159 lines
3.4 KiB
Java
159 lines
3.4 KiB
Java
/*
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* Copyright (C) 2011 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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* in compliance with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package com.google.common.collect;
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import java.io.Serializable;
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import java.util.NoSuchElementException;
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import java.util.Set;
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import javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.annotations.GwtIncompatible;
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/**
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* An empty contiguous set.
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*
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* @author Gregory Kick
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*/
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@GwtCompatible(emulated = true)
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@SuppressWarnings("unchecked") // allow ungenerified Comparable types
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final class EmptyContiguousSet<C extends Comparable> extends ContiguousSet<C> {
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EmptyContiguousSet(DiscreteDomain<C> domain) {
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super(domain);
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}
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@Override
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public C first() {
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throw new NoSuchElementException();
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}
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@Override
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public C last() {
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throw new NoSuchElementException();
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}
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@Override
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public int size() {
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return 0;
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}
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@Override
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public ContiguousSet<C> intersection(ContiguousSet<C> other) {
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return this;
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}
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@Override
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public Range<C> range() {
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throw new NoSuchElementException();
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}
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@Override
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public Range<C> range(BoundType lowerBoundType, BoundType upperBoundType) {
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throw new NoSuchElementException();
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}
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@Override
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ContiguousSet<C> headSetImpl(C toElement, boolean inclusive) {
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return this;
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}
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@Override
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ContiguousSet<C> subSetImpl(C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
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return this;
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}
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@Override
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ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {
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return this;
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}
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@GwtIncompatible("not used by GWT emulation")
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@Override
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int indexOf(Object target) {
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return -1;
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}
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@Override
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public UnmodifiableIterator<C> iterator() {
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return Iterators.emptyIterator();
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}
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@GwtIncompatible("NavigableSet")
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@Override
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public UnmodifiableIterator<C> descendingIterator() {
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return Iterators.emptyIterator();
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}
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@Override
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boolean isPartialView() {
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return false;
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}
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@Override
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public boolean isEmpty() {
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return true;
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}
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@Override
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public ImmutableList<C> asList() {
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return ImmutableList.of();
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}
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@Override
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public String toString() {
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return "[]";
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}
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@Override
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public boolean equals(@Nullable Object object) {
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if (object instanceof Set) {
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Set<?> that = (Set<?>) object;
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return that.isEmpty();
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}
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return false;
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}
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@Override
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public int hashCode() {
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return 0;
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}
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@GwtIncompatible("serialization")
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private static final class SerializedForm<C extends Comparable> implements Serializable {
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private final DiscreteDomain<C> domain;
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private SerializedForm(DiscreteDomain<C> domain) {
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this.domain = domain;
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}
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private Object readResolve() {
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return new EmptyContiguousSet<C>(domain);
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}
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private static final long serialVersionUID = 0;
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}
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@GwtIncompatible("serialization")
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@Override
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Object writeReplace() {
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return new SerializedForm<C>(domain);
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}
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@GwtIncompatible("NavigableSet")
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ImmutableSortedSet<C> createDescendingSet() {
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return new EmptyImmutableSortedSet<C>(Ordering.natural().reverse());
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}
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}
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