add pygn-mode--pgn-at-pos-or-stub

a forgiving version of pygn-mode-pgn-at-pos, which always returns a
valid PGN, even a made-up one

Author: rolandwalker

pygn-mode.el

@@ -1200,6 +1200,14 @@ garbage."
        start-pos
        (point)))))
 
+(defun pygn-mode--pgn-at-pos-or-stub (pos)
+  "Return a single-game PGN string inclusive of any move at POS.
+
+Identical to `pygn-mode-pgn-at-pos' except that a stub value is returned
+when POS is not inside a game."
+  (or (pygn-mode-pgn-at-pos pos)
+      "[Event \"?\"]\n\n*\n"))
+
 (defun pygn-mode-pgn-at-pos-as-if-variation (pos)
   "Return a single-game PGN string as if a variation had been played.
 
@@ -1779,7 +1787,7 @@ When called non-interactively, display the FEN corresponding to POS.
 With `prefix-arg' DO-COPY, copy the FEN to the kill ring, and to the system
 clipboard when running a GUI Emacs."
   (interactive "d\nP")
-  (let ((fen (pygn-mode-pgn-to-fen (pygn-mode-pgn-at-pos pos))))
+  (let ((fen (pygn-mode-pgn-to-fen (pygn-mode--pgn-at-pos-or-stub pos))))
     (when do-copy
       (kill-new fen)
       (when (and (fboundp 'gui-set-selection)
@@ -1798,7 +1806,7 @@ clipboard when running a GUI Emacs."
 
 When called non-interactively, display the FEN corresponding to POS."
   (interactive "d")
-  (let* ((fen (pygn-mode-pgn-to-fen (pygn-mode-pgn-at-pos pos)))
+  (let* ((fen (pygn-mode-pgn-to-fen (pygn-mode--pgn-at-pos-or-stub pos)))
          (buf (get-buffer-create pygn-mode-fen-buffer-name))
          (win (get-buffer-window buf)))
     (with-current-buffer buf
@@ -1829,7 +1837,7 @@ When called non-interactively, display the FEN corresponding to POS."
   "Save the board image corresponding to POS to a file."
   (let* ((pygn-mode-board-size (completing-read "Pixels per side: " nil nil nil nil nil pygn-mode-board-size))
          (filename (read-file-name "SVG filename: "))
-         (svg-data (pygn-mode-pgn-to-board (pygn-mode-pgn-at-pos pos) 'svg)))
+         (svg-data (pygn-mode-pgn-to-board (pygn-mode--pgn-at-pos-or-stub pos) 'svg)))
     (with-temp-buffer
       (insert svg-data)
       (write-file filename))))
@@ -1839,7 +1847,7 @@ When called non-interactively, display the FEN corresponding to POS."
 
 When called non-interactively, display the board corresponding to POS."
   (interactive "d")
-  (let* ((svg-data (pygn-mode-pgn-to-board (pygn-mode-pgn-at-pos pos) 'svg))
+  (let* ((svg-data (pygn-mode-pgn-to-board (pygn-mode--pgn-at-pos-or-stub pos) 'svg))
          (buf (pygn-mode--get-or-create-board-buffer))
          (win (get-buffer-window buf)))
     (with-current-buffer buf
@@ -1858,7 +1866,7 @@ When called non-interactively, display the board corresponding to POS."
 
 When called non-interactively, display the board corresponding to POS."
   (interactive "d")
-  (let* ((text-data (pygn-mode-pgn-to-board (pygn-mode-pgn-at-pos pos) 'text))
+  (let* ((text-data (pygn-mode-pgn-to-board (pygn-mode--pgn-at-pos-or-stub pos) 'text))
          (buf (pygn-mode--get-or-create-board-buffer))
          (win (get-buffer-window buf)))
     (with-current-buffer buf
@@ -1931,7 +1939,7 @@ When called non-interactively, display the board corresponding to POS."
 
 When called non-interactively, display the line corresponding to POS."
   (interactive "d")
-  (let* ((line (pygn-mode-pgn-to-line (pygn-mode-pgn-at-pos pos)))
+  (let* ((line (pygn-mode-pgn-to-line (pygn-mode--pgn-at-pos-or-stub pos)))
          (buf (get-buffer-create pygn-mode-line-buffer-name))
          (win (get-buffer-window buf)))
     (with-current-buffer buf