added helper method for fen parsing to utils.rs

engine/src/bitboard/utils.rs

@@ -27,6 +27,27 @@ pub fn notation_from_square_number(sq: u8) -> String {
   return notation;
 }
 
+pub fn try_get_square_number_from_notation(notation: &str) -> Result<u8, ()> {
+
+  let file = match notation.chars().nth(0).unwrap() {
+    'a' => 0,
+    'b' => 1,
+    'c' => 2,
+    'd' => 3,
+    'e' => 4,
+    'f' => 5,
+    'g' => 6,
+    'h' => 7,
+     _  => { return Result::Err(()); }
+  };
+  if let Some(rank) = notation.chars().nth(1) {
+    return Result::Ok(file + 8 * (rank.to_digit(10).unwrap() as u8) - 8);
+  }
+  else {
+    return Result::Err(());
+  }
+}
+
 
 // <----- TESTS ----->