More molecular depiction in Vim

The reception for my previous blog post on ASCII depiction in Vim was somewhat muted even, dare I say, lukewarm. Buoyed by this response, I updated that script to handle quoted SMILES strings (as found in my Python scripts, for example). And here I provide similar depiction support for SDF files ("\a" and "\A" for small and big depictions).

Disclaimer: Due to my use of complex regular expressions, this script is not suitable for use by Andrew Dalke, nor for any SDF file provided by same. If this script is used on a SDF file provided by Andrew Dalke, it may result in the summoning of Cthulhu. You have been warned.

function! SDFToAscii(width)
  let prev = search("$$$$", "nbW") + 1
  let end = search("$$$$", "nW")
  if end == 0
    let end = line('$')
  endif
  silent execute prev.",".end."yank"
  let output = system("obabel -isdf -oascii -d -xa 2.0 -xw ".a:width, @")
  botright new
  setlocal buftype=nofile bufhidden=wipe nobuflisted noswapfile nowrap
  put =output
  setlocal nomodifiable
  1
endfunction
noremap <silent> <leader>a :call SDFToAscii(79)<CR>
noremap <silent> <leader>A :call SDFToAscii(189)<CR>