| /* |
| * Copyright 2000-2009 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.openapi.util; |
| |
| import com.intellij.util.NullableFunction; |
| import com.intellij.util.ObjectUtils; |
| import org.jetbrains.annotations.NonNls; |
| import org.jetbrains.annotations.Nullable; |
| |
| /** |
| * @author peter |
| */ |
| public class NullableLazyKey<T,H extends UserDataHolder> extends Key<T>{ |
| private final NullableFunction<H,T> myFunction; |
| |
| private NullableLazyKey(@NonNls String name, final NullableFunction<H, T> function) { |
| super(name); |
| myFunction = function; |
| } |
| |
| @Nullable |
| public final T getValue(H h) { |
| T data = h.getUserData(this); |
| if (data == null) { |
| data = myFunction.fun(h); |
| h.putUserData(this, data == null ? (T)ObjectUtils.NULL : data); |
| } |
| return data == ObjectUtils.NULL ? null : data; |
| } |
| |
| public static <T,H extends UserDataHolder> NullableLazyKey<T,H> create(@NonNls String name, final NullableFunction<H, T> function) { |
| return new NullableLazyKey<T,H>(name, function); |
| } |
| } |