ClickHouse/dbms/include/DB/Functions/Regexps.h

#pragma once
#include <DB/Common/OptimizedRegularExpression.h>
#include <DB/Functions/ObjectPool.h>
#include <DB/Functions/likePatternToRegexp.h>
#include <DB/Common/ProfileEvents.h>


namespace ProfileEvents
{
	extern const Event RegexpCreated;
}


namespace DB {


namespace Regexps
{
	using Regexp = OptimizedRegularExpressionImpl<false>;
	using Pool = ObjectPoolMap<Regexp, String>;

	template <bool like>
	inline Regexp createRegexp(const std::string & pattern, int flags) { return {pattern, flags}; }

	template <>
	inline Regexp createRegexp<true>(const std::string & pattern, int flags) { return {likePatternToRegexp(pattern), flags}; }

	template <bool like, bool no_capture>
	inline Pool::Pointer get(const std::string & pattern)
	{
		/// C++11 has thread-safe function-local statics on most modern compilers.
		static Pool known_regexps;	/// Разные переменные для разных параметров шаблона.

		return known_regexps.get(pattern, [&pattern]
		{
			int flags = OptimizedRegularExpression::RE_DOT_NL;
			if (no_capture)
				flags |= OptimizedRegularExpression::RE_NO_CAPTURE;

			ProfileEvents::increment(ProfileEvents::RegexpCreated);
			return new Regexp{createRegexp<like>(pattern, flags)};
		});
	}
}

}