" Sort function from Gerald Lai at http://www.vim.org/tips/tip.php?tip_id=923 
" paste in vimrc file - tested with GVim 6.3

"** use visual block <Ctrl-V> to select lines to sort and hit <F3> **
vmap <F3> :call Sort(Prompt("0","1"),Prompt("1","f"),"Strcmp")<CR>

"sort lines function
function Sort(wnum, order, cmp) range
  normal `<
  execute "let startcol = col(\".\")"
  normal `>
  execute "let endcol = col(\".\")"
  if startcol <= endcol
    let firstcol = startcol
    let lastcol = endcol
  else
    let firstcol = endcol
    let lastcol = startcol
  endif

  call SortR(a:firstline, a:lastline, firstcol, lastcol, a:wnum, a:order, a:cmp)
  normal gv
endfunction

"sort lines recursively
function SortR(start, end, first, last, wnum, order, cmp)
  if a:start >= a:end
    return
  endif

  let partition = a:start - 1
  let middle = partition
  let partstr2 = Words2(getline((a:start + a:end) / 2), a:first, a:last, a:wnum)
  let i = a:start

  while i <= a:end
    let str = getline(i)
    let partstr = Words2(str, a:first, a:last, a:wnum)
    if a:order == "r"
      execute "let result = ".a:cmp."(partstr2, partstr)"
    else
      execute "let result = ".a:cmp."(partstr, partstr2)"
    endif

    if result <= 0
      "swap i before partition
      let partition = partition + 1

      if result == 0
        let middle = partition
      endif

      if i != partition
        let str2 = getline(partition)
        call setline(i, str2)
        call setline(partition, str)
      endif
    endif

    let i = i + 1
  endwhile

  "make sure middle element at end of partition
  if middle != partition
    let str = getline(middle)
    let str2 = getline(partition)
    call setline(middle, str2)
    call setline(partition, str)
  endif

  call SortR(a:start, partition - 1, a:first, a:last, a:wnum, a:order, a:cmp)
  call SortR(partition + 1, a:end, a:first, a:last, a:wnum, a:order, a:cmp)
endfunction

"determine compare strings
function Words2(line, first, last, wnum)
  if a:wnum == "v"
    return strpart(a:line, a:first - 1, a:last - a:first + 1)
  elseif a:wnum > 1
    return strpart(a:line, matchend(a:line, "\\s*\\(\\S*\\s*\\)\\{".(a:wnum - 1)."}"))
  elseif a:wnum == 1
    return strpart(a:line, matchend(a:line, "\\s*"))
  elseif a:wnum < 0
    return matchstr(a:line, "\\(\\S*\\s*\\)\\{".(-a:wnum)."}$")
  else
    return a:line
  endif
endfunction

"compare two strings
function Strcmp(str1, str2)
  if a:str1 < a:str2
    return -1
  elseif a:str1 > a:str2
    return 1
  else
    return 0
  endif
endfunction

"prompt user for settings
function Prompt(str, ...)
  let default = a:0 ? a:1 : ""
  if a:str == "0"
    let str = "Sort by which word [(0)whole line (<0)count from right (v)isual]? "
  elseif a:str == "1"
    let str = "Order [(f)orward (r)everse]? "
  endif

  execute "let ret = input(\"".str."\", \"".default."\")"

  return ret
endfunction