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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <Functions/GatherUtils/GatherUtils.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeNullable.h>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnConst.h>
#include <Common/typeid_cast.h>
#include <IO/WriteHelpers.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}
/** arraySlice(arr, offset, length) - make slice of array. Offsets and length may be < 0 or Null
* - if offset < 0, indexation from right element
* - if length < 0, length = len(array) - (positive_index(offset) - 1) + length
* indexation:
* [ 1, 2, 3, 4, 5, 6]
* [-6, -5, -4, -3, -2, -1]
* examples:
* arraySlice([1, 2, 3, 4, 5, 6], -4, 2) -> [3, 4]
* arraySlice([1, 2, 3, 4, 5, 6], 2, -1) -> [2, 3, 4, 5] (6 - (2 - 1) + (-1) = 4)
* arraySlice([1, 2, 3, 4, 5, 6], -5, -1) = arraySlice([1, 2, 3, 4, 5, 6], 2, -1) -> [2, 3, 4, 5]
*/
class FunctionArraySlice : public IFunction
{
public:
static constexpr auto name = "arraySlice";
static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionArraySlice>(); }
String getName() const override { return name; }
bool isVariadic() const override { return true; }
size_t getNumberOfArguments() const override { return 0; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return true; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
const size_t number_of_arguments = arguments.size();
if (number_of_arguments < 2 || number_of_arguments > 3)
throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
"Number of arguments for function {} doesn't match: passed {}, should be 2 or 3",
getName(), number_of_arguments);
if (arguments[0]->onlyNull())
return arguments[0];
const auto * array_type = typeid_cast<const DataTypeArray *>(arguments[0].get());
if (!array_type)
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"First argument for function {} must be an array but it has type {}.",
getName(), arguments[0]->getName());
for (size_t i = 1; i < number_of_arguments; ++i)
{
if (!isInteger(removeNullable(arguments[i])) && !arguments[i]->onlyNull())
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"Argument {} for function {} must be integer but it has type {}.",
i, getName(), arguments[i]->getName());
}
return arguments[0];
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & return_type, size_t input_rows_count) const override
{
if (return_type->onlyNull())
return return_type->createColumnConstWithDefaultValue(input_rows_count);
auto array_column = arguments[0].column;
const auto & offset_column = arguments[1].column;
const auto & length_column = arguments.size() > 2 ? arguments[2].column : nullptr;
std::unique_ptr<GatherUtils::IArraySource> source;
size_t size = array_column->size();
bool is_const = false;
if (const auto * const_array_column = typeid_cast<const ColumnConst *>(array_column.get()))
{
is_const = true;
array_column = const_array_column->getDataColumnPtr();
}
if (const auto * argument_column_array = typeid_cast<const ColumnArray *>(array_column.get()))
source = GatherUtils::createArraySource(*argument_column_array, is_const, size);
else
throw Exception(ErrorCodes::LOGICAL_ERROR, "First arguments for function {} must be array.", getName());
ColumnArray::MutablePtr sink;
if (offset_column->onlyNull())
{
if (!length_column || length_column->onlyNull())
{
return arguments[0].column;
}
else if (isColumnConst(*length_column))
sink = GatherUtils::sliceFromLeftConstantOffsetBounded(*source, 0, length_column->getInt(0));
else
{
auto const_offset_column = ColumnConst::create(ColumnInt8::create(1, 1), size);
sink = GatherUtils::sliceDynamicOffsetBounded(*source, *const_offset_column, *length_column);
}
}
else if (isColumnConst(*offset_column))
{
ssize_t offset = offset_column->getUInt(0);
if (!length_column || length_column->onlyNull())
{
if (offset > 0)
sink = GatherUtils::sliceFromLeftConstantOffsetUnbounded(*source, static_cast<size_t>(offset - 1));
else
sink = GatherUtils::sliceFromRightConstantOffsetUnbounded(*source, -static_cast<size_t>(offset));
}
else if (isColumnConst(*length_column))
{
ssize_t length = length_column->getInt(0);
if (offset > 0)
sink = GatherUtils::sliceFromLeftConstantOffsetBounded(*source, static_cast<size_t>(offset - 1), length);
else
sink = GatherUtils::sliceFromRightConstantOffsetBounded(*source, -static_cast<size_t>(offset), length);
}
else
sink = GatherUtils::sliceDynamicOffsetBounded(*source, *offset_column, *length_column);
}
else
{
if (!length_column || length_column->onlyNull())
sink = GatherUtils::sliceDynamicOffsetUnbounded(*source, *offset_column);
else
sink = GatherUtils::sliceDynamicOffsetBounded(*source, *offset_column, *length_column);
}
return sink;
}
bool useDefaultImplementationForConstants() const override { return true; }
bool useDefaultImplementationForNulls() const override { return false; }
};
REGISTER_FUNCTION(ArraySlice)
{
factory.registerFunction<FunctionArraySlice>();
}
}
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