ClickHouse/dbms/src/Common/Collator.cpp

#include <DB/Common/Collator.h>

#pragma GCC diagnostic push
#ifdef __APPLE__
#pragma GCC diagnostic ignored "-Wold-style-cast"
#endif
#include <unicode/ucol.h>
#pragma GCC diagnostic pop

#include <DB/Common/Exception.h>
#include <DB/IO/WriteHelpers.h>
#include <common/Common.h>
#include <Poco/String.h>

Collator::Collator(const std::string & locale_) : locale(Poco::toLower(locale_))
{
	UErrorCode status = U_ZERO_ERROR;

	collator = ucol_open(locale.c_str(), &status);
	if (status != U_ZERO_ERROR)
	{
		ucol_close(collator);
		throw DB::Exception("Unsupported collation locale: " + locale, DB::ErrorCodes::UNSUPPORTED_COLLATION_LOCALE);
	}
}

Collator::~Collator()
{
	ucol_close(collator);
}

int Collator::compare(const char * str1, size_t length1, const char * str2, size_t length2) const
{
	UCharIterator iter1, iter2;
	uiter_setUTF8(&iter1, str1, length1);
	uiter_setUTF8(&iter2, str2, length2);

	UErrorCode status = U_ZERO_ERROR;
	UCollationResult compare_result = ucol_strcollIter(collator, &iter1, &iter2, &status);

	if (status != U_ZERO_ERROR)
		throw DB::Exception("ICU collation comparison failed with error code: " + DB::toString<int>(status),
							DB::ErrorCodes::COLLATION_COMPARISON_FAILED);

	/** Values of enum UCollationResult are equals to what exactly we need:
	 * 	UCOL_EQUAL = 0
	 * 	UCOL_GREATER = 1
	 * 	UCOL_LESS = -1
	 */
	return compare_result;
}

const std::string & Collator::getLocale() const
{
	return locale;
}