/*
    * Copyright (C) 2011 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;
  
  import com.google.common.annotations.GwtCompatible;
  import com.google.common.annotations.GwtIncompatible;
  
  import java.io.Serializable;
  import java.util.NoSuchElementException;
  import java.util.Set;
  
  import javax.annotation.Nullable;
  
  /**
   * An empty contiguous set.
   *
   * @author Gregory Kick
   */
  @GwtCompatible(emulated = true)
  @SuppressWarnings("unchecked") // allow ungenerified Comparable types
  final class EmptyContiguousSet<C extends Comparable> extends ContiguousSet<C> {
    EmptyContiguousSet(DiscreteDomain<C> domain) {
      super(domain);
    }
  
    @Override public C first() {
      throw new NoSuchElementException();
    }
  
    @Override public C last() {
      throw new NoSuchElementException();
    }
  
    @Override public int size() {
      return 0;
    }
  
    @Override public ContiguousSet<C> intersection(ContiguousSet<C> other) {
      return this;
    }
  
    @Override public Range<C> range() {
      throw new NoSuchElementException();
    }
  
    @Override public Range<C> range(BoundType lowerBoundType, BoundType upperBoundType) {
      throw new NoSuchElementException();
    }
  
    @Override ContiguousSet<C> headSetImpl(C toElement, boolean inclusive) {
      return this;
    }
  
    @Override ContiguousSet<C> subSetImpl(
        C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
      return this;
    }
  
    @Override ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {
      return this;
    }
  
    @GwtIncompatible("not used by GWT emulation")
    @Override int indexOf(Object target) {
      return -1;
    }
  
    @Override public UnmodifiableIterator<C> iterator() {
      return Iterators.emptyIterator();
    }
  
    @GwtIncompatible("NavigableSet")
    @Override public UnmodifiableIterator<C> descendingIterator() {
      return Iterators.emptyIterator();
    }
  
    @Override boolean isPartialView() {
      return false;
    }
  
    @Override public boolean isEmpty() {
      return true;
    }
  
    @Override public ImmutableList<C> asList() {
      return ImmutableList.of();
    }
  
   @Override public String toString() {
     return "[]";
   }
 
   @Override public boolean equals(@Nullable Object object) {
     if (object instanceof Set) {
       Set<?> that = (Set<?>) object;
       return that.isEmpty();
     }
     return false;
   }
 
   @Override public int hashCode() {
     return 0;
   }
 
   @GwtIncompatible("serialization")
   private static final class SerializedForm<C extends Comparable> implements Serializable {
     private final DiscreteDomain<C> domain;
 
     private SerializedForm(DiscreteDomain<C> domain) {
       this.domain = domain;
     }
 
     private Object readResolve() {
       return new EmptyContiguousSet<C>(domain);
     }
 
     private static final long serialVersionUID = 0;
   }
 
   @GwtIncompatible("serialization")
   @Override
   Object writeReplace() {
     return new SerializedForm<C>(domain);
   }
 
   @GwtIncompatible("NavigableSet")
   ImmutableSortedSet<C> createDescendingSet() {
     return new EmptyImmutableSortedSet<C>(Ordering.natural().reverse());
   }
 }