Improving org-block-begin-line, splitting in several faces

Question

The face org-block-begin-line allows to customize the first line of the following block

#+BEGIN_SRC lang :var arg1=1 arg2=2
...
#+END_SRC

However, I would like to customize the faces within the line, by highlighting the lang, and certain properties, like highlighting only arg2=2.

Digging further, we can see that the use of the face is done within (org-fontify-meta-lines-and-blocks-1). But nothing there seems to allow to split the line in several blocks, and even less by doing it conditionally.

Something similar was proposed by rasmus ( https://pank.eu/blog/pretty-babel-src-blocks.html ) to implement further modification on the line, but this is not quite what I am looking for.

Might there be a package already available out there to add some colors // apply some regexp on this line ?

Also, it might be interesting if the same rules could apply on an inline src_lang() and a #+CALL: type of line.

Answer 1

I am not a fan on my approach, but I ended up redefining (org-fontify-meta-lines-and-blocks-1). I am posting the idea here :

(defun org-fontify-meta-lines-and-blocks-1 (limit)
  "Fontify #+ lines and blocks."
  (let ((case-fold-search t))
    (when (re-search-forward
       "^\\([ \t]*#\\(\\(\\+[a-zA-Z]+:?\\| \\|$\\)\\(_\\([a-zA-Z]+\\)\\)?\\)[ \t]*\\(\\([^ \t\n]*\\)[ \t]*\\(.*\\)\\)\\)"
       limit t)
      (let ((beg (match-beginning 0))
        (block-start (match-end 0))
        (block-end nil)
        (lang (match-string 7))
        ;; -- Aurix addon --
        (beglang (match-beginning 7))
        (endlang (match-end 7))
        (meta (match-string 8))
        (begmeta (match-beginning 8))
        ;; -----------------

        ;; ...

        ;; -- Aurix addon --
        (when (equal lang "my-lang")
            (add-text-properties beglang endlang '(face my-lang-face))
            (when (string-match ":var[ \t]+arg1=\"\\([^\"]+\\)\"" meta)
                (let ((begt (+ begmeta (match-beginning 1))) (endt (+ begmeta (match-end 1))))
                    (add-text-properties begt endt '(face my-arg1-face))
                )
            )
            ;; ...
        )
        ;; -----------------
        t)) 
        ;; ...
))))