82 lines
2.1 KiB
Java
82 lines
2.1 KiB
Java
/*
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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 java.util.List;
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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 compares objects according to a given order. */
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@GwtCompatible(serializable = true)
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final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
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final ImmutableMap<T, Integer> rankMap;
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ExplicitOrdering(List<T> valuesInOrder) {
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this(buildRankMap(valuesInOrder));
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}
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ExplicitOrdering(ImmutableMap<T, Integer> rankMap) {
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this.rankMap = rankMap;
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}
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@Override
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public int compare(T left, T right) {
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return rank(left) - rank(right); // safe because both are nonnegative
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}
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private int rank(T value) {
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Integer rank = rankMap.get(value);
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if (rank == null) {
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throw new IncomparableValueException(value);
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}
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return rank;
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}
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private static <T> ImmutableMap<T, Integer> buildRankMap(List<T> valuesInOrder) {
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ImmutableMap.Builder<T, Integer> builder = ImmutableMap.builder();
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int rank = 0;
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for (T value : valuesInOrder) {
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builder.put(value, rank++);
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}
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return builder.build();
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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 ExplicitOrdering) {
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ExplicitOrdering<?> that = (ExplicitOrdering<?>) object;
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return this.rankMap.equals(that.rankMap);
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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 rankMap.hashCode();
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}
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@Override
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public String toString() {
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return "Ordering.explicit(" + rankMap.keySet() + ")";
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}
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private static final long serialVersionUID = 0;
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}
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