Find first occurrence of string or return end of file

Question

I am currently setting up my Vim to work with matlab. In matlab, sections are separated by %%, and I am looking for a command to select my current section.

I currently use

nnoremap <Leader>f mf:?%%<CR><Down>v/%%<CR><Up>$:SlimuxREPLSendSelection<CR>`f

to mark the current position as f, search upwards for %%, and select to the next occurrence of %%. The selection is then send to the matlab terminal via Slimux and then I go back to mark f.

However, I would like to extend this to the case when there is no %% before the cursor (then vim should go to the beginning of the file) or when there is no %% after the cursor (then vim should go to the end of the file).

Thank you.

EDIT

The solution by Tumbler41 almost worked for me, I had to change it a tiny bit because the Slimux function call wouldn't work and to make it able to cope when the cursor is on %%.

nnoremap <Leader>f :call SendSection()<CR>:SlimuxREPLSendSelection<CR>`f

function! SendSection()
   normal! mf
   if (search('%%', 'b') <= line("'f"))
      normal! jV
   else
      normal! ggV
   endif
   if (search('%%') > line("'f"))
      normal! k
   else
      normal! G
   endif
endfunction

Answer 1

Try this:

nnoremap <Leader>f :call SendSection()<CR>

function! SendSection()
   normal! mf
   let firstLine = search('%%', 'b')
   if (firstLine != 0 && firstLine <= line("'f"))
      normal! jV
   else
      normal! ggV
   endif
   if (search('%%') > line("'f"))
      normal! k
   else
      normal! G
   endif
   '<,'>SlimuxREPLSendSelection
   normal! `f
endfunction

Note: I don't have Slimux and therefore can't test that part.

I'm using search() to find out if there is a %% before and after the mark f.

Answer 2

Assuming you are using the slimux you can use :SlimuxREPLSendLine with a line range. \%^ and \%$ mark the start and end of the file respectively. Combine these regex anchors with a pattern alternation (\|), we can search for %% or one of the anchors.

nnoremap <leader>f mf:+?\(%%\n\zs\<bar>\%^\)?,-/\(\zs\n%%\<bar>\%$\)/SlimuxREPLSendLine<cr>`f

Note: Due to how trickiness of the range, this mapping will not work when you are on a %%.

To take this further you may want to may want to look into vim-textobj-user. Here is a quick and dirty text objects:

xnoremap i% :<c-u>call search('\(%%\<bar>\%^\)\_s*\zs.', 'cbW')<cr>m<:call search('.\ze\_s*\(%%\<bar>\%$\)', 'We')<cr>m>gv
onoremap i% :normal vi%<cr>

Now you can use i% text object. Now we can pair it with the a new mapping which uses this text object:

nmap <leader>f mfvi%:SlimuxREPLSendSelection<cr>`m

For more help see:

:h :range
:h /\|
:h /\zs
:h /\%^
:h /\%$
:h search(