RFE: (better) support for grid tables

[sphakka]

Emacs-style "grid tables" are well supported by Pandoc. However markdown mode doesn't like them that much.

Expected Behavior

Grid table above are rendered wholly in markdown-table-face and are properly aligned by command markdown-table-align.

Actual Behavior

First problem, grid tables are rendered with mixed faces:

• markdown-table-face for the contents
• default face for the grid

Second problem, markdown-table-align doesn't work.

I'd be content of at least having them properly aligned, though full support would be best in the long term.

Steps to Reproduce

Take the Pandoc example as MWE:

+---------------+---------------+--------------------+
| Fruit         | Price         | Advantages         |
+===============+===============+====================+
| Bananas       | $1.34         | - built-in wrapper |
|               |               | - bright color     |
+---------------+---------------+--------------------+
| Oranges       | $2.10         | - cures scurvy     |
|               |               | - tasty            |
+---------------+---------------+--------------------+

• Move the cursor on any grid line and run M-X describe-face. Result:

Face: default (sample) (customize this face)

Documentation:
Basic default face.

Defined in ‘faces.el’.
...

• Move the cursor on any content line and run M-X describe-face. Result:

Face: markdown-table-face (sample) (customize this face)

Documentation:
Face for tables.
...

• Move the cursor on any grid line and run M-X markdown-table-align. Result: the following line is screwed. F.i., on the first one it gives:

+---------------+---------------+--------------------+
| +---------------+---------------+--------------------+ |

• Move the cursor on any content line and run M-X markdown-table-align. Result: only the "pipe-styled" part is aligned. The remainder of the table is ignored.

Software Versions

• Markdown Mode: version 2.7-alpha
• Emacs: GNU Emacs 29.4 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.41, cairo version 1.18.0) of 2024-08-02
• OS: GNU/Linux Gentoo