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#include <Columns/ColumnConst.h>
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/getLeastSupertype.h>
#include <Functions/FunctionFactory.h>
#include <Functions/IFunction.h>
#include <IO/WriteHelpers.h>
#include <Interpreters/castColumn.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int ARGUMENT_OUT_OF_BOUND;
}
namespace
{
// Implements function, giving value for column within range of given
// Example:
// | c1 |
// | 10 |
// | 20 |
// SELECT c1, neighbor(c1, 1) as c2:
// | c1 | c2 |
// | 10 | 20 |
// | 20 | 0 |
class FunctionNeighbor : public IFunction
{
public:
static constexpr auto name = "neighbor";
static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionNeighbor>(); }
/// Get the name of the function.
String getName() const override { return name; }
size_t getNumberOfArguments() const override { return 0; }
bool isVariadic() const override { return true; }
bool isStateful() const override { return true; }
bool isDeterministic() const override { return false; }
bool isDeterministicInScopeOfQuery() const override { return false; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
bool useDefaultImplementationForNulls() const override { return false; }
bool useDefaultImplementationForConstants() const override { return false; }
/// We do not use default implementation for LowCardinality because this is not a pure function.
/// If used, optimization for LC may execute function only for dictionary, which gives wrong result.
bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
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 from 2 to 3",
getName(), number_of_arguments);
// second argument must be an integer
if (!isInteger(arguments[1]))
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"Illegal type {} of second argument of function {} - should be an integer", arguments[1]->getName(), getName());
else if (arguments[1]->isNullable())
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"Illegal type {} of second argument of function {} - can not be Nullable", arguments[1]->getName(), getName());
// check that default value column has supertype with first argument
if (number_of_arguments == 3)
return getLeastSupertype(DataTypes{arguments[0], arguments[2]});
return arguments[0];
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
{
const ColumnWithTypeAndName & source_elem = arguments[0];
const ColumnWithTypeAndName & offset_elem = arguments[1];
bool has_defaults = arguments.size() == 3;
ColumnPtr source_column_casted = castColumn(source_elem, result_type);
ColumnPtr offset_column = offset_elem.column;
ColumnPtr default_column_casted;
if (has_defaults)
{
const ColumnWithTypeAndName & default_elem = arguments[2];
default_column_casted = castColumn(default_elem, result_type);
}
bool source_is_constant = isColumnConst(*source_column_casted);
bool offset_is_constant = isColumnConst(*offset_column);
bool default_is_constant = false;
if (has_defaults)
default_is_constant = isColumnConst(*default_column_casted);
if (source_is_constant)
source_column_casted = assert_cast<const ColumnConst &>(*source_column_casted).getDataColumnPtr();
if (offset_is_constant)
offset_column = assert_cast<const ColumnConst &>(*offset_column).getDataColumnPtr();
if (default_is_constant)
default_column_casted = assert_cast<const ColumnConst &>(*default_column_casted).getDataColumnPtr();
if (offset_is_constant)
{
/// Optimization for the case when we can copy many values at once.
Int64 offset = offset_column->getInt(0);
/// Protection from possible overflow.
if (unlikely(offset > (1 << 30) || offset < -(1 << 30)))
throw Exception(ErrorCodes::ARGUMENT_OUT_OF_BOUND, "Too large offset: {} in function {}", offset, getName());
auto result_column = result_type->createColumn();
auto insert_range_from = [&](bool is_const, const ColumnPtr & src, Int64 begin, Int64 size)
{
/// Saturation of bounds.
if (begin < 0)
{
size += begin;
begin = 0;
}
if (size <= 0)
return;
if (size > static_cast<Int64>(input_rows_count))
size = input_rows_count;
if (!src)
{
for (Int64 i = 0; i < size; ++i)
result_column->insertDefault();
}
else if (is_const)
{
for (Int64 i = 0; i < size; ++i)
result_column->insertFrom(*src, 0);
}
else
{
result_column->insertRangeFrom(*src, begin, size);
}
};
if (offset == 0)
{
/// Degenerate case, just copy source column as is.
return source_is_constant
? ColumnConst::create(source_column_casted, input_rows_count)
: source_column_casted;
}
else if (offset > 0)
{
insert_range_from(source_is_constant, source_column_casted, offset, static_cast<Int64>(input_rows_count) - offset);
insert_range_from(default_is_constant, default_column_casted, static_cast<Int64>(input_rows_count) - offset, offset);
return result_column;
}
else
{
insert_range_from(default_is_constant, default_column_casted, 0, -offset);
insert_range_from(source_is_constant, source_column_casted, 0, static_cast<Int64>(input_rows_count) + offset);
return result_column;
}
}
else
{
auto result_column = result_type->createColumn();
for (size_t row = 0; row < input_rows_count; ++row)
{
Int64 offset = offset_column->getInt(row);
/// Protection from possible overflow.
if (unlikely(offset > (1 << 30) || offset < -(1 << 30)))
throw Exception(ErrorCodes::ARGUMENT_OUT_OF_BOUND, "Too large offset: {} in function {}", offset, getName());
Int64 src_idx = row + offset;
if (src_idx >= 0 && src_idx < static_cast<Int64>(input_rows_count))
result_column->insertFrom(*source_column_casted, source_is_constant ? 0 : src_idx);
else if (has_defaults)
result_column->insertFrom(*default_column_casted, default_is_constant ? 0 : row);
else
result_column->insertDefault();
}
return result_column;
}
}
};
}
REGISTER_FUNCTION(Neighbor)
{
factory.registerFunction<FunctionNeighbor>();
}
}
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