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.spi.Language; 028 029 /** 030 * Abstract base class for Simple languages. 031 */ 032 public abstract class AbstractSimpleLanguage implements Language { 033 034 public Predicate<Exchange> createPredicate(String expression) { 035 return PredicateBuilder.toPredicate(createExpression(expression)); 036 } 037 038 public Expression<Exchange> createExpression(String expression) { 039 if (expression.indexOf("${") >= 0) { 040 return createComplexExpression(expression); 041 } 042 return createSimpleExpression(expression); 043 } 044 045 protected Expression<Exchange> createComplexExpression(String expression) { 046 List<Expression> results = new ArrayList<Expression>(); 047 048 int pivot = 0; 049 int size = expression.length(); 050 while (pivot < size) { 051 int idx = expression.indexOf("${", pivot); 052 if (idx < 0) { 053 results.add(createConstantExpression(expression, pivot, size)); 054 break; 055 } else { 056 if (pivot < idx) { 057 results.add(createConstantExpression(expression, pivot, idx)); 058 } 059 pivot = idx + 2; 060 int endIdx = expression.indexOf("}", pivot); 061 if (endIdx < 0) { 062 throw new IllegalArgumentException("Expecting } but found end of string for simple expression: " + expression); 063 } 064 String simpleText = expression.substring(pivot, endIdx); 065 066 Expression simpleExpression = createSimpleExpression(simpleText); 067 results.add(simpleExpression); 068 pivot = endIdx + 1; 069 } 070 } 071 return ExpressionBuilder.concatExpression(results, expression); 072 } 073 074 protected Expression createConstantExpression(String expression, int start, int end) { 075 return ExpressionBuilder.constantExpression(expression.substring(start, end)); 076 } 077 078 /** 079 * Creates the simple expression based on the extracted content from the ${ } place holders 080 * 081 * @param expression the content between ${ and } 082 * @return the expression 083 */ 084 protected abstract <E extends Exchange> Expression<Exchange> createSimpleExpression(String expression); 085 086 protected String ifStartsWithReturnRemainder(String prefix, String text) { 087 if (text.startsWith(prefix)) { 088 String remainder = text.substring(prefix.length()); 089 if (remainder.length() > 0) { 090 return remainder; 091 } 092 } 093 return null; 094 } 095 }