ClickHouse/src/Functions/toFixedString.h
2020-07-21 16:58:07 +03:00

111 lines
4.2 KiB
C++

#include <Functions/IFunctionImpl.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/DataTypeFixedString.h>
#include <DataTypes/DataTypesNumber.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnFixedString.h>
#include <IO/WriteHelpers.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_COLUMN;
extern const int TOO_LARGE_STRING_SIZE;
extern const int NOT_IMPLEMENTED;
}
/** Conversion to fixed string is implemented only for strings.
*/
class FunctionToFixedString : public IFunction
{
public:
static constexpr auto name = "toFixedString";
static FunctionPtr create(const Context &) { return std::make_shared<FunctionToFixedString>(); }
static FunctionPtr create() { return std::make_shared<FunctionToFixedString>(); }
String getName() const override
{
return name;
}
size_t getNumberOfArguments() const override { return 2; }
bool isInjective(const Block &) const override { return true; }
DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
{
if (!isUnsignedInteger(arguments[1].type))
throw Exception("Second argument for function " + getName() + " must be unsigned integer", ErrorCodes::ILLEGAL_COLUMN);
if (!arguments[1].column)
throw Exception("Second argument for function " + getName() + " must be constant", ErrorCodes::ILLEGAL_COLUMN);
if (!isStringOrFixedString(arguments[0].type))
throw Exception(getName() + " is only implemented for types String and FixedString", ErrorCodes::NOT_IMPLEMENTED);
const size_t n = arguments[1].column->getUInt(0);
return std::make_shared<DataTypeFixedString>(n);
}
bool useDefaultImplementationForConstants() const override { return true; }
ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) const override
{
const auto n = block.getByPosition(arguments[1]).column->getUInt(0);
return executeForN(block, arguments, result, n);
}
static void executeForN(Block & block, const ColumnNumbers & arguments, const size_t result, const size_t n)
{
const auto & column = block.getByPosition(arguments[0]).column;
if (const auto column_string = checkAndGetColumn<ColumnString>(column.get()))
{
auto column_fixed = ColumnFixedString::create(n);
auto & out_chars = column_fixed->getChars();
const auto & in_chars = column_string->getChars();
const auto & in_offsets = column_string->getOffsets();
out_chars.resize_fill(in_offsets.size() * n);
for (size_t i = 0; i < in_offsets.size(); ++i)
{
const size_t off = i ? in_offsets[i - 1] : 0;
const size_t len = in_offsets[i] - off - 1;
if (len > n)
throw Exception("String too long for type FixedString(" + toString(n) + ")",
ErrorCodes::TOO_LARGE_STRING_SIZE);
memcpy(&out_chars[i * n], &in_chars[off], len);
}
block.getByPosition(result).column = std::move(column_fixed);
}
else if (const auto column_fixed_string = checkAndGetColumn<ColumnFixedString>(column.get()))
{
const auto src_n = column_fixed_string->getN();
if (src_n > n)
throw Exception{"String too long for type FixedString(" + toString(n) + ")", ErrorCodes::TOO_LARGE_STRING_SIZE};
auto column_fixed = ColumnFixedString::create(n);
auto & out_chars = column_fixed->getChars();
const auto & in_chars = column_fixed_string->getChars();
const auto size = column_fixed_string->size();
out_chars.resize_fill(size * n);
for (size_t i = 0; i < size; ++i)
memcpy(&out_chars[i * n], &in_chars[i * src_n], src_n);
block.getByPosition(result).column = std::move(column_fixed);
}
else
throw Exception("Unexpected column: " + column->getName(), ErrorCodes::ILLEGAL_COLUMN);
}
};
}