/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.struts2.jasper.el;

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.ELParseException;
import javax.servlet.jsp.el.Expression;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.FunctionMapper;
import javax.servlet.jsp.el.VariableResolver;


public final class ExpressionEvaluatorImpl extends ExpressionEvaluator {

	private final ExpressionFactory factory;
	
	public ExpressionEvaluatorImpl(ExpressionFactory factory) {
		this.factory = factory;
	}

	public Expression parseExpression(String expression, Class expectedType,
			FunctionMapper fMapper) throws ELException {
		try {
			ELContextImpl ctx = new ELContextImpl(ELResolverImpl.DefaultResolver);
            if (fMapper != null) {
                ctx.setFunctionMapper(new FunctionMapperImpl(fMapper));
            }
			ValueExpression ve = this.factory.createValueExpression(ctx, expression, expectedType);
			return new ExpressionImpl(ve);
		} catch (javax.el.ELException e) {
			throw new ELParseException(e.getMessage());
		}
	}

	public Object evaluate(String expression, Class expectedType,
			VariableResolver vResolver, FunctionMapper fMapper)
			throws ELException {
		return this.parseExpression(expression, expectedType, fMapper).evaluate(vResolver);
	}

}
