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 */ 017package org.apache.camel.language.ref; 018 019import org.apache.camel.Exchange; 020import org.apache.camel.Expression; 021import org.apache.camel.IsSingleton; 022import org.apache.camel.Predicate; 023import org.apache.camel.builder.ExpressionBuilder; 024import org.apache.camel.spi.Language; 025import org.apache.camel.support.ExpressionAdapter; 026import org.apache.camel.util.ExpressionToPredicateAdapter; 027 028/** 029 * A language for referred expressions. 030 */ 031public class RefLanguage implements Language, IsSingleton { 032 033 public static Expression ref(Object value) { 034 String ref = value.toString(); 035 return ExpressionBuilder.refExpression(ref); 036 } 037 038 public Predicate createPredicate(String expression) { 039 return ExpressionToPredicateAdapter.toPredicate(createExpression(expression)); 040 } 041 042 public Expression createExpression(final String expression) { 043 final Expression exp = RefLanguage.ref(expression); 044 return new ExpressionAdapter() { 045 public Object evaluate(Exchange exchange) { 046 Expression lookup = exp.evaluate(exchange, Expression.class); 047 if (lookup != null) { 048 return lookup.evaluate(exchange, Object.class); 049 } else { 050 throw new IllegalArgumentException("Cannot find expression in registry with ref: " + expression); 051 } 052 } 053 054 public String toString() { 055 return exp.toString(); 056 } 057 }; 058 } 059 060 public boolean isSingleton() { 061 return true; 062 } 063}