" provide <Plug> mappings for easy remapping

nnoremap <silent> <Plug>(Visual-Split-Resize) :<C-u>set operatorfunc=<SID>opgr<CR>g@

nnoremap <silent> <Plug>(Visual-Split-Split) :<C-u>set operatorfunc=<SID>opgss<CR>g@

nnoremap <silent> <Plug>(Visual-Split-SplitAbove) :<C-u>set operatorfunc=<SID>opgsa<CR>g@

nnoremap <silent> <Plug>(Visual-Split-SplitBelow) :<C-u>set operatorfunc=<SID>opgsb<CR>g@

" normal mode mappings set operator functions

" TODO: make these silent?

silent! nmap <unique> <C-W>gr <Plug>(Visual-Split-Resize)

silent! nmap <unique> <C-W>gss <Plug>(Visual-Split-Split)

silent! nmap <unique> <C-W>gsa <Plug>(Visual-Split-SplitAbove)

silent! nmap <unique> <C-W>gsb <Plug>(Visual-Split-SplitBelow)

" operator functions trigger visual mappings

function! s:opgr(type, ...)

call s:op("gr")

endfunction

function! s:opgss(type, ...)

call s:op("gss")

endfunction

function! s:opgsa(type, ...)

call s:op("gsa")

endfunction

function! s:opgsb(type, ...)

call s:op("gsb")

endfunction

function! s:op(trigger)

silent execute "normal! '[V']"

silent execute "normal \<C-W>" . a:trigger

endfunction

" provide <Plug> mappings for easy remapping

xnoremap <silent> <Plug>(Visual-Split-VSResize) :VSResize<CR>

xnoremap <silent> <Plug>(Visual-Split-VSSplit) :VSSplit<CR>

xnoremap <silent> <Plug>(Visual-Split-VSSplitAbove) :VSSplitAbove<CR>

xnoremap <silent> <Plug>(Visual-Split-VSSplitBelow) :VSSplitBelow<CR>

" visual mappings execute commands

silent! xmap <unique> <C-W>gr <Plug>(Visual-Split-VSResize)

silent! xmap <unique> <C-W>gss <Plug>(Visual-Split-VSSplit)

silent! xmap <unique> <C-W>gsa <Plug>(Visual-Split-VSSplitAbove)

silent! xmap <unique> <C-W>gsb <Plug>(Visual-Split-VSSplitBelow)

" commands call functions

command! -range VSResize call <SID>resize(<line1>, <line2>)

command! -range VSSplit call <SID>split("", <line1>, <line2>)

command! -range VSSplitAbove call <SID>split("above", <line1>, <line2>)

command! -range VSSplitBelow call <SID>split("below", <line1>, <line2>)

" functions execute wincmds

function! s:resize(line1, line2)

if s:single()

return

endif

execute s:lines_between(a:line1, a:line2) . "wincmd _"

call s:scroll(a:line1)

endfunction

function! s:split(position, line1, line2)

execute a:position . s:lines_between(a:line1, a:line2) . "wincmd s"

call s:scroll(a:line1)

wincmd p

endfunction

function! s:lines_between(line1, line2)

if &wrap

" Calculate the number of visibly selected lines, which may be more

" than the number of actual selected lines.

return s:visual_lines_between(a:line1, a:line2)

else

" The number of selected lines is a simple calculation.

return a:line2 - a:line1 + 1

endif

endfunction

function! s:visual_lines_between(line1, line2)

call cursor(a:line1, 0)

let l:visual_lines = 0

let l:previous_line = line('.')

let l:previous_col = col('.')

" Count lines until reach a:line2, or have counted up to lines that can be

" displayed in this Vim instance (no point counting beyond this as can't

" resize window larger than this, and can seriously harm performance).

while line('.') <= a:line2 && l:visual_lines < &lines

normal! gj

let l:visual_lines += 1

if line('.') == l:previous_line && col('.') == l:previous_col

" We haven't moved from our previous position, so must be on the

" last visual line. We need to break out now since we're never

" going to reach a:line2 and would loop indefinitely.

break

endif

let l:previous_line = line('.')

let l:previous_col = col('.')

endwhile

" Move to back to first row and column of selection.

call cursor(a:line1, 1)

return l:visual_lines

endfunction

function! s:scroll(line)

let scrolloff = &scrolloff

let &scrolloff = 0

call cursor(a:line, 0)

normal! ztM

let &scrolloff=scrolloff

endfunction

function! s:single()

" Remember current previous window, as will be overwritten by process of

" determining if this is a singular window and we will need to reset it.

wincmd p

let previous_winnr = winnr()

wincmd p

" remember original window

let winnr = winnr()

wincmd k " try to move up

if winnr() != winnr " found window above

wincmd p " Move back to original window.

call s:reset_previous_window(previous_winnr)

return 0

endif

wincmd j " try to move down

if winnr() != winnr " found window below

wincmd p " Move back to original window.

call s:reset_previous_window(previous_winnr)

return 0

endif

return 1

endfunction

function! s:reset_previous_window(previous_winnr)

" Switch to remembered window and back again to reset previous window to

" what it was before we overwrote it.

execute a:previous_winnr.'wincmd w'

wincmd p

endfunction