Vim rotating lines "screensaver"

rotate_lines.vim

" Press \r to start rotating lines and <C-c> (Control+c) to stop.

function! s:RotateString(string)
    let split_string = split(a:string, '\zs')
    return join(split_string[-1:] + split_string[:-2], '')
endfunction

function! s:RotateLine(line, leading_whitespace, trailing_whitespace)
    return substitute(
        \ a:line,
        \ '^\(' . a:leading_whitespace . '\)\(.\{-}\)\(' . a:trailing_whitespace . '\)$',
        \ '\=submatch(1) . <SID>RotateString(submatch(2)) . submatch(3)',
        \ ''
    \ )
endfunction

function! s:RotateLines()
    let saved_view = winsaveview()
    let first_visible_line = line('w0')
    let last_visible_line = line('w$')
    let lines = getline(first_visible_line, last_visible_line)
    let leading_whitespace = map(
        \ range(len(lines)),
        \ 'matchstr(lines[v:val], ''^\s*'')'
    \ )
    let trailing_whitespace = map(
        \ range(len(lines)),
        \ 'matchstr(lines[v:val], ''\s*$'')'
    \ )
    try
        while 1 " <C-c> to exit
            let lines = map(
                \ range(len(lines)),
                \ '<SID>RotateLine(lines[v:val], leading_whitespace[v:val], trailing_whitespace[v:val])'
            \ )
            call setline(first_visible_line, lines)
            redraw
            sleep 50m
        endwhile
    finally
        if &modified
            silent undo
        endif
        call winrestview(saved_view)
    endtry
endfunction

nnoremap <silent> <Plug>(RotateLines) :<C-u>call <SID>RotateLines()<CR>

nmap \r <Plug>(RotateLines)