/*
* 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.operator;
import com.facebook.presto.spi.BucketFunction;
import com.facebook.presto.spi.Page;
import java.util.stream.IntStream;
import static java.util.Objects.requireNonNull;
public class PartitionFunction
{
private final BucketFunction bucketFunction;
private final int[] bucketToPartition;
private final int partitionCount;
public PartitionFunction(BucketFunction bucketFunction, int[] bucketToPartition)
{
this.bucketFunction = requireNonNull(bucketFunction, "bucketFunction is null");
this.bucketToPartition = requireNonNull(bucketToPartition, "bucketToPartition is null").clone();
partitionCount = IntStream.of(bucketToPartition).max().getAsInt() + 1;
}
public int getPartitionCount()
{
return partitionCount;
}
/**
* @param functionArguments the arguments to partition function in order (no extra columns)
*/
public int getPartition(Page functionArguments, int position)
{
int bucket = bucketFunction.getBucket(functionArguments, position);
return bucketToPartition[bucket];
}
}