/*
* 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.facebook.presto.tuple;
import com.facebook.presto.operator.SortOrder;
import com.google.common.collect.ImmutableList;
import java.util.Comparator;
import java.util.List;
import static com.facebook.presto.tuple.TupleInfo.Type;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* Compares two rows element by element.
*/
public class FieldOrderedTupleComparator
implements Comparator<TupleReadable[]>
{
private final List<Integer> sortChannels;
private final List<SortOrder> sortOrders;
public FieldOrderedTupleComparator(List<Integer> sortChannels, List<SortOrder> sortOrders)
{
checkNotNull(sortChannels, "sortChannels is null");
checkNotNull(sortOrders, "sortOrders is null");
checkArgument(sortChannels.size() == sortOrders.size(), "sortFields size (%s) doesn't match sortOrders size (%s)", sortChannels.size(), sortOrders.size());
this.sortChannels = ImmutableList.copyOf(sortChannels);
this.sortOrders = ImmutableList.copyOf(sortOrders);
}
@Override
public int compare(TupleReadable[] leftRow, TupleReadable[] rightRow)
{
for (int index = 0; index < sortChannels.size(); index++) {
int channel = sortChannels.get(index);
SortOrder sortOrder = sortOrders.get(index);
TupleReadable left = leftRow[channel];
TupleReadable right = rightRow[channel];
boolean leftIsNull = left.isNull();
boolean rightIsNull = right.isNull();
if (leftIsNull && rightIsNull) {
return 0;
}
if (leftIsNull) {
return sortOrder.isNullsFirst() ? -1 : 1;
}
if (rightIsNull) {
return sortOrder.isNullsFirst() ? 1 : -1;
}
Type type = left.getTupleInfo().getType();
int comparison;
switch (type) {
case BOOLEAN:
comparison = Boolean.compare(left.getBoolean(), right.getBoolean());
break;
case FIXED_INT_64:
comparison = Long.compare(left.getLong(), right.getLong());
break;
case DOUBLE:
comparison = Double.compare(left.getDouble(), right.getDouble());
break;
case VARIABLE_BINARY:
comparison = left.getSlice().compareTo(right.getSlice());
break;
default:
throw new AssertionError("unimplemented type: " + type);
}
if (comparison != 0) {
return sortOrder.isAscending() ? comparison : -comparison;
}
}
return 0;
}
}