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#include <Columns/ColumnsNumber.h>
#include <Columns/ColumnNullable.h>
#include <DataTypes/DataTypesNumber.h>
#include <Functions/FunctionFactory.h>
#include "FunctionArrayMapped.h"
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_COLUMN;
}
enum class ArrayFirstLastStrategy : uint8_t
{
First,
Last
};
enum class ArrayFirstLastElementNotExistsStrategy : uint8_t
{
Default,
Null
};
template <ArrayFirstLastStrategy strategy, ArrayFirstLastElementNotExistsStrategy element_not_exists_strategy>
struct ArrayFirstLastImpl
{
static bool needBoolean() { return false; }
static bool needExpression() { return true; }
static bool needOneArray() { return false; }
static DataTypePtr getReturnType(const DataTypePtr & /*expression_return*/, const DataTypePtr & array_element)
{
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
return makeNullable(array_element);
return array_element;
}
static ColumnPtr createNullableColumn(MutableColumnPtr && column, ColumnUInt8::MutablePtr && null_map)
{
if (auto * nullable_column = typeid_cast<ColumnNullable *>(column.get()))
{
nullable_column->applyNullMap(*null_map);
return std::move(column);
}
return ColumnNullable::create(std::move(column), std::move(null_map));
}
static ColumnPtr execute(const ColumnArray & array, ColumnPtr mapped)
{
const auto * column_filter = typeid_cast<const ColumnUInt8 *>(&*mapped);
if (!column_filter)
{
const auto * column_filter_const = checkAndGetColumnConst<ColumnUInt8>(&*mapped);
if (!column_filter_const)
throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Unexpected type of filter column");
if (column_filter_const->getValue<UInt8>())
{
const auto & offsets = array.getOffsets();
const auto & data = array.getData();
auto out = data.cloneEmpty();
out->reserve(data.size());
size_t offsets_size = offsets.size();
ColumnUInt8::MutablePtr col_null_map_to;
ColumnUInt8::Container * vec_null_map_to = nullptr;
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
{
col_null_map_to = ColumnUInt8::create(offsets_size, false);
vec_null_map_to = &col_null_map_to->getData();
}
for (size_t offset_index = 0; offset_index < offsets_size; ++offset_index)
{
size_t start_offset = offsets[offset_index - 1];
size_t end_offset = offsets[offset_index];
if (end_offset > start_offset)
{
if constexpr (strategy == ArrayFirstLastStrategy::First)
out->insert(data[start_offset]);
else
out->insert(data[end_offset - 1]);
}
else
{
out->insertDefault();
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
(*vec_null_map_to)[offset_index] = true;
}
}
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
return createNullableColumn(std::move(out), std::move(col_null_map_to));
return out;
}
else
{
auto out = array.getData().cloneEmpty();
out->insertManyDefaults(array.size());
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
{
auto col_null_map_to = ColumnUInt8::create(out->size(), true);
return createNullableColumn(std::move(out), std::move(col_null_map_to));
}
return out;
}
}
const auto & filter = column_filter->getData();
const auto & offsets = array.getOffsets();
const auto & data = array.getData();
auto out = data.cloneEmpty();
out->reserve(data.size());
size_t offsets_size = offsets.size();
ColumnUInt8::MutablePtr col_null_map_to;
ColumnUInt8::Container * vec_null_map_to = nullptr;
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
{
col_null_map_to = ColumnUInt8::create(offsets_size, false);
vec_null_map_to = &col_null_map_to->getData();
}
for (size_t offset_index = 0; offset_index < offsets_size; ++offset_index)
{
size_t start_offset = offsets[offset_index - 1];
size_t end_offset = offsets[offset_index];
bool exists = false;
if constexpr (strategy == ArrayFirstLastStrategy::First)
{
for (; start_offset != end_offset; ++start_offset)
{
if (filter[start_offset])
{
out->insert(data[start_offset]);
exists = true;
break;
}
}
}
else
{
for (; end_offset != start_offset; --end_offset)
{
if (filter[end_offset - 1])
{
out->insert(data[end_offset - 1]);
exists = true;
break;
}
}
}
if (!exists)
{
out->insertDefault();
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
(*vec_null_map_to)[offset_index] = true;
}
}
if constexpr (element_not_exists_strategy == ArrayFirstLastElementNotExistsStrategy::Null)
return createNullableColumn(std::move(out), std::move(col_null_map_to));
return out;
}
};
struct NameArrayFirst { static constexpr auto name = "arrayFirst"; };
using ArrayFirstImpl = ArrayFirstLastImpl<ArrayFirstLastStrategy::First, ArrayFirstLastElementNotExistsStrategy::Default>;
using FunctionArrayFirst = FunctionArrayMapped<ArrayFirstImpl, NameArrayFirst>;
struct NameArrayFirstOrNull { static constexpr auto name = "arrayFirstOrNull"; };
using ArrayFirstOrNullImpl = ArrayFirstLastImpl<ArrayFirstLastStrategy::First, ArrayFirstLastElementNotExistsStrategy::Null>;
using FunctionArrayFirstOrNull = FunctionArrayMapped<ArrayFirstOrNullImpl, NameArrayFirstOrNull>;
struct NameArrayLast { static constexpr auto name = "arrayLast"; };
using ArrayLastImpl = ArrayFirstLastImpl<ArrayFirstLastStrategy::Last, ArrayFirstLastElementNotExistsStrategy::Default>;
using FunctionArrayLast = FunctionArrayMapped<ArrayLastImpl, NameArrayLast>;
struct NameArrayLastOrNull { static constexpr auto name = "arrayLastOrNull"; };
using ArrayLastOrNullImpl = ArrayFirstLastImpl<ArrayFirstLastStrategy::Last, ArrayFirstLastElementNotExistsStrategy::Null>;
using FunctionArrayLastOrNull = FunctionArrayMapped<ArrayLastOrNullImpl, NameArrayLastOrNull>;
REGISTER_FUNCTION(ArrayFirst)
{
factory.registerFunction<FunctionArrayFirst>();
factory.registerFunction<FunctionArrayFirstOrNull>();
factory.registerFunction<FunctionArrayLast>();
factory.registerFunction<FunctionArrayLastOrNull>();
}
}
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