parseSquare function

Square? parseSquare(
  1. String str
)

Parses a string like 'a1', 'a2', etc. and returns a Square or null if the square doesn't exist.

Implementation

Square? parseSquare(String str) {
  if (str.length != 2) return null;
  final file = str.codeUnitAt(0) - 'a'.codeUnitAt(0);
  final rank = str.codeUnitAt(1) - '1'.codeUnitAt(0);
  if (file < 0 || file >= 8 || rank < 0 || rank >= 8) return null;
  return file + 8 * rank;
}