up method

bool up()

Moves to the line above, keeping the column. False on the first line.

Implementation

bool up() {
  final start = _lineStart(_cursor);
  if (start == 0) {
    return false;
  }
  final column = _cursor - start;
  final previousStart = _lineStart(start - 1);
  _cursor = previousStart + _min(column, start - 1 - previousStart);
  return true;
}