Configure Vim to insert text for Lines of Code

Question

I'm using Vim for all program editing and I have a standard header I use at the top of all my source code files. I have a .vimrc file set up to update certain fields in this header (like Last Modified) when I save any changes using :w

My question is, how do I put in a function to count lines of code, following the basic rule that only non-blank lines are counted?

I know within an open vim buffer, I can use

:%s/\n//gn 

to count all lines, and

:%s/\n\n//gn 

to count blank lines (basically count how many times two newlines appear in a row, indicating a blank line). But how do I put this in my .vimrc file?

Here's the code fragment from my .vimrc that updates the header fields:

function! LastModified()
  if &modified
    let save_cursor = getpos(".")
    let n = min([20, line("$")])
    keepjumps exe '1,' . n . 's#^\(.\{,10}Last Modified:\).*#\1' .
          \ strftime(' %a %b %d, %Y  %I:%M%p') . '#e'
    keepjumps exe '1,' . n . 's#^\(.\{,10}Filename:\).*#\1' .
          \ ' ' . @% . '#e'
    keepjumps exe '1,' . n . 's#^\(.\{,10}LOC:\).*#\1' .
          \ ' ' . '' . '#e'
    call histdel('search', -1)
    call setpos('.', save_cursor)
  endif
endfun

Also, I would just like to add, I know there are numerous other ways to do this (like using wc --lines from the shell) but I'm interested in learning how to really configure my editor (so call it a learning exercise).

Answer 1

You actually should not want to use :s here:

function! CountNonEmpty()
    return len(filter(getline(1, line('$')), '!empty(v:val)'))
endfunction

---

By the way, I would have used getline+map+setline to implement your header updater:

function! LastModified()
    if &modified
        " If number of buffer lines is < 20, then getline(1, 20)"
        " will return only existing lines without any errors "
        call setline(1, map(getline(1, 20), 'substitute(substitute(substitute(v:val, '.
        \'"^\\v(.{,10}Last Modified:).*", "\\1 ".strftime("%s %b %d, %Y  %I:%M%p"), ""),'.
        \'"^\\v(.{,10}Filename:).*",      "\\1 ".escape(@%, "&\\~"), ""),'.
        \'"^\\v(.{,10}LOC:).*",           "\\1 ", "")'))
    endif
endfunction

Answer 2

This might help:

function! CountNonEmpty()
  redir => g:nonblank
  silent %s/^.\+$/&/n
  redir END
  return substitute(g:nonblank, '\n\s*\(\d\+\)\D.*$', '\1', '')
endfunction

• :redir => Stores the output of the following ex commands into the given variable. See :help :redir