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/*
* Copyright 2000-2016 Vaadin Ltd.
*
* 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.vaadin.data.provider;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.stream.Stream;
import com.vaadin.server.SerializableFunction;
import com.vaadin.server.SerializableToIntFunction;
import com.vaadin.shared.Registration;
/**
* A {@link DataProvider} for any back end.
*
* @param <T>
* data provider data type
* @param <F>
* data provider filter type
*/
public class BackEndDataProvider<T, F> extends AbstractDataProvider<T, F> {
private final SerializableFunction<Query<T, F>, Stream<T>> request;
private final SerializableToIntFunction<Query<T, F>> sizeCallback;
/**
* Constructs a new DataProvider to request data from an arbitrary back end
* request function.
*
* @param request
* function that requests data from back end based on query
* @param sizeCallback
* function that return the amount of data in back end for query
*/
public BackEndDataProvider(
SerializableFunction<Query<T, F>, Stream<T>> request,
SerializableToIntFunction<Query<T, F>> sizeCallback) {
Objects.requireNonNull(request, "Request function can't be null");
Objects.requireNonNull(sizeCallback, "Size callback can't be null");
this.request = request;
this.sizeCallback = sizeCallback;
}
@Override
public Stream<T> fetch(Query<T, F> query) {
return request.apply(query);
}
@Override
public int size(Query<T, F> query) {
return sizeCallback.applyAsInt(query);
}
/**
* Sets a default sorting order to the data provider.
*
* @param sortOrders
* a list of sorting information containing field ids and
* directions
* @return new data provider with modified sorting
*/
@SuppressWarnings("serial")
public BackEndDataProvider<T, F> sortingBy(
List<SortOrder<String>> sortOrders) {
BackEndDataProvider<T, F> parent = this;
return new BackEndDataProvider<T, F>(query -> {
List<SortOrder<String>> queryOrder = new ArrayList<>(
query.getSortOrders());
queryOrder.addAll(sortOrders);
return parent.fetch(new Query<>(query.getOffset(), query.getLimit(),
queryOrder, query.getInMemorySorting(),
query.getFilter().orElse(null)));
}, sizeCallback) {
@Override
public Registration addDataProviderListener(
DataProviderListener listener) {
return parent.addDataProviderListener(listener);
}
@Override
public void refreshAll() {
parent.refreshAll();
}
};
}
@Override
public boolean isInMemory() {
return false;
}
}
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