implements Language {
044
045 public Predicate<Exchange> createPredicate(String expression) {
046 return PredicateBuilder.toPredicate(createExpression(expression));
047 }
048
049 public Expression<Exchange> createExpression(String expression) {
050 if (ObjectHelper.isEqualToAny(expression, "body", "in.body")) {
051 return ExpressionBuilder.bodyExpression();
052 } else if (ObjectHelper.equals(expression, "out.body")) {
053 return ExpressionBuilder.outBodyExpression();
054 }
055 String remainder = ifStartsWithReturnRemainder("in.header.", expression);
056 if (remainder == null) {
057 remainder = ifStartsWithReturnRemainder("header.", expression);
058 }
059 if (remainder != null) {
060 return ExpressionBuilder.headerExpression(remainder);
061 }
062 remainder = ifStartsWithReturnRemainder("out.header.", expression);
063 if (remainder != null) {
064 return ExpressionBuilder.outHeaderExpression(remainder);
065 }
066 remainder = ifStartsWithReturnRemainder("property.", expression);
067 if (remainder != null) {
068 return ExpressionBuilder.propertyExpression(remainder);
069 }
070 remainder = ifStartsWithReturnRemainder("sys.", expression);
071 if (remainder != null) {
072 return ExpressionBuilder.propertyExpression(remainder);
073 }
074 throw new IllegalSyntaxException(this, expression);
075 }
076
077 protected String ifStartsWithReturnRemainder(String prefix, String text) {
078 if (text.startsWith(prefix)) {
079 String remainder = text.substring(prefix.length());
080 if (remainder.length() > 0) {
081
082 return remainder;
083 }
084 }
085 return null;
086 }
087 }