tokenizeWithNewLines function

List<String> tokenizeWithNewLines(String str)

Splits a string str by new line characters ("\n"), preserving empty lines as separate tokens in the resulting array.

Example:

String input = "hello\n\nworld\n ";
List<String> tokens = tokenizeWithNewLines(input);
print(tokens); // Output: ["hello", "\n", "\n", "world", "\n", " "]

Returns a list of strings where each element represents either a line of text or a new line character.

Implementation

List<String> tokenizeWithNewLines(String str) {
  const String newLine = '\n';

  if (str == newLine) {
    return <String>[str];
  }

  List<String> lines = str.split(newLine);

  if (lines.length == 1) {
    return lines;
  }

  int lastIndex = lines.length - 1;

  return lines.foldIndexed(<String>[], (int ind, List<String> pv, String line) {
    if (ind != lastIndex) {
      if (line != '') {
        pv.add(line);
        pv.add(newLine);
      } else {
        pv.add(newLine);
      }
    } else if (line != '') {
      pv.add(line);
    }
    return pv;
  });
}