/*
    * Copyright (C) 2013 The Guava 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 com.google.common.collect.testing.google;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.collect.Multiset;
  import com.google.common.collect.testing.features.Feature;
  import com.google.common.collect.testing.features.TesterAnnotation;
  
  import java.lang.annotation.Inherited;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.util.Collections;
  import java.util.Set;
  
  /**
   * Optional features of classes derived from {@link Multiset}.
   *
   * @author Louis Wasserman
   */
  @GwtCompatible
  public enum MultisetFeature implements Feature<Multiset> {
    /**
     * Indicates that elements from {@code Multiset.entrySet()} update to reflect changes in the
     * backing multiset.
     */
    ENTRIES_ARE_VIEWS;
  
    @Override
    public Set<Feature<? super Multiset>> getImpliedFeatures() {
      return Collections.emptySet();
    }
  
    @Retention(RetentionPolicy.RUNTIME)
    @Inherited
    @TesterAnnotation
    public @interface Require {
      public abstract MultisetFeature[] value() default {};
      public abstract MultisetFeature[] absent() default {};
    }
  }