89 lines
2.2 KiB
Java
89 lines
2.2 KiB
Java
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/*
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* Copyright (C) 2007 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* 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
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under 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 javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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/** An ordering that treats {@code null} as greater than all other values. */
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@GwtCompatible(serializable = true)
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final class NullsLastOrdering<T> extends Ordering<T> implements Serializable {
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final Ordering<? super T> ordering;
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NullsLastOrdering(Ordering<? super T> ordering) {
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this.ordering = ordering;
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}
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@Override
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public int compare(@Nullable T left, @Nullable T right) {
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if (left == right) {
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return 0;
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}
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if (left == null) {
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return LEFT_IS_GREATER;
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}
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if (right == null) {
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return RIGHT_IS_GREATER;
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}
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return ordering.compare(left, right);
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}
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@Override
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public <S extends T> Ordering<S> reverse() {
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// ordering.reverse() might be optimized, so let it do its thing
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return ordering.reverse().nullsFirst();
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}
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@Override
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public <S extends T> Ordering<S> nullsFirst() {
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return ordering.nullsFirst();
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}
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@SuppressWarnings("unchecked") // still need the right way to explain this
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@Override
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public <S extends T> Ordering<S> nullsLast() {
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return (Ordering<S>) this;
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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 == this) {
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return true;
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}
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if (object instanceof NullsLastOrdering) {
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NullsLastOrdering<?> that = (NullsLastOrdering<?>) object;
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return this.ordering.equals(that.ordering);
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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 ordering.hashCode() ^ -921210296; // meaningless
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}
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@Override
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public String toString() {
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return ordering + ".nullsLast()";
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}
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private static final long serialVersionUID = 0;
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}
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