diff options
Diffstat (limited to 'chess-fen.el')
| -rw-r--r-- | chess-fen.el | 38 |
1 files changed, 24 insertions, 14 deletions
diff --git a/chess-fen.el b/chess-fen.el index c372dc2..aa4ffd3 100644 --- a/chess-fen.el +++ b/chess-fen.el @@ -23,8 +23,8 @@ ;; ;; The FLAGS can contain K, Q, k or q, to signify whether the white or ;; black king can still castle on the king or queen side. You can -;; also have coordinates, such as e4, a5, to specify which pawns may -;; be captured by en passant. +;; also have coordinates, such as e3, a6, to specify the target sqaure +;; of an en passant capture. ;; ;; The starting chess position always looks like this: ;; @@ -77,8 +77,12 @@ ((= c ?k) (chess-pos-set-can-castle position ?k t)) ((= c ?q) (chess-pos-set-can-castle position ?q t)) ((and (>= c ?a) (<= c ?h)) - (chess-pos-set-en-passant position (chess-coord-to-index - (substring fen i (+ i 2)))) + (chess-pos-set-en-passant + position + (let ((target (chess-coord-to-index (substring fen i (+ i 2))))) + (chess-incr-index target (if (= (chess-index-rank target) 2) + 1 (if (= (chess-index-rank target) 5) + -1 (setq error t) 0)) 0))) (setq i (1+ i))) (t (setq error t))) @@ -105,20 +109,26 @@ If FULL is non-nil, represent trailing spaces as well." (setq str (if (chess-pos-side-to-move position) (concat str " w ") (concat str " b "))) - (if (chess-pos-can-castle position ?K) - (setq str (concat str "K") output t)) - (if (chess-pos-can-castle position ?Q) - (setq str (concat str "Q") output t)) - (if (chess-pos-can-castle position ?k) - (setq str (concat str "k") output t)) - (if (chess-pos-can-castle position ?q) - (setq str (concat str "q") output t)) + (mapc (lambda (castle) + (if (chess-pos-can-castle position castle) + (setq str (concat str (string castle)) output t))) + '(?K ?Q ?k ?q)) (if output (setq str (concat str " ")) (setq str (concat str "- "))) (let ((index (chess-pos-en-passant position))) - (if index - (concat str (chess-index-to-coord index)) + (if (and index + (let ((pawn (if (chess-pos-side-to-move position) ?P ?p))) + (or (and (chess-incr-index index 0 -1) + (eq (chess-pos-piece position (chess-incr-index + index 0 -1)) pawn)) + (and (chess-incr-index index 0 1) + (eq (chess-pos-piece position (chess-incr-index + index 0 1)) pawn))))) + (concat str (chess-index-to-coord + (if (chess-pos-side-to-move position) + (chess-incr-index index -1 0) + (chess-incr-index index 1 0)))) (concat str "-"))))) (provide 'chess-fen) |