Skip leading punctuation when sentence casing titles

citeproc-s.el

@@ -151,12 +151,12 @@ first word is not in lowercase then return S."
 	(buffer-string))
     s))
 
-(defun citeproc-s-sentence-case-title (s omit-nocase)
+(defun citeproc-s-sentence-case-title (s &optional omit-nocase)
   "Return a sentence-cased version of title string S.
 If optional OMIT-NOCASE is non-nil then omit the nocase tags from the output."
   (if (s-blank-p s) s
     (let ((sliced (citeproc-s-slice-by-matches
-		   s "\\(<span class=\"nocase\">\\|</span>\\|: +\\w\\)"))
+		   s "\\(<span class=\"nocase\">\\|</span>\\|: +[[:punct:]]*[[:alpha:]]\\)"))
 	  (protect-level 0)
 	  (first t)
 	  result)
@@ -165,13 +165,18 @@ If optional OMIT-NOCASE is non-nil then omit the nocase tags from the output."
 	 (pcase slice
 	   ("<span class=\"nocase\">" (cl-incf protect-level) (if omit-nocase nil slice))
 	   ("</span>" (cl-decf protect-level) (if omit-nocase nil slice))
-	   ;; Don't touch the first letter after a colon since it is probably a subtitle.
-	   ((pred (string-match-p "^:")) slice)
+	   ;; Don't touch the first letter after a colon since it probably
+	   ;; starts a subtitle.
+	   ((pred (string-match-p "^: +[[:punct:]]*[[:alpha:]]")) (setq first nil) slice)
 	   (_ (cond ((< 0 protect-level) (setq first nil) slice)
 		    ((not first) (downcase slice))
 		    (t (setq first nil)
-		       (concat (upcase (substring slice 0 1))
-			       (downcase (substring slice 1)))))))
+		       ;; We upcase the first letter and downcase the rest.
+		       (let ((pos (string-match "[[:alpha:]]" slice)))
+			 (if pos (concat (substring slice 0 pos)
+					 (upcase (substring slice pos (1+ pos)))
+					 (downcase (substring slice (1+ pos))))
+			   slice))))))
 	 result))
       (apply #'concat (nreverse result)))))