/*
 * Copyright 2004-2008 the original author or authors.
 *
 * Licensed 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.springframework.expression.common;

import org.springframework.expression.EvaluationContext;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.TypeConverter;
import org.springframework.expression.TypeUtils;

/**
 * Common utility functions that may be used by any Expression Language provider.
 *
 * @author Andy Clement
 */
public class ExpressionUtils {

	/**
	 * Determines if there is a type converter available in the specified context and attempts to use it to convert the supplied
	 * value to the specified type.  Throws an exception if conversion is not possible.
	 * 
	 * @param context the evaluation context that may define a type converter
	 * @param value the value to convert (may be null)
	 * @param toType the type to attempt conversion to
	 * @return the converted value
	 * @throws EvaluationException if there is a problem during conversion or conversion of the value to the specified type is not supported
	 */
	public static Object convert(EvaluationContext context, Object value, Class<?> toType) throws EvaluationException {
		if (value==null || toType.isAssignableFrom(value.getClass())) {
			return value;
		}
		if (context!=null) {
			TypeUtils typeUtils = context.getTypeUtils();
			if (typeUtils != null) {
				TypeConverter typeConverter = typeUtils.getTypeConverter();
				return typeConverter.convertValue(value,toType);
			}
		}
		throw new EvaluationException("Cannot convert value '"+value+"' to type '"+toType.getName()+"'");
	}

}

@@ -965,24 +965,25 @@
 provider.%0A *
+ 
 %0A * @author 
@@ -1152,16 +1152,20 @@
 vert the
+%0A%09 *
  supplie
@@ -1165,20 +1165,16 @@
 supplied
-%0A%09 *
  value t
@@ -1194,17 +1194,16 @@
 ed type.
- 
  Throws 
@@ -1573,24 +1573,28 @@
 he specified
+%0A%09 *
  type is not
@@ -1741,10 +1741,30 @@
 alue
+ 
 ==
+ null %7C%7C toType == 
 null
@@ -1846,18 +1846,20 @@
 (context
+ 
 !=
+ 
 null) %7B%0A
@@ -2043,16 +2043,17 @@
 e(value,
+ 
 toType);
@@ -2122,15 +2122,19 @@
 e '%22
-+
+ + 
 value
-+
+ + 
 %22' t
@@ -2142,17 +2142,19 @@
  type '%22
-+
+ + 
 toType.g
@@ -2161,17 +2161,19 @@
 etName()
-+
+ + 
 %22'%22);%0A%09%7D

allow for undefined target type