80 lines
2.1 KiB
Java
80 lines
2.1 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
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* use this file except in compliance with the License. You may obtain a copy
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* 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, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* 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.base;
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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.Beta;
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import com.google.common.annotations.GwtCompatible;
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/**
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* Equivalence applied on functional result.
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*
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* @author Bob Lee
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* @since 10.0
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*/
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@Beta
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@GwtCompatible
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final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable {
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private static final long serialVersionUID = 0;
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private final Function<F, ? extends T> function;
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private final Equivalence<T> resultEquivalence;
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FunctionalEquivalence(Function<F, ? extends T> function, Equivalence<T> resultEquivalence) {
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this.function = checkNotNull(function);
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this.resultEquivalence = checkNotNull(resultEquivalence);
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}
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@Override
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protected boolean doEquivalent(F a, F b) {
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return resultEquivalence.equivalent(function.apply(a), function.apply(b));
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}
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@Override
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protected int doHash(F a) {
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return resultEquivalence.hash(function.apply(a));
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}
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@Override
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public boolean equals(@Nullable Object obj) {
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if (obj == this) {
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return true;
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}
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if (obj instanceof FunctionalEquivalence) {
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FunctionalEquivalence<?, ?> that = (FunctionalEquivalence<?, ?>) obj;
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return function.equals(that.function) && resultEquivalence.equals(that.resultEquivalence);
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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, resultEquivalence);
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}
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@Override
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public String toString() {
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return resultEquivalence + ".onResultOf(" + function + ")";
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}
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}
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