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 java.util.ArrayList; 020 import java.util.List; 021 022 import org.apache.camel.Exchange; 023 import org.apache.camel.Expression; 024 import org.apache.camel.Predicate; 025 import org.apache.camel.builder.ExpressionBuilder; 026 import org.apache.camel.builder.PredicateBuilder; 027 import org.apache.camel.language.IllegalSyntaxException; 028 import org.apache.camel.spi.Language; 029 import org.apache.camel.util.ObjectHelper; 030 031 /** 032 * A <a href="http://activemq.apache.org/camel/simple.html>simple language</a> 033 * which maps simple property style notations to access headers and bodies. 034 * Examples of supported expressions are <p/> 035 * <ul> 036 * <li>in.header.foo or header.foo to access an inbound header called 'foo'</li> 037 * <li>in.body or body to access the inbound body</li> 038 * <li>out.header.foo to access an outbound header called 'foo'</li> 039 * <li>out.body to access the inbound body</li> 040 * <li>property.foo to access the exchange property called 'foo'</li> 041 * <li>sys.foo to access the system property called 'foo'</li> 042 * </ul> 043 * 044 * @version $Revision: 40913 $ 045 */ 046 public class SimpleLanguage implements Language { 047 048 public static Expression simple(String expression) { 049 SimpleLanguage language = new SimpleLanguage(); 050 return language.createExpression(expression); 051 } 052 053 public Predicate<Exchange> createPredicate(String expression) { 054 return PredicateBuilder.toPredicate(createExpression(expression)); 055 } 056 057 public Expression<Exchange> createExpression(String expression) { 058 if (expression.indexOf("${") >= 0) { 059 return createComplexExpression(expression); 060 } 061 return createSimpleExpression(expression); 062 } 063 064 protected Expression<Exchange> createComplexExpression(String expression) { 065 List<Expression> results = new ArrayList<Expression>(); 066 067 int pivot = 0; 068 int size = expression.length(); 069 while (pivot < size) { 070 int idx = expression.indexOf("${", pivot); 071 if (idx < 0) { 072 results.add(createConstantExpression(expression, pivot, size)); 073 break; 074 } else { 075 if (pivot < idx) { 076 results.add(createConstantExpression(expression, pivot, idx)); 077 } 078 pivot = idx + 2; 079 int endIdx = expression.indexOf("}", pivot); 080 if (endIdx < 0) { 081 throw new IllegalArgumentException("Expecting } but found end of string for simple expression: " + expression); 082 } 083 String simpleText = expression.substring(pivot, endIdx); 084 085 Expression simpleExpression = createSimpleExpression(simpleText); 086 results.add(simpleExpression); 087 pivot = endIdx + 1; 088 } 089 } 090 return ExpressionBuilder.concatExpression(results, expression); 091 } 092 093 protected Expression createConstantExpression(String expression, int start, int end) { 094 return ExpressionBuilder.constantExpression(expression.substring(start, end)); 095 } 096 097 protected Expression<Exchange> createSimpleExpression(String expression) { 098 if (ObjectHelper.isEqualToAny(expression, "body", "in.body")) { 099 return ExpressionBuilder.bodyExpression(); 100 } else if (ObjectHelper.equal(expression, "out.body")) { 101 return ExpressionBuilder.outBodyExpression(); 102 } 103 104 // in header expression 105 String remainder = ifStartsWithReturnRemainder("in.header.", expression); 106 if (remainder == null) { 107 remainder = ifStartsWithReturnRemainder("header.", expression); 108 } 109 if (remainder == null) { 110 remainder = ifStartsWithReturnRemainder("headers.", expression); 111 } 112 if (remainder == null) { 113 remainder = ifStartsWithReturnRemainder("in.headers.", expression); 114 } 115 if (remainder != null) { 116 return ExpressionBuilder.headerExpression(remainder); 117 } 118 119 // out header expression 120 remainder = ifStartsWithReturnRemainder("out.header.", expression); 121 if (remainder == null) { 122 remainder = ifStartsWithReturnRemainder("out.headers.", expression); 123 } 124 if (remainder != null) { 125 return ExpressionBuilder.outHeaderExpression(remainder); 126 } 127 128 // property 129 remainder = ifStartsWithReturnRemainder("property.", expression); 130 if (remainder != null) { 131 return ExpressionBuilder.propertyExpression(remainder); 132 } 133 134 // system property 135 remainder = ifStartsWithReturnRemainder("sys.", expression); 136 if (remainder != null) { 137 return ExpressionBuilder.propertyExpression(remainder); 138 } 139 throw new IllegalSyntaxException(this, expression); 140 } 141 142 protected String ifStartsWithReturnRemainder(String prefix, String text) { 143 if (text.startsWith(prefix)) { 144 String remainder = text.substring(prefix.length()); 145 if (remainder.length() > 0) { 146 return remainder; 147 } 148 } 149 return null; 150 } 151 }