fold text in bib files?

[yongrenjie]

Is your feature request related to a problem? Please describe it.

Setting foldmethod=syntax in bib files (provided by vim8.2's built in syntax file) gives nice folding, but the default fold text is a bit dull. For example (stealing a paper from my supervisor :-))

@article{Foroozandeh2014ACIE,
    doi = {10.1002/anie.201404111},
    author = {Foroozandeh, Mohammadali and Adams, Ralph W. and Meharry, Nicola J. and Jeannerat, Damien and Nilsson, Mathias and Morris, Gareth A.},
    title = {Ultrahigh-Resolution NMR Spectroscopy},
    journaltitle = {Angew.\ Chem.\ Int.\ Ed.},
    year = {2014},
    volume = {53},
    number = {27},
    pages = {6990--6992},
}

produces the following foldtext

+-- 10 lines: @article{Foroozandeh2014ACIE,-----------------------------------------------

IMO, it's not useful to know how many lines an entry is; also, the remainder of the space could be more usefully utilised to show some information about the bib entry.

Describe the solution you'd like

For most bib entries I think the most useful piece of extra information would be the title (?) or for @set{...}, it would be useful to see which entries are contained within the set.

I actually have an implementation of the foldtext function here: https://github.com/yongrenjie/abbotsbury.vim/blob/master/ftplugin/bib.vim which I use personally. For the same bib entry above it produces the following foldtext:

+-- article{Foroozandeh2014ACIE} -- Ultrahigh-Resolution NMR Spectroscopy ----------------

Describe alternatives you've considered

I mainly opened this issue as I was curious as to whether this would be something you might be interested in including in vimtex. I'm happy to modify the output slightly if desired!

The main alternative would be sticking with the default, I guess. There might be an argument that long fold texts lead to visual clutter.

[lervag]

I mainly opened this issue as I was curious as to whether this would be something you might be interested in including in vimtex. I'm happy to modify the output slightly if desired!

I don't quite see why not to add this. I think improving the fold text for bib files should generally be a good thing for most people, and it seems relevant to VimTeX. If it would be opinionated, then we could easily make it optional.

Do you want to open a PR for this? I could add this based on your implementation myself, but if you feel adventurous and want to keep your name on the contribution, then I wouldn't mind helping you with a PR.

[yongrenjie]

I don't mind trying to put a PR together! Before I start, let me consult you about the strategy...

• I guess the foldtext function could go into a new file like autoload/vimtex/fold/bib.vim.
• I could modify the vimtex#fold#init function to check for &filetype. (and remove 'fold' from the disabled modules for bib files).

vimtex/autoload/vimtex/fold.vim

Lines 7 to 15 in fef77c8

	function! vimtex#fold#init_buffer() abort " {{{1
	if !g:vimtex_fold_enabled
	\ || s:foldmethod_in_modeline() | return | endif
	" Set fold options
	setlocal foldmethod=expr
	setlocal foldexpr=vimtex#fold#level(v:lnum)
	setlocal foldtext=vimtex#fold#text()

• Do you think we should have another option like g:vimtex_fold_bib_enabled, defaulting to 1?

[lervag]

I don't mind trying to put a PR together! Before I start, let me consult you about the strategy...

Ah, yes, I can see how it is somewhat confusing how to integrate this in the current init flow. The code did not really consider bib files, so bib file support is sort of "hackish".

My suggestion would be to make it simple, something like this:

1. Add minimal init code here:

   vimtex/autoload/vimtex.vim

   Lines 84 to 92 in fef77c8

   	elseif &filetype ==# 'bib'
   	setlocal suffixesadd=.tex,.bib
   	" Several additional modules should be disabled in bib files
   	let l:disabled_modules += [
   	\ 'fold', 'matchparen', 'format', 'doc', 'imaps', 'cmd', 'delim',
   	\ 'env', 'motion', 'complete',
   	\]
   	endif

   Something like this:

   if g:vimtex_fold_bib_enabled
     setlocal foldmethod=syntax
     setlocal foldtext=vimtex#fold#bib#text()
   endif

2. Add the bibtex foldtext function as vimtex#fold#bib#text() in autoload/vimtex/fold/bib.vim.

3. Add some related words in the docs (under :help vimtex-folding and document the option).

This would keep the main new code separated from other unrelated code, which I think is good. Then I might do some code maintenance and restructuring afterwards.

Does this make sense to you?

[yongrenjie]

Closed by #2066!

[lervag]

I forgot about this issue; thanks for remembering and closing it! :)