wordcount: Replace formatter interface

Currently the formatter, and not the wordcount plugin, is responsible
for providing the wordcount as well as formatting it. The default
formatter allows visual mode word counting, although this is not
documented.

The new interface - a transform() function, allows the main wordcount
plugin to internalise this logic. Providing the wordcount simplifies
formatter implementations:
 - All formatters can display the visual wordcount.
 - Formatters do not have to worry about compatibility with different
   vim versions.

The old format() function can now be deprecated, although the wordcount
plugin retains compatibility with formatters using it. The default
formatter will also be used as a fallback if no suitable function is
found.

The default formatter is rewritten to use the new interface.

autoload/airline/extensions/wordcount.vim

@@ -1,12 +1,59 @@
 " MIT License. Copyright (c) 2013-2018 Bailey Ling et al.
-" vim: et ts=2 sts=2 sw=2
+" vim: et ts=2 sts=2 sw=2 fdm=marker
 
 scriptencoding utf-8
 
-let s:formatter = get(g:, 'airline#extensions#wordcount#formatter', 'default')
+" get wordcount {{{1
-let g:airline#extensions#wordcount#filetypes = get(g:, 'airline#extensions#wordcount#filetypes',
+if exists('*wordcount')
-      \ '\vhelp|markdown|rst|org|text|asciidoc|tex|mail')
+  function! s:get_wordcount(type)
+    return string(wordcount()[a:type])
+  endfunction
+else
+  function! s:get_wordcount(type)
+    " index to retrieve from whitespace-separated output of g_CTRL-G
+    " 11 - words, 5 - visual words (in visual mode)
+    let idx = (a:type == 'words') ? 11 : 5
 
+    let save_status = v:statusmsg
+    execute "silent normal! g\<cn-g>"
+    let stat = v:statusmsg
+    let v:statusmsg = save_status
+
+    let parts = split(stat)
+    if len(parts) > idx
+      return parts[idx]
+    endif
+  endfunction
+endif
+
+" format {{{1
+let s:formatter = get(g:, 'airline#extensions#wordcount#formatter', 'default')
+
+" wrapper function for compatibility; redefined below for old-style formatters
+function! s:format_wordcount(type)
+  return airline#extensions#wordcount#formatters#{s:formatter}#transform(
+        \ s:get_wordcount(a:type))
+endfunction
+
+" check user-defined formatter exists and has appropriate functions, otherwise
+" fall back to default
+if s:formatter !=# 'default'
+  execute 'runtime! autoload/airline/extensions/wordcount/formatters/'.s:formatter
+  if !exists('*airline#extensions#wordcount#formatters#{s:formatter}#transform')
+    if !exists('*airline#extensions#wordcount#formatters#{s:formatter}#format')
+      let s:formatter = 'default'
+    else
+      " redefine for backwords compatibility
+      function! s:format_wordcount(type)
+        if a:type !=# 'visual_words'
+          return airline#extensions#wordcount#formatters#{s:formatter}#format()
+        endif
+      endfunction
+    endif
+  endif
+endif
+
+" update {{{1
 function! s:wordcount_update()
   if empty(bufname(''))
     return
@@ -14,7 +61,7 @@ function! s:wordcount_update()
   if match(&ft, get(g:, 'airline#extensions#wordcount#filetypes')) > -1
     let l:mode = mode()
     if l:mode ==# 'v' || l:mode ==# 'V' || l:mode ==# 's' || l:mode ==# 'S'
-      let b:airline_wordcount = airline#extensions#wordcount#formatters#{s:formatter}#format()
+      let b:airline_wordcount = s:format_wordcount('visual_words')
       let b:airline_change_tick = b:changedtick
     else
       if get(b:, 'airline_wordcount_cache', '') is# '' ||
@@ -22,7 +69,7 @@ function! s:wordcount_update()
             \ get(b:, 'airline_change_tick', 0) != b:changedtick || 
             \ get(b:, 'airline_winwidth', 0) != winwidth(0)
         " cache data
-        let b:airline_wordcount = airline#extensions#wordcount#formatters#{s:formatter}#format()
+        let b:airline_wordcount = s:format_wordcount('words')
         let b:airline_wordcount_cache = b:airline_wordcount
         let b:airline_change_tick = b:changedtick
         let b:airline_winwidth = winwidth(0)
@@ -31,6 +78,11 @@ function! s:wordcount_update()
   endif
 endfunction
 
