rStripComments function

Implementation

String rStripComments(String txt) {
  List<String> lines = txt.split('\n');
  List<String> result = [];

  for (int i = 0; i < lines.length; i++) {
    // Keep only those lines that are not comments and not empty.

    if (!lines[i].startsWith('#') && lines[i].isNotEmpty) {
      // Strip comments at the end of the line.

      // Need to be clever to not strip # where # is embedded like in
      //
      // Ecdf(eds[eds$grp=="All",1], col="#E495A5", ...)
      //
      // Or like in
      //
      // title <- glue("Risk Chart &#8212; {mdesc}")
      //
      // Use a pattern with a negative lookbehind assertion (?<!\") which
      // ensures that the # is not preceded by a ".

      result.add(lines[i].replaceAll(RegExp(r' *(?<!\".*)#.*'), ''));
    }
  }

  // Remove empty lines on joining.

  String compressed = result.where((line) => line.trim().isNotEmpty).join('\n');

  // Add newlines at the beginning and the end to ensure the commands are on
  // lines of their own.

  return '\n$compressed\n';
}