/*
* 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.PrestoException;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.function.Description;
import com.facebook.presto.spi.function.ScalarFunction;
import com.facebook.presto.spi.function.SqlNullable;
import com.facebook.presto.spi.function.SqlType;
import com.facebook.presto.spi.function.TypeParameter;
import com.facebook.presto.spi.type.Type;
import io.airlift.slice.Slice;
import static com.facebook.presto.spi.StandardErrorCode.INVALID_FUNCTION_ARGUMENT;
import static java.lang.Math.toIntExact;
@ScalarFunction("element_at")
@Description("Get element of array at given index")
public final class ArrayElementAtFunction
{
private ArrayElementAtFunction() {}
@TypeParameter("E")
@SqlNullable
@SqlType("E")
public static Void voidElementAt(@SqlType("array(E)") Block array, @SqlType("bigint") long index)
{
checkedIndexToBlockPosition(array, index);
return null;
}
@TypeParameter("E")
@SqlNullable
@SqlType("E")
public static Long longElementAt(@TypeParameter("E") Type elementType, @SqlType("array(E)") Block array, @SqlType("bigint") long index)
{
int position = checkedIndexToBlockPosition(array, index);
if (position == -1) {
return null;
}
if (array.isNull(position)) {
return null;
}
return elementType.getLong(array, position);
}
@TypeParameter("E")
@SqlNullable
@SqlType("E")
public static Boolean booleanElementAt(@TypeParameter("E") Type elementType, @SqlType("array(E)") Block array, @SqlType("bigint") long index)
{
int position = checkedIndexToBlockPosition(array, index);
if (position == -1) {
return null;
}
if (array.isNull(position)) {
return null;
}
return elementType.getBoolean(array, position);
}
@TypeParameter("E")
@SqlNullable
@SqlType("E")
public static Double doubleElementAt(@TypeParameter("E") Type elementType, @SqlType("array(E)") Block array, @SqlType("bigint") long index)
{
int position = checkedIndexToBlockPosition(array, index);
if (position == -1) {
return null;
}
if (array.isNull(position)) {
return null;
}
return elementType.getDouble(array, position);
}
@TypeParameter("E")
@SqlNullable
@SqlType("E")
public static Slice sliceElementAt(@TypeParameter("E") Type elementType, @SqlType("array(E)") Block array, @SqlType("bigint") long index)
{
int position = checkedIndexToBlockPosition(array, index);
if (position == -1) {
return null;
}
if (array.isNull(position)) {
return null;
}
return elementType.getSlice(array, position);
}
@TypeParameter("E")
@SqlNullable
@SqlType("E")
public static Block blockElementAt(@TypeParameter("E") Type elementType, @SqlType("array(E)") Block array, @SqlType("bigint") long index)
{
int position = checkedIndexToBlockPosition(array, index);
if (position == -1) {
return null;
}
if (array.isNull(position)) {
return null;
}
return (Block) elementType.getObject(array, position);
}
/**
* @return PrestoException if the index is 0, -1 if the index is out of range (to tell the calling function to return null), and the element position otherwise.
*/
private static int checkedIndexToBlockPosition(Block block, long index)
{
int arrayLength = block.getPositionCount();
if (index == 0) {
throw new PrestoException(INVALID_FUNCTION_ARGUMENT, "SQL array indices start at 1");
}
if (Math.abs(index) > arrayLength) {
return -1; // -1 indicates that the element is out of range and "ELEMENT_AT" should return null
}
if (index > 0) {
return toIntExact(index - 1);
}
else {
return toIntExact(arrayLength + index);
}
}
}