| /* |
| * Copyright (C) 2011 The Guava Authors |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except |
| * in compliance with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software distributed under the License |
| * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express |
| * or implied. See the License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| |
| package com.google.common.base; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import com.google.common.annotations.Beta; |
| import com.google.common.annotations.GwtCompatible; |
| import java.io.Serializable; |
| import org.checkerframework.checker.nullness.qual.Nullable; |
| |
| /** |
| * Equivalence applied on functional result. |
| * |
| * @author Bob Lee |
| * @since 10.0 |
| */ |
| @Beta |
| @GwtCompatible |
| final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable { |
| |
| private static final long serialVersionUID = 0; |
| |
| private final Function<F, ? extends T> function; |
| private final Equivalence<T> resultEquivalence; |
| |
| FunctionalEquivalence(Function<F, ? extends T> function, Equivalence<T> resultEquivalence) { |
| this.function = checkNotNull(function); |
| this.resultEquivalence = checkNotNull(resultEquivalence); |
| } |
| |
| @Override |
| protected boolean doEquivalent(F a, F b) { |
| return resultEquivalence.equivalent(function.apply(a), function.apply(b)); |
| } |
| |
| @Override |
| protected int doHash(F a) { |
| return resultEquivalence.hash(function.apply(a)); |
| } |
| |
| @Override |
| public boolean equals(@Nullable Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (obj instanceof FunctionalEquivalence) { |
| FunctionalEquivalence<?, ?> that = (FunctionalEquivalence<?, ?>) obj; |
| return function.equals(that.function) && resultEquivalence.equals(that.resultEquivalence); |
| } |
| return false; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hashCode(function, resultEquivalence); |
| } |
| |
| @Override |
| public String toString() { |
| return resultEquivalence + ".onResultOf(" + function + ")"; |
| } |
| } |