| /* |
| * Copyright 2015 Google Inc. |
| * |
| * 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 java.util.function; |
| |
| import static javaemul.internal.InternalPreconditions.checkCriticalNotNull; |
| |
| /** |
| * See <a href="https://docs.oracle.com/javase/8/docs/api/java/util/function/Function.html"> |
| * the official Java API doc</a> for details. |
| * |
| * @param <T> type of the argument |
| * @param <R> type of the return value |
| */ |
| @FunctionalInterface |
| public interface Function<T, R> { |
| |
| static <T> Function<T, T> identity() { |
| return t -> t; |
| } |
| |
| R apply(T t); |
| |
| default <V> Function<T, V> andThen(Function<? super R, ? extends V> after) { |
| checkCriticalNotNull(after); |
| return t -> after.apply(apply(t)); |
| } |
| |
| default <V> Function<V, R> compose(Function<? super V, ? extends T> before) { |
| checkCriticalNotNull(before); |
| return t -> apply(before.apply(t)); |
| } |
| } |