Font lock and filling for Pandoc fancy_lists

From the Pandoc User's Guide

> The `fancy_lists` extension also allows '#' to be used as an ordered
> list marker in place of a numeral:
>
> #. one
> #. two

markdown-mode.el

@@ -1195,7 +1195,7 @@ Group 5 matches the reference label.")
   "Regexp identifying Markdown headers.")
 
 (defconst markdown-regex-header-1-atx
-  "^\\(#\\)[ \t]*\\(.+?\\)[ \t]*\\(#*\\)$"
+  "^\\(#\\)[ \t]*\\([^\\.].*?\\)[ \t]*\\(#*\\)$"
   "Regular expression for level 1 atx-style (hash mark) headers.")
 
 (defconst markdown-regex-header-2-atx
@@ -1259,7 +1259,7 @@ Group 2 matches the key sequence.")
   "Regular expression for matching preformatted text sections.")
 
 (defconst markdown-regex-list
-  "^\\([ \t]*\\)\\([0-9]+\\.\\|[\\*\\+-]\\)\\([ \t]+\\)"
+  "^\\([ \t]*\\)\\([0-9#]+\\.\\|[\\*\\+-]\\)\\([ \t]+\\)"
   "Regular expression for matching list items.")
 
 (defconst markdown-regex-bold
@@ -4681,7 +4681,7 @@ This is an exact copy of `line-number-at-pos' for use in emacs21."
   "Return prefix for filling paragraph or nil if not determined."
   (cond
    ;; List item inside blockquote
-   ((looking-at "^[ \t]*>[ \t]*\\([0-9]+\\.\\|[*+-]\\)[ \t]+")
+   ((looking-at "^[ \t]*>[ \t]*\\(\\(?:[0-9]+\\|#\\)\\.\\|[*+-]\\)[ \t]+")
     (replace-regexp-in-string
      "[0-9\\.*+-]" " " (match-string-no-properties 0)))
    ;; Blockquote
@@ -4789,7 +4789,7 @@ if ARG is omitted or nil."
                     "\f" ; starts with a literal line-feed
                     "[ \t\f]*$" ; space-only line
                     "[ \t]*[*+-][ \t]+" ; unordered list item
-                    "[ \t]*[0-9]+\\.[ \t]+" ; ordered list item
+                    "[ \t]*\\(?:[0-9]+\\|#\\)\\.[ \t]+" ; ordered list item
                     "[ \t]*\\[\\S-*\\]:[ \t]+" ; link ref def
                     )
                   "\\|"))

tests/markdown-test.el

@@ -2593,6 +2593,22 @@ See `paragraph-separate'."
     (markdown-test-range-has-face 24 26 markdown-pre-face)
     (markdown-test-range-has-face 28 30 markdown-pre-face)))
 
+;;; Tests for other extensions:
+
+(ert-deftest test-markdown-ext/pandoc-fancy-lists ()
+  "Test basic support for font lock and filling of Pandoc 'fancy lists'."
+  (markdown-test-string " #. abc\ndef\n"
+    ;; font lock
+    (markdown-test-range-has-face 1 1 nil)
+    (markdown-test-range-has-face 2 3 markdown-list-face)
+    (markdown-test-range-has-face 4 11 nil)
+    ;; filling
+    (forward-line)
+    (markdown-indent-region (line-beginning-position) (line-end-position) nil)
+    (should (string-equal (buffer-string) " #. abc\n def\n"))
+    (markdown-indent-region (line-beginning-position) (line-end-position) nil)
+    (should (string-equal (buffer-string) " #. abc\n    def\n"))))
+
 (provide 'markdown-test)
 
 ;;; markdown-test.el ends here