| /* |
| * Copyright 2000-2014 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.Nullable; |
| |
| import java.util.Collection; |
| |
| /** |
| * @author max |
| * @author Konstantin Bulenkov |
| */ |
| @SuppressWarnings({"unchecked"}) |
| public interface Function<Param, Result> { |
| Result fun(Param param); |
| |
| Function ID = new Function() { |
| public Object fun(final Object o) { |
| return o; |
| } |
| }; |
| |
| Function NULL = NullableFunction.NULL; |
| |
| Function TO_STRING = new Function() { |
| public Object fun(Object o) { |
| return String.valueOf(o); |
| } |
| }; |
| |
| final class Self<P, R> implements Function<P, R> { |
| public R fun(P p) { |
| return (R)p; |
| } |
| } |
| |
| interface Mono<T> extends Function<T, T> {} |
| |
| final class InstanceOf<P, R extends P> implements NullableFunction<P, R> { |
| |
| private final Class<R> myResultClass; |
| |
| public InstanceOf(Class<R> resultClass) { |
| myResultClass = resultClass; |
| } |
| |
| @Nullable |
| public R fun(P p) { |
| return p.getClass().isAssignableFrom(myResultClass) ? (R)p : null; |
| } |
| } |
| |
| final class First<P, R extends P> implements Function<P[], R> { |
| public R fun(P[] ps) { |
| return (R)ps[0]; |
| } |
| } |
| |
| final class FirstInCollection<P, R extends P> implements Function<Collection<P>, R> { |
| public R fun(Collection<P> ps) { |
| return (R)ps.iterator().next(); |
| } |
| } |
| |
| class Predefined { |
| public static <I,O> Function<I, O> NULL() { |
| return NULL; |
| } |
| public static <I,O> Function<I, O> TO_STRING() { |
| return TO_STRING; |
| } |
| } |
| } |