matchElements function

Implementation

void matchElements(String value) {
  /// WARNING: DO NOT USE LOOKBEHIND it is unsupported in safari and other browsers.
  RegExp bdO = RegExp(
      r"(([ *_^#`])|\\)(\*\*)(?![ *])"); // \ will escape the mandatory space before or after a character.
  RegExp bdC = RegExp(r"(\S)(\*\*(?=\W|\\))");
  RegExp itO = RegExp(r"(([ *_^#`\\])|\\)(\*)(?![ *])");
  RegExp itC = RegExp(r"(\S)(\*(?=\W|\\))");
  RegExp sbO = RegExp(r"(([ *_^#`\\])|\\)(\^\^)(?![ ^])");
  RegExp sbC = RegExp(r"(\S)(\^\^(?=\W|\\))");
  RegExp spO = RegExp(r"(([ *_^#`\\])|\\)(\^)(?![ ^])");
  RegExp spC = RegExp(r"(\S)(\^(?=\W|\\))");
  RegExp unO = RegExp(r"(([ *_^#`\\])|\\)(_)(?![ _])");
  RegExp unC = RegExp(r"(\S)(_(?=\W|\\))");
  RegExp ovO = RegExp(r"(([ *_^#`\\])|\\)(___)(?![ _])");
  RegExp ovC = RegExp(r"(\S)(___(?=\W|\\))");
  RegExp stO = RegExp(r"(([ *_^#`\\])|\\)(__)(?![ _])");
  RegExp stC = RegExp(r"(\S)(__(?=\W|\\))");
  RegExp codeO = RegExp(r"(([ *_^#`\\])|\\)(```)(?![ `])");
  RegExp codeC = RegExp(r"(\S)(```(?=\W|\\))");

  // pad the value rather than adding extra cases for start and end of line
  if (value.length > 2) {
    value = " $value ";
  } else {
    return extractStyles(value, []); // There is nothing to apply markdown to
  }

  while (bdO.firstMatch(value) != null &&
      bdC.firstMatch(value) !=
          null) // add or for start and end or add space to start and end
  {
    value =
        value.replaceFirstMapped(bdO, (match) => "${match.group(1)!}###bol###");
    value = value.replaceFirstMapped(bdC, (match) => "${match[1]!}###bol###");
  }

  while (itO.firstMatch(value) != null && itC.firstMatch(value) != null) {
    value =
        value.replaceFirstMapped(itO, (match) => "${match.group(1)!}###ita###");
    value = value.replaceFirstMapped(itC, (match) => "${match[1]!}###ita###");
  }

  while (sbO.firstMatch(value) != null && sbC.firstMatch(value) != null) {
    value =
        value.replaceFirstMapped(sbO, (match) => "${match.group(1)!}###sub###");
    value = value.replaceFirstMapped(sbC, (match) => "${match[1]!}###sub###");
  }

  while (spO.firstMatch(value) != null && spC.firstMatch(value) != null) {
    value =
        value.replaceFirstMapped(spO, (match) => "${match.group(1)!}###sup###");
    value = value.replaceFirstMapped(spC, (match) => "${match[1]!}###sup###");
  }

  while (ovO.firstMatch(value) != null && ovC.firstMatch(value) != null) {
    value =
        value.replaceFirstMapped(ovO, (match) => "${match.group(1)!}###ove###");
    value = value.replaceFirstMapped(ovC, (match) => "${match[1]!}###ove###");
  }

  while (stO.firstMatch(value) != null && stC.firstMatch(value) != null) {
    value =
        value.replaceFirstMapped(stO, (match) => "${match.group(1)!}###str###");
    value = value.replaceFirstMapped(stC, (match) => "${match[1]!}###str###");
  }

  while (unO.firstMatch(value) != null && unC.firstMatch(value) != null) {
    value =
        value.replaceFirstMapped(unO, (match) => "${match.group(1)!}###und###");
    value = value.replaceFirstMapped(unC, (match) => "${match[1]!}###und###");
  }

  while (codeO.firstMatch(value) != null && codeC.firstMatch(value) != null) {
    value = value.replaceFirstMapped(
        codeO, (match) => "${match.group(1)!}###code###");
    value =
        value.replaceFirstMapped(codeC, (match) => "${match[1]!}###code###");
  }

  return extractStyles(value, []);
}