Word Count printed in Vim document

Question

I'd like to add to my .vimrc file a function which updates the text in an open document, specifically where it finds the text "Word Count: " it would use vim to insert an accurate word count in the current document.

This is mostly as a programming exercise and to better learn vim, I know there are external programs like wc available to do this work.

Here's an example of a similar function I'm using to count lines of code:

function! CountNonEmpty()
    let l = 1
    let char_count = 0
    while l <= line("$")
        if len(substitute(getline(l), '\s', '', 'g')) > 3   
            let char_count += 1 
        endif
        let l += 1
    endwhile
    return char_count
endfunction

function! LastModified()
  if &modified
    let save_cursor = getpos(".")
    let n = min([15, line("$")])
    keepjumps exe '1,' . n . 's#^\(.\{,10}LOC:\).*#\1' .
          \ ' ' . CountNonEmpty() . '#e'
    call histdel('search', -1)
    call setpos('.', save_cursor)
  endif
endfun

autocmd BufWritePre * call LastModified()

Can someone help me figure out how to add to the LastModified function so that it inserts a word count where it finds the text Word Count in the header?

Answer 1

After some more digging I found the answer. This is code from Michael Dunn, another StackOverflow user, posted at Fast word count function in Vim

I'll post how I incorporated it here in case anyone else finds this portion of my .vimrc to be useful:

function! CountNonEmpty()
    let l = 1
    let char_count = 0
    while l <= line("$")
        if len(substitute(getline(l), '\s', '', 'g')) > 3   
            let char_count += 1 
        endif
        let l += 1
    endwhile
    return char_count
endfunction

function WordCount()
  let s:old_status = v:statusmsg
  exe "silent normal g\<c-g>"
  let s:word_count = str2nr(split(v:statusmsg)[11])
  let v:statusmsg = s:old_status
  return s:word_count
endfunction  

" If buffer modified, update any 'Last modified: ' in the first 20 lines.
" 'Last modified: ' can have up to 10 characters before (they are retained).
" Restores cursor and window position using save_cursor variable.
function! LastModified()
  if &modified
    let save_cursor = getpos(".")
    let n = min([15, line("$")])
    keepjumps exe '1,' . n . 's#^\(.\{,10}LOC:\).*#\1' .
          \ ' ' . CountNonEmpty() . '#e'
    keepjumps exe '1,' . n . 's#^\(.\{,10}Word Count:\).*#\1' .
          \ ' ' . WordCount() . '#e'
    call histdel('search', -1)
    call setpos('.', save_cursor)
  endif
endfun

autocmd BufWritePre * call LastModified()