Implement 'Default' for 'ChessBoard'

src/board/chess_board.rs

@@ -272,6 +272,42 @@ impl ChessBoard {
     }
 }
 
+/// Use the starting position as a default value, corresponding to the
+/// "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1" FEN string
+impl Default for ChessBoard {
+    fn default() -> Self {
+        Self {
+            piece_occupancy: [
+                // King
+                Square::E1 | Square::E8,
+                // Queen
+                Square::D1 | Square::D8,
+                // Rook
+                Square::A1 | Square::A8 | Square::H1 | Square::H8,
+                // Bishop
+                Square::C1 | Square::C8 | Square::F1 | Square::F8,
+                // Knight
+                Square::B1 | Square::B8 | Square::G1 | Square::G8,
+                // Pawn
+                Rank::Second.into_bitboard() | Rank::Seventh.into_bitboard(),
+            ],
+            color_occupancy: [
+                Rank::First.into_bitboard() | Rank::Second.into_bitboard(),
+                Rank::Seventh.into_bitboard() | Rank::Eighth.into_bitboard(),
+            ],
+            combined_occupancy: Rank::First.into_bitboard()
+                | Rank::Second.into_bitboard()
+                | Rank::Seventh.into_bitboard()
+                | Rank::Eighth.into_bitboard(),
+            castle_rights: [CastleRights::BothSides; 2],
+            en_passant: None,
+            half_move_clock: 0,
+            total_plies: 0,
+            side: Color::White,
+        }
+    }
+}
+
 /// Return a [ChessBoard] from the given FEN string.
 impl FromFen for ChessBoard {
     type Err = Error;