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Regex literals

Flags
Saving string in match results
Examples

regex_literal is a templated user defined literals wrapper for std::regex. "regex_search" and "regex_match" functions are packed into a new structure 'struct_rm' to be able to write regex request in only one line.

Both char and wchar_t are compatible. It can be extended using struct_rm template if needed.

To use regex_literals, include the header, type using namespace regex_literals; and use _rg after a string literal to transform it to a struct_rm.

Flags

struct_rm supports regex flags as "/regex/flags"_rg which follows std::regex_constants::syntax_option_type flags. Here is available flags:

  • i : icase
  • b : nosubs
  • o : optimize
  • c : collate
  • E : ECMAScript
  • B : basic
  • X : extended
  • A : awk
  • G : grep
  • P : egrep

C++17 flags compatibility:

  • m : multiline

Flags can be disabled using #define REGEX_LITERALS_FLAGS 0 before including regex_literals.

Saving string in match results

Another feature is the capability to save string into match_results with match_results_ws so a regex request doesn't need to get a string reference for match results (well... it still needs string reference but in this case, it's stored in match_results).

Examples

#include <iostream>
#include "regex_literals.h"
int main()
{
    using namespace regex_literals;
    /// simple match
    if ("abc"_rg.match("abc"))
        std::cout << "abc=abc: ok" << std::endl;
    /// simple case sensitive match  
    if ("abc"_rg.match("ABC"))
        std::cout << "abc=ABC: ok"<< std::endl;
    /// simple match with case insensitive flag
    if ("/abc/i"_rg.match("ABC"))
        std::cout << "abc=ABC (insensitive case): ok"<< std::endl;
    /// search 
    if ("/abc/i"_rg.search("xyzABC123"))
        std::cout << "xyzABC123 contains abc (insensitive case): ok"<< std::endl;

    /// get results
    std::smatch sm;
    std::string mystr="     xyzABC123  ";
    if (R"(/\s*(\w+)\s*/i)"_rg.search(mystr, sm))
        std::cout << "trim word: ok: '" << sm[1] << "'" << std::endl;
    
    /// save string in match results and get results
    match_results_ws<char> sm_ws;
    if (R"(\s*(\w+)\s*)"_rg.search("    mystr       ", sm_ws))
        std::cout << "trim word: ok: '" << sm_ws[1] << "'" << std::endl;
    if (R"(\s*(\w+)\s*)"_rg.search("    new_str       ", sm_ws))
        std::cout << "trim word: ok: '" << sm_ws[1] << "'" << std::endl;
    return 0;
}