/*
* Copyright 2014, Stratio.
*
* 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.stratio.cassandra.index;
import com.stratio.cassandra.index.query.Sorting;
import com.stratio.cassandra.index.query.SortingField;
import com.stratio.cassandra.index.schema.Columns;
import com.stratio.cassandra.index.schema.Schema;
import com.stratio.cassandra.index.util.ComparatorChain;
import org.apache.cassandra.db.Row;
import java.util.Comparator;
/**
* A {@link Comparator} for comparing {@link Row}s according to a certain {@link Sorting}.
*
* @author Andres de la Pena <adelapena@stratio.com>
*/
public class RowComparatorSorting implements RowComparator
{
private final RowMapper rowMapper;
private final ComparatorChain<Columns> comparatorChain;
/**
* @param rowMapper The indexing {@link Schema} of the {@link Row}s to be compared.
* @param sorting The {@link Sorting} inf which the {@link Row} comparison is based.
*/
public RowComparatorSorting(RowMapper rowMapper, Sorting sorting)
{
this.rowMapper = rowMapper;
comparatorChain = new ComparatorChain<>();
for (SortingField sortingField : sorting.getSortingFields())
{
Comparator<Columns> comparator = sortingField.comparator();
comparatorChain.addComparator(comparator);
}
}
/**
* {@inheritDoc}
*
* @param row1 A {@link Row}.
* @param row2 A {@link Row}.
* @return A negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater
* than the second according to a {@link Sorting}.
*/
@Override
public int compare(Row row1, Row row2)
{
Columns columns1 = rowMapper.columns(row1);
Columns columns2 = rowMapper.columns(row2);
return comparatorChain.compare(columns1, columns2);
}
}