/*
* 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.scalar;
import com.facebook.presto.spi.PageBuilder;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.function.Description;
import com.facebook.presto.spi.function.OperatorDependency;
import com.facebook.presto.spi.function.ScalarFunction;
import com.facebook.presto.spi.function.SqlType;
import com.facebook.presto.spi.function.TypeParameter;
import com.facebook.presto.spi.type.StandardTypes;
import com.facebook.presto.spi.type.Type;
import com.google.common.collect.ImmutableList;
import com.google.common.primitives.Ints;
import java.lang.invoke.MethodHandle;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import static com.facebook.presto.spi.function.OperatorType.LESS_THAN;
@ScalarFunction("array_sort")
@Description("Sorts the given array in ascending order according to the natural ordering of its elements.")
public final class ArraySortFunction
{
private final PageBuilder pageBuilder;
private static final int INITIAL_LENGTH = 128;
private List<Integer> positions = Ints.asList(new int[INITIAL_LENGTH]);
@TypeParameter("E")
public ArraySortFunction(@TypeParameter("E") Type elementType)
{
pageBuilder = new PageBuilder(ImmutableList.of(elementType));
}
@TypeParameter("E")
@SqlType("array(E)")
public Block sort(
@OperatorDependency(operator = LESS_THAN, returnType = StandardTypes.BOOLEAN, argumentTypes = {"E", "E"}) MethodHandle lessThanFunction,
@TypeParameter("E") Type type,
@SqlType("array(E)") Block block)
{
int arrayLength = block.getPositionCount();
if (positions.size() < arrayLength) {
positions = Ints.asList(new int[arrayLength]);
}
for (int i = 0; i < arrayLength; i++) {
positions.set(i, i);
}
Collections.sort(positions.subList(0, arrayLength), new Comparator<Integer>()
{
@Override
public int compare(Integer p1, Integer p2)
{
boolean nullLeft = block.isNull(p1);
boolean nullRight = block.isNull(p2);
if (nullLeft && nullRight) {
return 0;
}
if (nullLeft) {
return 1;
}
if (nullRight) {
return -1;
}
//TODO: This could be quite slow, it should use parametric equals
return type.compareTo(block, p1, block, p2);
}
});
if (pageBuilder.isFull()) {
pageBuilder.reset();
}
BlockBuilder blockBuilder = pageBuilder.getBlockBuilder(0);
for (int i = 0; i < arrayLength; i++) {
type.appendTo(block, positions.get(i), blockBuilder);
}
pageBuilder.declarePositions(arrayLength);
return blockBuilder.getRegion(blockBuilder.getPositionCount() - arrayLength, arrayLength);
}
}