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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 android.support.annotation.Nullable;
import java.util.concurrent.Executor;
abstract class ContiguousDataSource<Key, Value> extends DataSource<Key, Value> {
@Override
boolean isContiguous() {
return true;
}
abstract void loadInitial(@Nullable Key key, int initialLoadSize,
int pageSize, boolean enablePlaceholders,
@NonNull Executor mainThreadExecutor, @NonNull PageResult.Receiver<Value> receiver);
abstract void loadAfter(int currentEndIndex, @NonNull Value currentEndItem, int pageSize,
@NonNull Executor mainThreadExecutor, @NonNull PageResult.Receiver<Value> receiver);
abstract void loadBefore(int currentBeginIndex, @NonNull Value currentBeginItem, int pageSize,
@NonNull Executor mainThreadExecutor, @NonNull PageResult.Receiver<Value> receiver);
/**
* Get the key from either the position, or item, or null if position/item invalid.
* <p>
* Position may not match passed item's position - if trying to query the key from a position
* that isn't yet loaded, a fallback item (last loaded item accessed) will be passed.
*/
abstract Key getKey(int position, Value item);
}
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