1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.lang3.function;
19
20 import java.util.function.Function;
21
22 /**
23 * Factory for {@link Function}.
24 *
25 * @since 3.14.0
26 */
27 public final class Functions {
28
29 /**
30 * Applies the {@link Function} on the object if the function is not {@code null}. Otherwise, does nothing and returns {@code null}.
31 *
32 * @param function the function to apply.
33 * @param object the object to apply the function.
34 * @param <T> the type of the argument the function applies.
35 * @param <R> the type of the result the function returns.
36 * @return the value the function returns if the function is not {@code null}; {@code null} otherwise.
37 * @since 3.15.0
38 */
39 public static <T, R> R apply(final Function<T, R> function, final T object) {
40 return function != null ? function.apply(object) : null;
41 }
42
43 /**
44 * Starts a fluent chain like {@code function(foo::bar).andThen(...).andThen(...).apply(...);}
45 *
46 * @param <T> Input type.
47 * @param <R> Return type.
48 * @param function the argument to return.
49 * @return the argument
50 */
51 public static <T, R> Function<T, R> function(final Function<T, R> function) {
52 return function;
53 }
54
55 private Functions() {
56 // no instances needed.
57 }
58 }