+" autocmds & airline functions {{{1
+" default filetypes
+let g:airline#extensions#wordcount#filetypes = get(g:, 'airline#extensions#wordcount#filetypes',
+      \ '\vhelp|markdown|rst|org|text|asciidoc|tex|mail')
+
 function! airline#extensions#wordcount#apply(...)
   if match(&ft, get(g:, 'airline#extensions#wordcount#filetypes')) > -1
     call airline#extensions#prepend_to_section('z', '%{get(b:, "airline_wordcount", "")}')

autoload/airline/extensions/wordcount/formatters/default.vim

@@ -3,59 +3,30 @@
 
 scriptencoding utf-8
 
-function! airline#extensions#wordcount#formatters#default#format()
+let s:fmt = get(g:, 'airline#extensions#wordcount#formatter#default#fmt', '%s words')
-  let fmt = get(g:, 'airline#extensions#wordcount#formatter#default#fmt', '%s words')
+let s:fmt_short = get(g:, 'airline#extensions#wordcount#formatter#default#fmt_short', s:fmt == '%s words' ? '%sW' : s:fmt)
-  let fmt_short = get(g:, 'airline#extensions#wordcount#formatter#default#fmt_short', fmt == '%s words' ? '%sW' : fmt)
+
-  let words = string(s:wordcount())
+function! airline#extensions#wordcount#formatters#default#transform(text)
-  if empty(words)
+  if empty(a:text)
     return
   endif
+
   let result = g:airline_symbols.space . g:airline_right_alt_sep . g:airline_symbols.space
   if winwidth(0) >= 80
     let separator = s:get_decimal_group()
-    if words > 999 && !empty(separator)
+    if a:text > 999 && !empty(separator)
       " Format number according to locale, e.g. German: 1.245 or English: 1,245
-      let words = substitute(words, '\d\@<=\(\(\d\{3\}\)\+\)$', separator.'&', 'g')
+      let text = substitute(a:text, '\d\@<=\(\(\d\{3\}\)\+\)$', separator.'&', 'g')
+    else
+      let text = a:text
     endif
-    let result = printf(fmt, words). result
+    let result = printf(s:fmt, a:text). result
   else
-    let result = printf(fmt_short, words). result
+    let result = printf(s:fmt_short, a:text). result
   endif
   return result
 endfunction
 
-function! s:wordcount()
-  if exists("*wordcount")
-    let l:mode = mode()
-    if l:mode ==# 'v' || l:mode ==# 'V' || l:mode ==# 's' || l:mode ==# 'S'
-      let l:visual_words = wordcount()['visual_words']
-      if l:visual_words != ''
-        return l:visual_words
-      else
-        return 0
-      endif
-    else
-      return wordcount()['words']
-    endif
-  elseif mode() =~? 's'
-    return
-  else
-    let old_status = v:statusmsg
-    let position = getpos(".")
-    exe "silent normal! g\<c-g>"
-    let stat = v:statusmsg
-    call setpos('.', position)
-    let v:statusmsg = old_status
-
-    let parts = split(stat)
-    if len(parts) > 11
-      return str2nr(parts[11])
-    else
-      return
-    endif
-  endif
-endfunction
-
 function! s:get_decimal_group()
   if match(get(v:, 'lang', ''), '\v\cC|en') > -1
     return ','
@@ -64,3 +35,4 @@ function! s:get_decimal_group()
   endif
   return ''
 endfunction
+