001/* 002 * (C) Copyright 2006-2008 Nuxeo SA (http://nuxeo.com/) and others. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 * 016 * Contributors: 017 * Nuxeo - initial API and implementation 018 * 019 * $Id$ 020 */ 021 022package org.nuxeo.ecm.platform.el; 023 024import javax.el.ELContext; 025import javax.el.ExpressionFactory; 026 027public class ExpressionEvaluator { 028 029 protected ExpressionEvaluator() { 030 } 031 032 public ExpressionEvaluator(ExpressionFactory factory) { 033 expressionFactory = factory; 034 } 035 036 protected ExpressionFactory expressionFactory; 037 038 public void setExpressionFactory(ExpressionFactory expressionFactory) { 039 this.expressionFactory = expressionFactory; 040 } 041 042 public <T> T evaluateExpression(ELContext context, String stringExpression, Class<T> clazz) { 043 return clazz.cast(expressionFactory.createValueExpression(context, stringExpression, clazz).getValue(context)); 044 } 045 046 public void bindValue(ELContext context, String name, Object value) { 047 if (value == null) { 048 throw new IllegalArgumentException("No value provided, cannot bind " + name + " in context " + context); 049 } 050 // the jsf/facelets way of binding additional values in the context 051 // is to contribute a variable mapper wrapping the existing one, so 052 // that contexts are not merged and variables are not overridden, 053 // especially when the variable mapper is used in a shared context => 054 // maybe change this behaviour if needed 055 context.getVariableMapper().setVariable(name, expressionFactory.createValueExpression(value, value.getClass())); 056 } 057 058}