core/src/main/java/org/jclouds/http/functions/UnwrapOnlyJsonValueInSet.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.http.functions;

import java.util.Set;

import javax.inject.Inject;
import javax.inject.Singleton;

import org.jclouds.http.HttpResponse;

import com.google.common.base.Function;
import com.google.common.collect.Iterables;

@Singleton
public class UnwrapOnlyJsonValueInSet<T> implements Function<HttpResponse, T> {

   private final UnwrapOnlyJsonValue<Set<T>> json;

   @Inject
   UnwrapOnlyJsonValueInSet(UnwrapOnlyJsonValue<Set<T>> json) {
      this.json = json;
   }

   @Override
   public T apply(HttpResponse arg0) {
      Set<T> set = json.apply(arg0);
      if (set == null || set.isEmpty())
         return null;
      return Iterables.getOnlyElement(set);
   }
}