/**
* (c) Copyright 2014 WibiData, Inc.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*
* 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 org.kiji.schema.impl;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSortedMap;
import com.google.common.collect.Iterators;
import org.kiji.annotations.ApiAudience;
import org.kiji.schema.KijiCell;
import org.kiji.schema.KijiColumnName;
import org.kiji.schema.KijiDataRequest;
import org.kiji.schema.KijiDataRequest.Column;
import org.kiji.schema.KijiDataRequestBuilder;
import org.kiji.schema.KijiDataRequestBuilder.ColumnsDef;
import org.kiji.schema.KijiPager;
import org.kiji.schema.KijiResult;
import org.kiji.schema.KijiRowData;
import org.kiji.schema.layout.KijiTableLayout;
/**
* A Kiji pager backed by a {@link KijiResult}.
*/
@ApiAudience.Private
public class KijiResultPager implements KijiPager {
private final KijiResult<Object> mResult;
private final Iterator<KijiCell<Object>> mCells;
private final Column mColumnRequest;
private final KijiTableLayout mLayout;
/**
* Create a Kiji pager backed by a {@code KijiResult}.
*
* @param result The {@code KijiResult} backing this pager.
* @param layout The {@code KijiTableLayout} of the table.
*/
public KijiResultPager(
final KijiResult<Object> result,
final KijiTableLayout layout
) {
mResult = result;
mCells = mResult.iterator();
mLayout = layout;
final KijiDataRequest dataRequest = mResult.getDataRequest();
final Collection<Column> columnRequests = dataRequest.getColumns();
Preconditions.checkArgument(columnRequests.size() == 1,
"Can not create KijiResultPager with multiple columns. Data request: %s.", dataRequest);
mColumnRequest = columnRequests.iterator().next();
}
/** {@inheritDoc} */
@Override
public KijiRowData next() {
return next(mColumnRequest.getPageSize());
}
/** {@inheritDoc} */
@Override
public KijiRowData next(final int pageSize) {
if (!hasNext()) {
throw new NoSuchElementException("Kiji pager is exhausted.");
}
final KijiColumnName column = mColumnRequest.getColumnName();
final ColumnsDef columnDef = ColumnsDef
.create()
.withFilter(mColumnRequest.getFilter())
.withPageSize(KijiDataRequest.PAGING_DISABLED)
.withMaxVersions(mColumnRequest.getMaxVersions())
.add(column, mColumnRequest.getReaderSpec());
final KijiDataRequestBuilder dataRequest = KijiDataRequest.builder();
dataRequest.addColumns(columnDef);
final List<KijiCell<Object>> cells =
ImmutableList.copyOf(Iterators.limit(mCells, pageSize));
final KijiResult<Object> result = MaterializedKijiResult.create(
mResult.getEntityId(),
dataRequest.build(),
mLayout,
ImmutableSortedMap.<KijiColumnName, List<KijiCell<Object>>>naturalOrder()
.put(column, cells)
.build());
return new KijiResultRowData(mLayout, result);
}
/** {@inheritDoc} */
@Override
public void remove() {
throw new UnsupportedOperationException("KijiPager does not support remove.");
}
/** {@inheritDoc} */
@Override
public void close() throws IOException {
mResult.close();
}
/** {@inheritDoc} */
@Override
public boolean hasNext() {
return mCells.hasNext();
}
}