juzu.impl.common.Introspector Maven / Gradle / Ivy
/*
* Copyright 2013 eXo Platform SAS
*
* 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 juzu.impl.common;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.List;
/** @author Julien Viet */
public class Introspector {
public static Class resolveToClass(Type implementation, Class type, int parameterIndex) {
if (implementation == null) {
throw new NullPointerException("No null type accepted");
}
// First resolve to type
Type resolvedType = resolve(implementation, type, parameterIndex);
//
if (resolvedType != null) {
return resolveToClass(resolvedType);
} else {
return null;
}
}
public static Class resolveToClass(Type type) {
if (type == null) {
throw new NullPointerException("No null type accepted");
}
if (type instanceof Class) {
return (Class)type;
} else if (type instanceof TypeVariable) {
TypeVariable resolvedTypeVariable = (TypeVariable)type;
return resolveToClass(resolvedTypeVariable.getBounds()[0]);
} else {
throw new UnsupportedOperationException("Type resolution of " + type + " not yet implemented");
}
}
/**
* A simplistic implementation, it may not handle all cases but it should handle enough.
*
* @param implementation the type for which the parameter requires a resolution
* @param type the type that owns the parameter
* @param parameterIndex the parameter index
* @return the resolved type
*/
public static Type resolve(Type implementation, Class type, int parameterIndex) {
if (implementation == null) {
throw new NullPointerException();
}
//
if (implementation == type) {
TypeVariable>[] tp = type.getTypeParameters();
if (parameterIndex < tp.length) {
return tp[parameterIndex];
} else {
throw new IllegalArgumentException();
}
} else if (implementation instanceof Class) {
Class c = (Class) implementation;
Type gsc = c.getGenericSuperclass();
Type resolved = null;
if (gsc != null) {
resolved = resolve(gsc, type, parameterIndex);
if (resolved == null) {
// Try with interface
}
}
return resolved;
} else if (implementation instanceof ParameterizedType) {
ParameterizedType pt = (ParameterizedType) implementation;
Type[] typeArgs = pt.getActualTypeArguments();
Type rawType = pt.getRawType();
if (rawType == type) {
return typeArgs[parameterIndex];
} else if (rawType instanceof Class) {
Class classRawType = (Class)rawType;
Type resolved = resolve(classRawType, type, parameterIndex);
if (resolved == null) {
return null;
} else if (resolved instanceof TypeVariable) {
TypeVariable resolvedTV = (TypeVariable)resolved;
TypeVariable[] a = classRawType.getTypeParameters();
for (int i = 0;i < a.length;i++) {
if (a[i].equals(resolvedTV)) {
return resolve(implementation, classRawType, i);
}
}
throw new AssertionError();
} else {
throw new UnsupportedOperationException("Cannot support resolution of " + resolved);
}
} else {
throw new UnsupportedOperationException();
}
} else {
throw new UnsupportedOperationException("todo " + implementation + " " + implementation.getClass());
}
}
public static boolean instanceOf(Class c, List types) {
for (String type: types) {
if (instanceOf(c, type)) {
return true;
}
}
return false;
}
public static boolean instanceOf(Class c, String type) {
if (c.getName().equals(type)) {
return true;
}
for (Class i : c.getInterfaces()) {
if (instanceOf(i, type)) {
return true;
}
}
if (c.getSuperclass() != null) {
return instanceOf(c.getSuperclass(), type);
}
return false;
}
}