| /* |
| * Copyright 2018 The Android Open Source Project |
| * |
| * 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 androidx.paging; |
| |
| import androidx.annotation.NonNull; |
| import androidx.arch.core.util.Function; |
| |
| import java.util.IdentityHashMap; |
| import java.util.List; |
| |
| class WrapperItemKeyedDataSource<K, A, B> extends ItemKeyedDataSource<K, B> { |
| private final ItemKeyedDataSource<K, A> mSource; |
| private final Function<List<A>, List<B>> mListFunction; |
| |
| private final IdentityHashMap<B, K> mKeyMap = new IdentityHashMap<>(); |
| |
| WrapperItemKeyedDataSource(ItemKeyedDataSource<K, A> source, |
| Function<List<A>, List<B>> listFunction) { |
| mSource = source; |
| mListFunction = listFunction; |
| } |
| |
| @Override |
| public void addInvalidatedCallback(@NonNull InvalidatedCallback onInvalidatedCallback) { |
| mSource.addInvalidatedCallback(onInvalidatedCallback); |
| } |
| |
| @Override |
| public void removeInvalidatedCallback(@NonNull InvalidatedCallback onInvalidatedCallback) { |
| mSource.removeInvalidatedCallback(onInvalidatedCallback); |
| } |
| |
| @Override |
| public void invalidate() { |
| mSource.invalidate(); |
| } |
| |
| @Override |
| public boolean isInvalid() { |
| return mSource.isInvalid(); |
| } |
| |
| private List<B> convertWithStashedKeys(List<A> source) { |
| List<B> dest = convert(mListFunction, source); |
| synchronized (mKeyMap) { |
| // synchronize on mKeyMap, since multiple loads may occur simultaneously. |
| // Note: manually sync avoids locking per-item (e.g. Collections.synchronizedMap) |
| for (int i = 0; i < dest.size(); i++) { |
| mKeyMap.put(dest.get(i), mSource.getKey(source.get(i))); |
| } |
| } |
| return dest; |
| } |
| |
| @Override |
| public void loadInitial(@NonNull LoadInitialParams<K> params, |
| final @NonNull LoadInitialCallback<B> callback) { |
| mSource.loadInitial(params, new LoadInitialCallback<A>() { |
| @Override |
| public void onResult(@NonNull List<A> data, int position, int totalCount) { |
| callback.onResult(convertWithStashedKeys(data), position, totalCount); |
| } |
| |
| @Override |
| public void onResult(@NonNull List<A> data) { |
| callback.onResult(convertWithStashedKeys(data)); |
| } |
| }); |
| } |
| |
| @Override |
| public void loadAfter(@NonNull LoadParams<K> params, |
| final @NonNull LoadCallback<B> callback) { |
| mSource.loadAfter(params, new LoadCallback<A>() { |
| @Override |
| public void onResult(@NonNull List<A> data) { |
| callback.onResult(convertWithStashedKeys(data)); |
| } |
| }); |
| } |
| |
| @Override |
| public void loadBefore(@NonNull LoadParams<K> params, |
| final @NonNull LoadCallback<B> callback) { |
| mSource.loadBefore(params, new LoadCallback<A>() { |
| @Override |
| public void onResult(@NonNull List<A> data) { |
| callback.onResult(convertWithStashedKeys(data)); |
| } |
| }); |
| } |
| |
| @NonNull |
| @Override |
| public K getKey(@NonNull B item) { |
| synchronized (mKeyMap) { |
| return mKeyMap.get(item); |
| } |
| } |
| } |