Feature request: Support for Pandoc Markdown's inline footnotes

[zmwangx]

The syntax of Pandoc Markdown's inline footnotes, per manual, is

Here is an inline note.^[Inlines notes are easier to write, since
you don't have to pick an identifier and move down to type the
note.]

Would you consider supporting this syntax? A quick patch to enable this would be

diff --git a/markdown-mode.el b/markdown-mode.el
index 524b311..b760f58 100644
--- a/markdown-mode.el
+++ b/markdown-mode.el
@@ -1173,6 +1173,13 @@ Group 1 matches the opening square bracket and carat.
 Group 2 matches only the label, without the surrounding markup.
 Group 3 matches the closing square bracket.")

+(defconst markdown-regex-inline-footnote
+  "\\(\\^\\[\\)\\([^]]+\\)\\(\\]\\)"
+  "Regular expression for an inline footnote ^[footnote text].
+Group 1 matches the opening caret and square bracket.
+Group 2 matches the footnote text, without the surrounding markup.
+Group 3 matches the closing square bracket.")
+
 (defconst markdown-regex-header
   "^\\(?:\\(.+\\)\n\\(=+\\)\\|\\(.+\\)\n\\(-+\\)\\|\\(#+\\)\\s-*\\(.*?\\)\\s-*?\\(#*\\)\\)$"
   "Regexp identifying Markdown headings.
@@ -1886,6 +1893,9 @@ See `font-lock-syntactic-face-function' for details."
    (cons markdown-regex-footnote '((1 markdown-markup-face)   ; [^
                                    (2 markdown-footnote-face) ; label
                                    (3 markdown-markup-face))) ; ]
+   (cons markdown-regex-inline-footnote '((1 markdown-markup-face)   ; ^[
+                                          (2 markdown-footnote-face) ; footnote text
+                                          (3 markdown-markup-face))) ; ]
    (cons markdown-regex-link-inline '((1 markdown-markup-face nil t)     ; ! (optional)
                                       (2 markdown-markup-face)           ; [
                                       (3 markdown-link-face)             ; text

I haven't considered if there would be any undesirable side effects.

[jrblevin]

Thanks--I'll definitely consider it.

[zmwangx]

Hmm, just noticed that my regex didn't match linefeeds in footnote texts, so it didn't even pass the example above... The regex is now corrected in the original post.

[syohex]

You can highlight by font-lock-add-keywords as bellow.

(font-lock-add-keywords
 'markdown-mode
 '(("\\(\\^\\[\\)\\([^]]+\\)\\(\\]\\)"
    (1 'markdown-markup-face)
    (2 'markdown-footnote-face)
    (3 'markdown-markup-face))))

I'm not sure it is better to support such markdown dialect. Because there are many markdown dialects.

[zmwangx]

You can highlight by font-lock-add-keywords as bellow.

Why? My patch already does highlighting.

I'm not sure it is better to support such markdown dialect. Because there are many markdown dialects.

I'm not sure either, that's why I asked "would you consider supporting this syntax?". Bottom line: Pandoc is a popular dialect, and markdown-mode already supports some Pandoc-specific features (as well as features from other dialects, e.g., multimarkdown). Those are reasons why I'm even mentioning this.

Update. Actually there's another reason: it doesn't hurt. ^[text] is very uncommon in regular prose, so there's no surprise.

[syohex]

Why? My patch already does highlighting.

As I said, I'm not sure to implement this feature into markdown-mode. My snippet is highlight pandoc inline footnote syntax without changing markdown-mode code(You can highlight by putting it your init.el).

[jrblevin]

Thanks for this suggestion. We now have support for inline footnotes (7499d28), with raised text and optionally hidden markup (669815e).