1 files changed, 104 insertions, 0 deletions
diff --git a/plugin/toggle_option_flag.vim b/plugin/toggle_option_flag.vim
new file mode 100644
index 0000000..bc7ccd7
--- /dev/null
+++ b/plugin/toggle_option_flag.vim
@@ -0,0 +1,104 @@
+"
+" toggle_option_flag.vim: Provide commands to toggle flags in grouped options
+" like 'formatoptions', 'shortmess', 'complete', 'switchbuf', etc.
+"
+" Author: Tom Ryder <tom@sanctum.geek.nz>
+" License: Same as Vim itself
+"
+if exists('g:loaded_toggle_option_flag') || &compatible
+  finish
+endif
+if !has('user_commands')
+  finish
+endif
+let g:loaded_toggle_option_flag = 1
+
+" Show an error-highlighted message and beep, but without a real :echoerr
+function! s:Error(message)
+  execute 'normal! \<Esc>'
+  echohl ErrorMsg
+  echomsg a:message
+  echohl None
+endfunction
+
+" Test whether an option currently has a flag as part of its value
+function! s:Has(option, flag)
+
+  " Horrible :execute to get the option's current setting into a variable
+  " (I couldn't get {curly braces} indirection to work)
+  let l:current = ''
+  execute 'let l:current = &' . a:option
+
+  " If the flag we're toggling is longer than one character, this must by
+  " necessity be a delimited option. I think all of those in VimL are
+  " comma-separated. Extend the flag and value so that they'll still match at
+  " the start and end. Otherwise, use them as-is.
+  if strlen(a:flag) > 1
+    let l:search_flag = ',' . a:flag . ','
+    let l:search_value = ',' . l:current . ','
+  else
+    let l:search_flag = a:flag
+    let l:search_value = l:current
+  endif
+
+  " Return whether
+  return stridx(l:search_value, l:search_flag) > -1
+
+endfunction
+
+" Internal function to do the toggling
+function! s:Toggle(option, flag, local)
+
+  " Check for spurious option strings, we don't want to :execute anything funny
+  if a:option =~# '\m\L'
+    call s:Error('Illegal option name')
+    return 0
+  endif
+
+  " Check the option actually exists
+  if !exists('&' . a:option)
+    call s:Error('No such option: ' . a:option)
+    return 0
+  endif
+
+  " Choose which set command to use
+  let l:set = a:local
+        \ ? 'setlocal'
+        \ : 'set'
+
+  " Find whether the flag is set before the change
+  let l:before = s:Has(a:option, a:flag)
+
+  " Assign -= or += as the operation to run based on whether the flag already
+  " appears in the option value or not
+  let l:operation = l:before
+        \ ? '-='
+        \ : '+='
+
+  " Try to set the option; suppress errors, we'll check our work
+  silent! execute l:set
+        \ . ' '
+        \ . a:option . l:operation . escape(a:flag, '\ ')
+
+  " Find whether the flag is set after the change
+  let l:after = s:Has(a:option, a:flag)
+
+  " If we made a difference, report the new value; if we didn't, admit it
+  if l:before != l:after
+    execute l:set . ' ' . a:option . '?'
+  else
+    call s:Error('Unable to toggle '.a:option.' flag '.a:flag)
+  endif
+
+  " Return value is whether we made a change
+  return l:before != l:after
+
+endfunction
+
+" User commands wrapping around calls to the above function
+command -nargs=+ -complete=option
+      \ ToggleOptionFlag
+      \ call <SID>Toggle(<f-args>, 0)
+command -nargs=+ -complete=option
+      \ ToggleOptionFlagLocal
+      \ call <SID>Toggle(<f-args>, 1)