core/src/main/java/org/jclouds/rest/functions/ReturnEmptyPagedIterableOnNotFoundOr404.java

/**
 * Licensed to jclouds, Inc. (jclouds) under one or more
 * contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  jclouds 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.rest.functions;

import static com.google.common.base.Preconditions.checkNotNull;

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

import org.jclouds.collect.PagedIterables;
import org.jclouds.http.functions.ReturnTrueOn404;
import org.jclouds.rest.ResourceNotFoundException;

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

/**
 * 
 * @author Adrian Cole
 */
@Singleton
public class ReturnEmptyPagedIterableOnNotFoundOr404 implements Function<Exception, Object> {
   private final ReturnTrueOn404 rto404;

   @Inject
   private ReturnEmptyPagedIterableOnNotFoundOr404(ReturnTrueOn404 rto404) {
      this.rto404 = checkNotNull(rto404, "rto404");
   }

   public Object apply(Exception from) {
      Iterable<ResourceNotFoundException> throwables = Iterables.filter(Throwables.getCausalChain(from),
               ResourceNotFoundException.class);
      if (Iterables.size(throwables) >= 1) {
         return PagedIterables.EMPTY;
      } else if (rto404.apply(from)) {
         return PagedIterables.EMPTY;
      }
      throw Throwables.propagate(from);
   }

}