/*
* Copyright 2002-2007 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.util;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;
/**
* Utility to work with Java 5 generic type parameters.
* Mainly for internal use within the framework.
*
* @author Ramnivas Laddad
* @author Juergen Hoeller
* @since 2.0.7
*/
public abstract class TypeUtils {
/**
* Check if the right-hand side type may be assigned to the left-hand side
* type following the Java generics rules.
* @param lhsType the target type
* @param rhsType the value type that should be assigned to the target type
* @return true if rhs is assignable to lhs
*/
public static boolean isAssignable(Type lhsType, Type rhsType) {
Assert.notNull(lhsType, "Left-hand side type must not be null");
Assert.notNull(rhsType, "Right-hand side type must not be null");
if (lhsType.equals(rhsType)) {
return true;
}
if (lhsType instanceof Class && rhsType instanceof Class) {
return ClassUtils.isAssignable((Class) lhsType, (Class) rhsType);
}
if (lhsType instanceof ParameterizedType && rhsType instanceof ParameterizedType) {
return isAssignable((ParameterizedType) lhsType, (ParameterizedType) rhsType);
}
if (lhsType instanceof WildcardType) {
return isAssignable((WildcardType) lhsType, rhsType);
}
return false;
}
private static boolean isAssignable(ParameterizedType lhsType, ParameterizedType rhsType) {
if (lhsType.equals(rhsType)) {
return true;
}
Type[] lhsTypeArguments = lhsType.getActualTypeArguments();
Type[] rhsTypeArguments = rhsType.getActualTypeArguments();
if (lhsTypeArguments.length != rhsTypeArguments.length) {
return false;
}
for (int size = lhsTypeArguments.length, i = 0; i < size; ++i) {
Type lhsArg = lhsTypeArguments[i];
Type rhsArg = rhsTypeArguments[i];
if (!lhsArg.equals(rhsArg) &&
!(lhsArg instanceof WildcardType && isAssignable((WildcardType) lhsArg, rhsArg))) {
return false;
}
}
return true;
}
private static boolean isAssignable(WildcardType lhsType, Type rhsType) {
Type[] upperBounds = lhsType.getUpperBounds();
Type[] lowerBounds = lhsType.getLowerBounds();
for (int size = upperBounds.length, i = 0; i < size; ++i) {
if (!isAssignable(upperBounds[i], rhsType)) {
return false;
}
}
for (int size = lowerBounds.length, i = 0; i < size; ++i) {
if (!isAssignable(rhsType, lowerBounds[i])) {
return false;
}
}
return true;
}
}