std::regex benchmark

readme.md

Compiled with:

clang++  -O3 benchmark.cpp -o benchmark

Results:

10000000 searches with regex:
Number of ? found: 2200000
std::regex: 0.871037 μs (8710.37 ms total)
10000000 searches without regex:
Number of ? found: 2200000
without regex: 0.00527198 μs (52.7198 ms total)

165.22 times the speed of regex

Uses plf_nanotimer.h for timing.

benchmark.cpp

#include <string>
#include <regex>
#include <iostream>
#include <random>
#include <vector>

#include "plf_nanotimer.h"

bool find_regex (const std::string& input)
{
  const static std::regex re("[^?]+\\?.*");
  return std::regex_match(input, re);
}

bool find_no_regex (const std::string& input)
{
    return input.find('?') != std::string::npos;
}

int main (int argc, char* argv[])
{
    const int count = 100000;

    std::vector<std::string> inputs{
        {"https://www.example.com/"},
        {"http://attraction.example.com/"},
        {"http://example.org/"},
        {"http://www.example.com/?babies=afterthought&brass=basket"},
        {"https://example.com/"},
        {"https://www.example.org/"},
        {"https://www.example.com/?brake=air&ball=baseball"},
        {"https://www.example.com/bird"},
        {"http://aunt.example.com/arch"},
        {"http://anger.example.com/"},
        {"https://www.example.org/"},
        {"https://blade.example.com/bee/bikes"},
        {"http://www.example.com/?bit=advertisement&attraction=border#berry"},
        {"https://example.com/"},
        {"https://www.example.com/"},
        {"http://www.example.com/anger"},
        {"https://www.example.com/?afterthought=back&bridge=basketball"},
        {"http://bikes.example.com/"},
        {"http://example.com/"},
        {"https://example.com/blade.php#badge"},
        {"http://www.example.com/?arch=boy"},
        {"https://aunt.example.net/attraction"},
        {"https://www.example.net/bait"},
        {"https://www.example.net/bait/ants.php"},
        {"https://example.com/action/arm.html"},
        {"https://www.example.com/?blade=attraction&berry=basket"},
        {"https://example.edu/"},
        {"http://www.example.org/bag"},
        {"http://example.com/bells/airplane.html?battle=animal&boundary=back#bedroom"},
        {"https://example.com/birthday/believe?baby=border#balance"},
        {"https://example.com/adjustment"},
        {"https://belief.example.com/"},
        {"https://example.com/"},
        {"http://www.example.com/beef.php"},
        {"http://example.com/beginner"},
        {"http://www.example.com/"},
        {"https://www.example.com/boy"},
        {"http://www.example.com/bells#blow"},
        {"http://www.example.com/brother/balance.htm"},
        {"https://www.example.net/?brake=blow&bite=bait"},
        {"http://www.example.com/"},
        {"https://base.example.com/#bedroom"},
        {"https://www.example.com/"},
        {"https://example.com/"},
        {"https://example.com/bed.html"},
        {"http://www.example.edu/"},
        {"https://www.example.org/arch"},
        {"https://www.example.com/berry/basketball"},
        {"https://www.example.com/"},
        {"http://www.example.com/boundary#account"},
        {"https://www.example.com/attraction.php?bait=apparatus"},
        {"http://babies.example.com/?airport=ants"},
        {"https://www.example.com/balance.php"},
        {"http://example.com/?bedroom=act&angle=angle"},
        {"https://attack.example.com/behavior"},
        {"http://www.example.com/?alarm=bed"},
        {"https://behavior.example.com/attraction/blood"},
        {"http://example.com/aunt/arch.html#basketball"},
        {"http://www.example.com/argument.html?ants=airport&activity=brass"},
        {"http://base.example.com/bedroom?bite=acoustics&arch=basin"},
        {"http://example.com/"},
        {"https://www.example.com/bear"},
        {"https://www.example.edu/advertisement/breath.html?badge=argument"},
        {"https://www.example.com/branch.php?brick=appliance&birth=authority"},
        {"https://www.example.com/birds/bait"},
        {"http://www.example.net/"},
        {"http://www.example.com/beds"},
        {"https://www.example.net/angle.php"},
        {"https://www.example.com/"},
        {"https://example.com/basketball"},
        {"http://authority.example.net/baseball"},
        {"https://example.com/actor/bath.php"},
        {"https://example.com/base/battle"},
        {"http://www.example.com/brick.aspx"},
        {"http://www.example.com/bedroom/blade.php"},
        {"http://example.com/act.php"},
        {"https://www.example.org/adjustment/achiever#bike"},
        {"https://example.com/"},
        {"http://www.example.com/"},
        {"http://www.example.com/boy/berry.html"},
        {"https://www.example.com/bear"},
        {"https://www.example.edu/?bells=act#bat"},
        {"https://example.net/"},
        {"http://babies.example.com/"},
        {"http://example.com/"},
        {"http://amusement.example.com/"},
        {"https://box.example.com/"},
        {"http://example.com/"},
        {"http://example.com/?beef=basin"},
        {"http://www.example.org/"},
        {"http://www.example.com/beds/baby?airplane=berry"},
        {"https://www.example.com/advertisement/apparel.php"},
        {"http://www.example.com/"},
        {"https://bead.example.org/bottle.html?blade=animal"},
        {"https://www.example.com/aftermath.html#bells"},
        {"http://www.example.org/"},
        {"https://bait.example.com/?apparatus=authority"},
        {"http://example.com/"},
        {"http://www.example.com/advertisement/base.html"},
        {"http://www.example.com/brick/border"},
    };

    unsigned total = (count * inputs.size());

    double regex_results;
    double no_regex_results;
    {
        plf::nanotimer timer;
        std::cout << total << " searches with regex:\n";
        int counter = 0;
        timer.start();
        for (int i = 0; i < count; i++) {
            for (const auto& input : inputs) {
                if (find_regex(input)) {
                    counter++;
                }
            }
        }

        regex_results = timer.get_elapsed_us();
        
        std::cout << "Number of ? found: " << counter << "\n";
        std::cout << "std::regex: " << (regex_results / total) << " μs (" << (regex_results / 1000) << " ms total)\n";
    }
    {
        plf::nanotimer timer;
        std::cout << total << " searches without regex:\n";
        int counter = 0;
        timer.start();
        for (int i = 0; i < count; i++) {
            for (const auto& input : inputs) {
                if (find_no_regex(input)) {
                    counter++;
                }
            }
        }

        no_regex_results = timer.get_elapsed_us();
        
        std::cout << "Number of ? found: " << counter << "\n";
        std::cout << "without regex: " << (no_regex_results / total) << " μs (" << (no_regex_results / 1000) << " ms total)\n";
    }
    std::cout << "\n";
    std::cout << (regex_results / no_regex_results) << " times the speed of regex\n";

    return 0;
}