Quickly expand current working directory into cmdline

directory-expand.vim

" Use // in certain commands like :edit, :split, :read, etc. to insert the current buffer's directory
" :e// -> :e foo/bar/
"
" Compatible commands:
" :edit/:split/:vsplit
" :find/:sfind
" :buffer/:sbuffer
" :read
" :diffpslit/:diffpatch
" :vimgrep/:grep

cnoremap <expr> / <SID>current_dir("/", "\<bs>")

function! s:current_dir(char, start)
  let cmdline = getcmdline()
  let type = getcmdtype()
  if type != ':'
    return "\<c-]>" . a:char
  endif
  if cmdline =~# '\v<(e%[dit]!?|sp%[lit]!?|vs%[plit]!?|fin%[d]!?|sf%[ind]|b%[uffer]!?|sb%[uffer]!?|r%[ead]|diffs%[plit]|diffp%[atch]|vimg%[rep](\s*/.{-}/|\s\S.{-})\s|grep.{-}\s)\s*/$'
    return a:start . (cmdline =~ '\s/$' ? '' : "\<space>") . expand('%:h:gs?\\?\/?') . '/'
  endif
  return "\<c-]>" . a:char
endfunction