/*
* 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.operator.aggregation.TypedSet;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.block.BlockBuilderStatus;
import com.facebook.presto.spi.function.Description;
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.Type;
import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
import it.unimi.dsi.fastutil.longs.LongSet;
import static com.facebook.presto.spi.type.BigintType.BIGINT;
@ScalarFunction("array_distinct")
@Description("Remove duplicate values from the given array")
public final class ArrayDistinctFunction
{
private ArrayDistinctFunction() {}
@TypeParameter("E")
@SqlType("array(E)")
public static Block distinct(@TypeParameter("E") Type type, @SqlType("array(E)") Block array)
{
if (array.getPositionCount() < 2) {
return array;
}
if (array.getPositionCount() == 2) {
if (type.equalTo(array, 0, array, 1)) {
return array.getSingleValueBlock(0);
}
else {
return array;
}
}
TypedSet typedSet = new TypedSet(type, array.getPositionCount());
BlockBuilder distinctElementBlockBuilder = type.createBlockBuilder(new BlockBuilderStatus(), array.getPositionCount());
for (int i = 0; i < array.getPositionCount(); i++) {
if (!typedSet.contains(array, i)) {
typedSet.add(array, i);
type.appendTo(array, i, distinctElementBlockBuilder);
}
}
return distinctElementBlockBuilder.build();
}
@SqlType("array(bigint)")
public static Block bigintDistinct(@SqlType("array(bigint)") Block array)
{
if (array.getPositionCount() == 0) {
return array;
}
boolean containsNull = false;
LongSet set = new LongOpenHashSet(array.getPositionCount());
BlockBuilder distinctElementBlockBuilder = BIGINT.createBlockBuilder(new BlockBuilderStatus(), array.getPositionCount());
for (int i = 0; i < array.getPositionCount(); i++) {
if (array.isNull(i)) {
if (!containsNull) {
containsNull = true;
distinctElementBlockBuilder.appendNull();
}
continue;
}
long value = BIGINT.getLong(array, i);
if (set.add(value)) {
BIGINT.writeLong(distinctElementBlockBuilder, value);
}
}
return distinctElementBlockBuilder.build();
}
}