home/nvim: Update sus whitespace highlighting

1 files changed, 40 insertions, 6 deletions

diff --git a/home/neovim/init.vim b/home/neovim/init.vim
index b2da2aa..b0eb388 100644
--- a/home/neovim/init.vim
+++ b/home/neovim/init.vim
@@ -190,13 +190,47 @@ au BufReadPost *
 	\ 	exe "normal! g'\"" |
 	\ endif
 
-" TODO: Ignore in term:// buffers.
 augroup Sus
 	au!
+
+	" Add syntax groups if relevant. This conditional is compensating for
+	" the lack of negative matches in :au.
+	"
+	" See: https://vim.fandom.com/wiki/Highlight_unwanted_spaces
+	" See: https://stackoverflow.com/questions/6496778/vim-run-autocmd-on-all-filetypes-except
+	fun! s:AddSyntax()
+		if bufname() !~ 'term://\|man://'
+			" Any trailing whitespace at the end of lines.
+			syn match SusWhitespace /\s\+$/ containedin=ALL
+
+			" Any non-breaking spaces. These are generated by
+			" CMD+SPACE and deeply annoying.
+			syn match SusWhitespace /\%u00A0/ containedin=ALL
+
+			" Any characters beyond the maximum width of the text.
+			if &tw > 0
+				exe 'syn match SusWhitespace /\%' . &tw . 'v.\+/ containedin=ALL'
+			endif
+		endif
+	endfun
+
+	" Remove highligt group.
+	"
+	" Note that we have to do abit more work since the the syntax rules
+	" have changed under Vim's nose. Hopefully the perfomance
+	" characteristics don't come back to haunt us.
+	fun! s:RemoveSyntax()
+		syn clear SusWhitespace
+		syn sync fromstart
+	endfun
+
+	" Add a persistent highligt group, which matches are going to use.
 	au VimEnter,ColorScheme * hi SusWhitespace ctermbg=red guibg=red
-	au BufWinEnter * match SusWhitespace /\s\+$/
-	             \ | 2match SusWhitespace /\%u00A0/
-	au InsertEnter * match SusWhitespace /\s\+\%#\@<!$/
-	au InsertLeave * match SusWhitespace /\s\+$/
-	au BufWinLeave * call clearmatches()
+
+	" Create some persistent syntax highlighting groups.
+	au Syntax * call s:AddSyntax()
+
+	" Temporarily remove the groups when in insert mode.
+	au InsertEnter * call s:RemoveSyntax()
+	au InsertLeave * call s:AddSyntax()
 augroup END