| /* |
| * Copyright (C) 2007 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.collect; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import com.google.common.annotations.GwtCompatible; |
| import com.google.common.base.Function; |
| import com.google.common.base.Objects; |
| import java.io.Serializable; |
| import org.checkerframework.checker.nullness.compatqual.NullableDecl; |
| |
| /** |
| * An ordering that orders elements by applying an order to the result of a function on those |
| * elements. |
| */ |
| @GwtCompatible(serializable = true) |
| final class ByFunctionOrdering<F, T> extends Ordering<F> implements Serializable { |
| final Function<F, ? extends T> function; |
| final Ordering<T> ordering; |
| |
| ByFunctionOrdering(Function<F, ? extends T> function, Ordering<T> ordering) { |
| this.function = checkNotNull(function); |
| this.ordering = checkNotNull(ordering); |
| } |
| |
| @Override |
| public int compare(F left, F right) { |
| return ordering.compare(function.apply(left), function.apply(right)); |
| } |
| |
| @Override |
| public boolean equals(@NullableDecl Object object) { |
| if (object == this) { |
| return true; |
| } |
| if (object instanceof ByFunctionOrdering) { |
| ByFunctionOrdering<?, ?> that = (ByFunctionOrdering<?, ?>) object; |
| return this.function.equals(that.function) && this.ordering.equals(that.ordering); |
| } |
| return false; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hashCode(function, ordering); |
| } |
| |
| @Override |
| public String toString() { |
| return ordering + ".onResultOf(" + function + ")"; |
| } |
| |
| private static final long serialVersionUID = 0; |
| } |