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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionHelpers.h>
#include <DataTypes/IDataType.h>
#include <DataTypes/DataTypeTuple.h>
#include <DataTypes/DataTypeArray.h>
#include <Columns/ColumnTuple.h>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnsNumber.h>
#include <Common/assert_cast.h>
#include <memory>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int NOT_FOUND_COLUMN_IN_BLOCK;
}
namespace
{
/** Extract element of tuple by constant index or name. The operation is essentially free.
* Also the function looks through Arrays: you can get Array of tuple elements from Array of Tuples.
*/
class FunctionTupleElement : public IFunction
{
public:
static constexpr auto name = "tupleElement";
static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionTupleElement>(); }
String getName() const override { return name; }
bool isVariadic() const override { return true; }
size_t getNumberOfArguments() const override { return 0; }
bool useDefaultImplementationForConstants() const override { return true; }
ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
bool useDefaultImplementationForNulls() const override { return false; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & 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);
size_t count_arrays = 0;
const IDataType * input_type = arguments[0].type.get();
while (const DataTypeArray * array = checkAndGetDataType<DataTypeArray>(input_type))
{
input_type = array->getNestedType().get();
++count_arrays;
}
const DataTypeTuple * tuple = checkAndGetDataType<DataTypeTuple>(input_type);
if (!tuple)
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"First argument for function {} must be tuple or array of tuple. Actual {}",
getName(),
arguments[0].type->getName());
std::optional<size_t> index = getElementIndex(arguments[1].column, *tuple, number_of_arguments);
if (index.has_value())
{
DataTypePtr return_type = tuple->getElements()[index.value()];
for (; count_arrays; --count_arrays)
return_type = std::make_shared<DataTypeArray>(return_type);
return return_type;
}
else
return arguments[2].type;
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
{
const auto & input_arg = arguments[0];
const IDataType * input_type = input_arg.type.get();
const IColumn * input_col = input_arg.column.get();
bool input_arg_is_const = false;
if (typeid_cast<const ColumnConst *>(input_col))
{
input_col = assert_cast<const ColumnConst *>(input_col)->getDataColumnPtr().get();
input_arg_is_const = true;
}
Columns array_offsets;
while (const DataTypeArray * array_type = checkAndGetDataType<DataTypeArray>(input_type))
{
const ColumnArray * array_col = assert_cast<const ColumnArray *>(input_col);
input_type = array_type->getNestedType().get();
input_col = &array_col->getData();
array_offsets.push_back(array_col->getOffsetsPtr());
}
const DataTypeTuple * input_type_as_tuple = checkAndGetDataType<DataTypeTuple>(input_type);
const ColumnTuple * input_col_as_tuple = checkAndGetColumn<ColumnTuple>(input_col);
if (!input_type_as_tuple || !input_col_as_tuple)
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"First argument for function {} must be tuple or array of tuple. Actual {}", getName(), input_arg.type->getName());
std::optional<size_t> index = getElementIndex(arguments[1].column, *input_type_as_tuple, arguments.size());
if (!index.has_value())
return arguments[2].column;
ColumnPtr res = input_col_as_tuple->getColumns()[index.value()];
/// Wrap into Arrays
for (auto it = array_offsets.rbegin(); it != array_offsets.rend(); ++it)
res = ColumnArray::create(res, *it);
if (input_arg_is_const)
res = ColumnConst::create(res, input_rows_count);
return res;
}
private:
std::optional<size_t> getElementIndex(const ColumnPtr & index_column, const DataTypeTuple & tuple, size_t argument_size) const
{
if (checkAndGetColumnConst<ColumnUInt8>(index_column.get())
|| checkAndGetColumnConst<ColumnUInt16>(index_column.get())
|| checkAndGetColumnConst<ColumnUInt32>(index_column.get())
|| checkAndGetColumnConst<ColumnUInt64>(index_column.get()))
{
const size_t index = index_column->getUInt(0);
if (index > 0 && index <= tuple.getElements().size())
return {index - 1};
else
{
if (argument_size == 2)
throw Exception(ErrorCodes::NOT_FOUND_COLUMN_IN_BLOCK, "Tuple doesn't have element with index '{}'", index);
return std::nullopt;
}
}
else if (const auto * name_col = checkAndGetColumnConst<ColumnString>(index_column.get()))
{
std::optional<size_t> index = tuple.tryGetPositionByName(name_col->getValue<String>());
if (index.has_value())
return index;
else
{
if (argument_size == 2)
throw Exception(ErrorCodes::NOT_FOUND_COLUMN_IN_BLOCK, "Tuple doesn't have element with name '{}'", name_col->getValue<String>());
return std::nullopt;
}
}
else
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"Second argument to {} must be a constant UInt or String",
getName());
}
};
}
REGISTER_FUNCTION(TupleElement)
{
factory.registerFunction<FunctionTupleElement>();
}
}
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