| /** |
| * Copyright (C) 2008 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 com.google.inject.internal; |
| |
| import com.google.inject.internal.util.Function; |
| import com.google.inject.internal.util.MapMaker; |
| import com.google.inject.internal.util.Nullable; |
| |
| import java.util.Map; |
| |
| /** |
| * Lazily creates (and caches) values for keys. If creating the value fails (with errors), an |
| * exception is thrown on retrieval. |
| * |
| * @author jessewilson@google.com (Jesse Wilson) |
| */ |
| public abstract class FailableCache<K, V> { |
| |
| private final Map<K, Object> delegate = new MapMaker().makeComputingMap( |
| new Function<K, Object>() { |
| public Object apply(@Nullable K key) { |
| Errors errors = new Errors(); |
| V result = null; |
| try { |
| result = FailableCache.this.create(key, errors); |
| } catch (ErrorsException e) { |
| errors.merge(e.getErrors()); |
| } |
| return errors.hasErrors() ? errors : result; |
| } |
| }); |
| |
| protected abstract V create(K key, Errors errors) throws ErrorsException; |
| |
| public V get(K key, Errors errors) throws ErrorsException { |
| Object resultOrError = delegate.get(key); |
| if (resultOrError instanceof Errors) { |
| errors.merge((Errors) resultOrError); |
| throw errors.toException(); |
| } else { |
| @SuppressWarnings("unchecked") // create returned a non-error result, so this is safe |
| V result = (V) resultOrError; |
| return result; |
| } |
| } |
| |
| boolean remove(K key) { |
| return delegate.remove(key) != null; |
| } |
| } |