https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85472
--- Comment #14 from Tim Shen <timshen at gcc dot gnu.org> ---
How fast does your prototype run on the following example?
((10)|(11)|(12)|...|(98)|(99))* matching "10111213141516...9899"
how about this:
((100)|(101)|(102)|...|(998)|(999))* matching "100101102...998999"
where "..." are the skipped strings that follow the surrounding pattern.
For the record, for the 100-999 case, libstdc++ takes 0.112 seconds given a
proper stack limit. libc++ takes 6.386 seconds.
I have a C++ test case for this:
#include <regex>
#include <string>
#include <iostream>
constexpr int kStart = 100;
constexpr int kEnd = 1000;
int main() {
std::regex re;
{
std::string re_string;
re_string += '(';
re_string += std::string("(") + std::to_string(kStart) + ")";
for (int i = kStart + 1; i < kEnd; i++) {
re_string += '|';
re_string += '(';
re_string += std::to_string(i);
re_string += ')';
}
re_string += ')';
re_string += '*';
re.assign(re_string);
}
std::string s;
for (int i = kStart; i < kEnd; i++) {
s += std::to_string(i);
}
std::smatch m;
std::cout << std::regex_match(s, m, re) << "\n";
for (const auto p : m) {
std::cout << p << " ";
}
std::cout << "\n";
return 0;
}
