main.cpp

/* 
 * Compile with re2c: 
 *  $ re2c main.cpp -o main.re2c.cpp --nested-ifs --bit-vectors --utf-8 --no-debug-info
 *  $ g++ -std=c++17 -O3 -o test_re2c main.re2c.cpp
 */

#include <iostream>
#include <fstream>

bool
match_re2c(char const *YYCURSOR)
{
    char const *YYMARKER;
    /*!re2c
      re2c:define:YYCTYPE = char;
      re2c:yyfill:enable = 0;

      PATTERN = "ABCD"|"DEFGH"|"EFGHI"|"A"{4,};
      END = "\x00";

      * { return false; }
      PATTERN END { return true; }
    */
}

bool
match(std::string const &line)
{
    return match_re2c(line.c_str());
}

int main(int argc, char **argv)
{
    std::ifstream stream{argv[1], std::ifstream::in};
    std::string line;
    while (std::getline(stream, line)) {
        if (match(line)) {
            std::cout << line << '\n';
        }
    }
}

original.cpp

#include <iostream>
#include <fstream>
#include "compile-time-regular-expressions/include/ctre.hpp"

int main(int argc, char **argv)
{
    using namespace ctre::literals;
    auto constexpr re = "ABCD|DEFGH|EFGHI|A{4,}"_ctre;
    std::ifstream stream{argv[1], std::ifstream::in};
    std::string line;
    while (std::getline(stream, line)) {
        if (re.match(line)) {
            std::cout << line << '\n';
        }
    }
}

results.txt

% time ./testctre words2
./testctre words2  4.88s user 0.10s system 99% cpu 6.429 total

% time ./testre2c words2
./testre2c words2  4.77s user 0.09s system 99% cpu 4.866 total

% ls -lah words2 # /usr/share/dict/words duplicated a dozen times
-rw-r--r-- 1 leandros staff 500M Oct 14 12:30 words2