ClickHouse/src/Functions/splitByChar.cpp

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2023-11-11 01:21:24 +00:00
#include <Columns/ColumnConst.h>
#include <Functions/FunctionHelpers.h>
#include <Functions/FunctionTokens.h>
#include <Functions/FunctionFactory.h>
#include <Common/StringUtils/StringUtils.h>
#include <Common/assert_cast.h>
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
extern const int ILLEGAL_COLUMN;
}
/** Functions that split strings into an array of strings or vice versa.
*
* splitByChar(sep, s[, max_substrings])
*/
namespace
{
using Pos = const char *;
class SplitByCharImpl
{
private:
Pos pos;
Pos end;
char separator;
std::optional<size_t> max_splits;
size_t splits;
bool max_substrings_includes_remaining_string;
public:
static constexpr auto name = "splitByChar";
static bool isVariadic() { return true; }
static size_t getNumberOfArguments() { return 0; }
static void checkArguments(const IFunction & func, const ColumnsWithTypeAndName & arguments)
{
checkArgumentsWithSeparatorAndOptionalMaxSubstrings(func, arguments);
}
static constexpr auto strings_argument_position = 1uz;
void init(const ColumnsWithTypeAndName & arguments, bool max_substrings_includes_remaining_string_)
{
const ColumnConst * col = checkAndGetColumnConstStringOrFixedString(arguments[0].column.get());
if (!col)
throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Illegal column {} of first argument of function {}. "
"Must be constant string.", arguments[0].column->getName(), name);
String sep_str = col->getValue<String>();
if (sep_str.size() != 1)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Illegal separator for function {}. Must be exactly one byte.", name);
separator = sep_str[0];
max_substrings_includes_remaining_string = max_substrings_includes_remaining_string_;
max_splits = extractMaxSplits(arguments, 2);
}
void set(Pos pos_, Pos end_)
{
pos = pos_;
end = end_;
splits = 0;
}
bool get(Pos & token_begin, Pos & token_end)
{
if (!pos)
return false;
token_begin = pos;
if (max_splits)
{
if (max_substrings_includes_remaining_string)
{
if (splits == *max_splits - 1)
{
token_end = end;
pos = nullptr;
return true;
}
}
else
if (splits == *max_splits)
return false;
}
pos = reinterpret_cast<Pos>(memchr(pos, separator, end - pos));
if (pos)
{
token_end = pos;
++pos;
++splits;
}
else
token_end = end;
return true;
}
};
using FunctionSplitByChar = FunctionTokens<SplitByCharImpl>;
}
REGISTER_FUNCTION(SplitByChar)
{
factory.registerFunction<FunctionSplitByChar>();
}
}