/*
 * 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 org.checkerframework.checker.nullness.qual.Nullable;

An empty contiguous set.
Author:Gregory Kick
/** * 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; } @Override public boolean contains(Object object) { return false; } @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; } @GwtIncompatible // not used in GWT @Override boolean isHashCodeFast() { return true; } @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 ImmutableSortedSet.emptySet(Ordering.natural().reverse()); } }