core/src/main/java/org/jclouds/util/Optionals2.java

/*
 * 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.jclouds.util;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;

import com.google.common.base.Optional;
import com.google.common.reflect.Invokable;
import com.google.common.reflect.TypeToken;

public class Optionals2 {
   public static Class<?> unwrapIfOptional(TypeToken<?> type) {
      if (type.getRawType().isAssignableFrom(Optional.class)) {
         ParameterizedType futureType = ParameterizedType.class.cast(type.getType());
         // TODO: error checking in case this is a type, not a class.
         Type t = futureType.getActualTypeArguments()[0];
         if (t instanceof WildcardType) {
            t = ((WildcardType) t).getUpperBounds()[0];
         }
         return Class.class.cast(t);
      }
      return type.getRawType();
   }

   public static boolean isReturnTypeOptional(Invokable<?, ?> method) {
      return method.getReturnType().getRawType().isAssignableFrom(Optional.class);
   }
}