roguish/ansi_parser.rl

#include <fmt/core.h>
#include <string_view>
#include <charconv>
#include "dbc.hpp"
#include <SFML/Graphics.hpp>
#include "ansi_parser.hpp"

using namespace fmt;

%%{
  machine foo;

  action tstart {
    start = fpc;
  }

  action number {
    auto [ptr, ec] = std::from_chars(start, fpc, value);
    dbc::check(ec == std::errc(), "error in number parsing");
  }

  action color24b { }
  action is_fg { target = color; }
  action is_bg { target = bgcolor; }

  action out {
    write(bgcolor, color, fc);
  }

  action reset_fg { color = default_fg; }
  action reset_bg { bgcolor = default_bg; }

  action red { target.r = value; }
  action blue { target.g = value; }
  action green { target.b = value; }
  action start { value = 0; }
  action end { }

  ESC = 0x1B;
  start = ESC "[";
  fg = "38;" %is_fg;
  bg = "48;" %is_bg;
  reset = ("39" %reset_fg | "49" %reset_bg);
  num = digit+ >tstart %number;
  color256 = "5;";
  color24b = "2;";

  ansi = (
      start %start
      (
        reset |
        (fg|bg) color24b num %red ";" num %blue ";" num %green %color24b
      ) "m" %end
  );

  other = (any+ @out -- ESC)*;

  main := (other :> ansi)**;
}%%

%% write data;

bool parse_ansi(std::string_view codes, sf::Color default_fg, sf::Color default_bg, WriteCB write) {
  const char *start = NULL;
  int cs = 0;
  unsigned int value = 0;
  const char *p = codes.data();
  const char *pe = p + codes.size();
  const char *eof = pe;
  sf::Color bgcolor(default_bg);
  sf::Color color(default_fg);
  sf::Color &target = bgcolor;

  %% write init;
  %% write exec;

  return p - pe == 0;
}