Re: [Question] Custom parse tree filter

[Nicolas Goaziou]

Hello,

Juan Manuel Macías <maciaschain@posteo.net> writes:

> I am writing a custom parse tree filter that does the following (LaTeX
> backend): if a heading has the ':font:' property, the content of that
> heading is enclosed in a LaTeX group. If the property is ':fontfeature:',
> then the content is enclosed in a different group. The filter works fine
> when all the headings are at the same level. But with different levels,
> it does not returns the expected result. It's evident that I'm doing
> something catastrophically wrong :-). I wonder if anyone could put me on
> the track of the origin of my error...
>
> Below, the offender function and a sample. Thanks in advance!

I think you are operating at the wrong level. Higher level headlines
contain lower level ones. I suggest to operate on sections instead.

Also, using `org-element-interpret-data' is meh because you're operating
at the parse tree level. You can insert export-snippet objects directly.

Here's a proposal. This could be refactored, but you get the idea.

--8<---------------cut here---------------start------------->8---
(defun my-custom-filters/fontspec-headline (tree backend info)
  (when (org-export-derived-backend-p backend 'latex)
    (org-element-map tree 'section
      (lambda (section)
        (let ((font (org-export-get-node-property :FONT section t))
              (fontfeature (org-export-get-node-property :FONTFEATURE section 
t))
              (create-export-snippet
               ;; Create "latex" export-snippet with value V.
               (lambda (v)
                 (org-element-create 'export-snippet (list :back-end "latex" 
:value v)))))
          (cond
           (font
            (apply #'org-element-set-contents
                   section
                   (append (list (funcall create-export-snippet "%font 
start\n"))
                           (org-element-contents section)
                           (list (funcall create-export-snippet "%font 
end\n")))))
           (fontfeature
            (apply #'org-element-set-contents
                   section
                   (append (list (funcall create-export-snippet "%fontfeature 
start\n"))
                           (org-element-contents section)
                           (list (funcall create-export-snippet "%fontfeature 
end\n"))))))))
      info)
    tree))
--8<---------------cut here---------------end--------------->8---

Also, when "org-cite-wip" is merged, you will be able to replace, e.g.,

  (funcall create-export-snippet "%fontfeature start\n")

with 

  (org-export-raw-string "%fontfeature start\n")

Regards,
-- 
Nicolas Goaziou