togglecomment.vim

" Reference: https://stackoverflow.com/a/24652257/2571881

" TODO: Reselect visual mode
" OBS: I was using --> exec 'normal! _"_2x' 
" How to know if I have the optional space after the comment '[ ]?' ?
" because this influences the cursor position

" Now all comments are added at the beginning of line because other people want 
" to uncomment and comment using visual block
" after that I should give some suggestions to [mike](https://stackoverflow.com/users/2839380/mike) at stackoverflow
" his post on this question [here](https://stackoverflow.com/a/24652257/2571881)

" idea to avoid many ifs
" let l:space = ( &ft =~ "\v(c|cpp|java|arduino)" ? "3" : "2" )


autocmd FileType c,cpp,java      let b:comment_leader = '//'
autocmd FileType arduino         let b:comment_leader = '//'
autocmd FileType sh,ruby,python  let b:comment_leader = '#'
autocmd FileType zsh             let b:comment_leader = '#'
autocmd FileType conf,fstab      let b:comment_leader = '#'
autocmd FileType matlab,tex      let b:comment_leader = '%'
autocmd FileType vim             let b:comment_leader = '"'

function! ToggleComment()
    if exists('b:comment_leader')
        let l:pos = col('.')
        let l:space = ( &ft =~ '\v(c|cpp|java|arduino)' ? '3' : '2' )
        if getline('.') =~ '\v(\s*|\t*)' .b:comment_leader
            let l:space -= ( getline('.') =~ '\v.*\zs' . b:comment_leader . '(\s+|\t+)@!' ?  1 : 0 )
            execute 'silent s,\v^(\s*|\t*)\zs' .b:comment_leader.'[ ]?,,g'
            let l:pos -= l:space
        else
            exec 'normal! 0i' .b:comment_leader .' '
            let l:pos += l:space
        endif
        call cursor(line("."), l:pos)
    else
        echo 'no comment leader found for filetype'
    end
endfunction

nnoremap <Leader>t :call ToggleComment()<CR>
inoremap <Leader>t <C-o>:call ToggleComment()<CR>
xnoremap <Leader>t :'<,'>call ToggleComment()<CR>