72 lines
2.0 KiB
Java
72 lines
2.0 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 static com.google.common.base.Preconditions.checkNotNull;
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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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import com.google.common.base.Function;
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import com.google.common.base.Objects;
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/**
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* An ordering that orders elements by applying an order to the result of a
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* function on those elements.
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*/
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@GwtCompatible(serializable = true)
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final class ByFunctionOrdering<F, T> extends Ordering<F> implements Serializable {
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final Function<F, ? extends T> function;
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final Ordering<T> ordering;
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ByFunctionOrdering(Function<F, ? extends T> function, Ordering<T> ordering) {
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this.function = checkNotNull(function);
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this.ordering = checkNotNull(ordering);
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}
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@Override
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public int compare(F left, F right) {
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return ordering.compare(function.apply(left), function.apply(right));
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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 ByFunctionOrdering) {
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ByFunctionOrdering<?, ?> that = (ByFunctionOrdering<?, ?>) object;
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return this.function.equals(that.function) && 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 Objects.hashCode(function, ordering);
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}
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@Override
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public String toString() {
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return ordering + ".onResultOf(" + function + ")";
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}
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private static final long serialVersionUID = 0;
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}
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