ClickHouse/src/Functions/checkHyperscanRegexp.h
2023-02-09 17:17:35 +00:00

30 lines
716 B
C++

#pragma once
#include <string_view>
#include <vector>
#include <re2_st/re2.h>
namespace DB
{
void checkHyperscanRegexp(const std::vector<std::string_view> & regexps, size_t max_hyperscan_regexp_length, size_t max_hyperscan_regexp_total_length);
/// Regexp evaluation with hyperscan can be slow for certain patterns due to NFA state explosion. Try to identify such patterns on a
/// best-effort basis.
class SlowWithHyperscanChecker
{
public:
SlowWithHyperscanChecker();
bool isSlow(std::string_view regexp);
private:
bool isSlowOneRepeat(std::string_view regexp);
bool isSlowTwoRepeats(std::string_view regexp);
re2_st::RE2 searcher_one_repeat;
re2_st::RE2 searcher_two_repeats;
};
}