| /* |
| * Copyright 2000-2012 JetBrains s.r.o. |
| * |
| * 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.intellij.util; |
| |
| import org.jetbrains.annotations.NotNull; |
| |
| /** |
| * @author nik |
| */ |
| public class FunctionUtil { |
| private FunctionUtil() { } |
| |
| @NotNull |
| public static <T> Function<T, T> id() { |
| @SuppressWarnings("unchecked") Function<T, T> id = Function.ID; |
| return id; |
| } |
| |
| @NotNull |
| public static <A, B> NullableFunction<A, B> nullConstant() { |
| @SuppressWarnings("unchecked") NullableFunction<A, B> function = NullableFunction.NULL; |
| return function; |
| } |
| |
| @NotNull |
| public static <T> Function<T, String> string() { |
| @SuppressWarnings("unchecked") Function<T, String> function = Function.TO_STRING; |
| return function; |
| } |
| |
| @NotNull |
| public static <A, B> Function<A, B> constant(final B b) { |
| return new Function<A, B>() { |
| @Override |
| public B fun(A a) { |
| return b; |
| } |
| }; |
| } |
| |
| @NotNull |
| public static <A, B, C> NotNullFunction<A, C> composition(@NotNull final NotNullFunction<B, C> f, @NotNull final NotNullFunction<A, B> g) { |
| return new NotNullFunction<A, C>() { |
| @Override |
| @NotNull |
| public C fun(A a) { |
| return f.fun(g.fun(a)); |
| } |
| }; |
| } |
| } |