Add autocompletion for available boolean options

README.mkd

@@ -20,7 +20,8 @@ nnore <Leader>i :Onoff list<cr>
 
 For those who want to use `:Onoff` command explicitly, `:onoff` abbreviation is
 available. Abbreviation works on when 'onoff' is the first word on the command
-line.
+line. Note that `:Onoff` command has autocompletion for all available boolean
+options supported by your Vim distribution.
 
 Installation
 ------------

autoload/onoff.vim

@@ -22,3 +22,37 @@ fun! onoff#toggle(option)
 endf
 
 " }}}
+" Read file content line by line {{{
+
+fun! s:readfile(fname)
+  let fname = fnameescape(a:fname)
+  if filereadable(fname)
+    return readfile(fname)
+  endif
+  return []
+endf
+
+" }}}
+" Autocompletion {{{
+
+fun! s:complist()
+  let complist = []
+  let pattern = '\*''no\(\w\+\)'''
+  for line in s:readfile($VIMRUNTIME . '/doc/options.txt')
+    let value = matchstr(line, pattern)
+    if !empty(value)
+      call add(complist, substitute(value, pattern, '\1', ''))
+    endif
+  endfor
+  return sort(complist)
+endf
+
+fun! onoff#compfunc(...)
+  " Cache completion list on first call for later reuse
+  if !exists('s:cache')
+    let s:cache = join(s:complist(), "\n")
+  endif
+  return s:cache
+endf
+
+" }}}

doc/onoff.txt

@@ -42,6 +42,9 @@ works only when 'onoff' is the first word on the command line.
 :Onoff [option]         Switch value of boolean option and show new value at
                         bottom of the window.
 
+                        Note: command has autocompletion for all available
+                        boolean options in your Vim distribution.
+
 ==============================================================================
 3. About                                                         *onoff-about*
 

plugin/onoff.vim

@@ -12,7 +12,9 @@ let g:loaded_onoff = 1
 " }}}
 " Public API {{{
 
-command! -nargs=1 Onoff
+command! -nargs=1
+      \ -complete=custom,onoff#compfunc
+      \ Onoff
       \ call onoff#toggle(<f-args>)
 
 cabbr onoff <c-r>=(getcmdtype() == ':' && getcmdpos() == 1 ? 'Onoff' : 'onoff')<cr>