Re: Expose value-begin and value-end instead of just value in org-element API

[Nicolas Goaziou <mail@nicolasgoaziou.fr>]

Hello,

John Kitchin <jkitchin@andrew.cmu.edu> writes:

> +1 on this.
>
> I also have some janky code to do things like go to the beginning/end of
> the value in a src block. Here is my solution to mark the code in a src
> block.
>
> (defun ob-ipython-mark-code ()
>   "Mark the code in the block."
>   (interactive)
>   (org-edit-special)
>   (let ((p0 (point-min))
> (p1 (point-max)))
>     (goto-char p0)
>     (org-edit-src-exit)
>     (set-mark (point))
>     (goto-char (+ (point) (- p1 2)))))

You get the beginning of the code of a source block with

  (org-with-point-at (org-element-property :post-affiliated element)
    (line-beginning-position 2))

and its end with

  (org-with-point-at (org-element-property :end element)
    (line-beginning-position (- (org-element-property :post-blank element))))

From there, you can easily construct something that doesn't rely on
`org-edit-special'.

>> I think it would be preferable to also expose the value by beginning and
>> ending buffer positions for the following reasons:
>> - Consistency with elements that expose contents-begin and contents-end.

The point is terminal elements are not consistent with non-terminal
ones, and should not be.

>> - More powerful. In my evil-org plugin I want to be able to mark the value
>> property of the org element at point (so the user can do stuff like easily
>> copy the code of the current code block), but to do so I need the beginning
>> and ending position in the buffer of "value". The org-element API does
>> currently not provide clean way to retrieve these positions.

See above. It is quite simple to extract this information from the parse
tree.

>> - It's usually more efficient to return the beginning and ending positions
>> than to retrieve the substring that contains the value, which may require a
>> large buffer partition to be copied.

Efficiency is a moot point because you still need to store the value of
the block. If you remove it, the parse tree is no longer an equivalent
representation of the document.

Regards,

-- 
Nicolas Goaziou