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/*
* Copyright (C) 2017 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 android.arch.paging;
import android.support.annotation.NonNull;
import java.util.ArrayList;
import java.util.List;
class ListDataSource<T> extends PositionalDataSource<T> {
private final List<T> mList;
public ListDataSource(List<T> list) {
mList = new ArrayList<>(list);
}
@Override
public void loadInitial(int requestedStartPosition, int requestedLoadSize, int pageSize,
@NonNull InitialLoadCallback<T> callback) {
final int totalCount = mList.size();
final int firstLoadPosition = computeFirstLoadPosition(
requestedStartPosition, requestedLoadSize, pageSize, totalCount);
final int firstLoadSize = Math.min(totalCount - firstLoadPosition, requestedLoadSize);
// for simplicity, we could return everything immediately,
// but we tile here since it's expected behavior
List<T> sublist = mList.subList(firstLoadPosition, firstLoadPosition + firstLoadSize);
callback.onResult(sublist, firstLoadPosition, totalCount);
}
@Override
public void loadRange(int startPosition, int count, @NonNull LoadCallback<T> callback) {
callback.onResult(mList.subList(startPosition, startPosition + count));
}
}
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