Highlight Multiple Lines of Comments

Question

I'm on Ubuntu 18.04, vim-gtk3 8.0.

I'm trying to get gvim to highlight multiple lines of comment that starts with a particular word. For example, consider the word 'NOTE':

// NOTE(Ryan): This would be highlighted,
// So would this line
// And this line

// This line would not be highlighted

My current attempt looks like this:

syntax region NoteRegion start=#//\s*NOTE#hs=s+2 end=#\n[^/][^/]#he=s-1
highlight NoteRegion guifg=Red

What I intend this to do is start a region with a // followed by any number of whitespace and then the word NOTE. The highlighting would start after the //, hence the hs=s+2 (I know this won't work for consecutive lines). The region would end with a new line followed by any two characters that are not /. To avoid highlighting these last two characters I have the he=s-1.

Unfortunately this does not work.

Any suggestions would be greatly appreciated.

EDIT: To avoid my highlights being overwritten, my new attempt is:

augroup CommentMarkers
  autocmd!
  autocmd Syntax * syntax region NoteRegion start=#//\s*NOTE# end=#\n(\n|.|[^/][^/])#he=s-1
augroup END
highlight NoteRegion guifg=Red

Answer 1

Your code isn't far off at all. The problem is that your end marker is a newline followed by two characters which aren't /, and this doesn't appear in your file anywhere!

One fix would be to end instead on any line that is empty or that starts (after whitespace) with any non-/ character:

syntax region NoteRegion start=#//\s*NOTE#hs=s+2 end=#^\s*\($\|[^/\t ]\)#he=s-1

If you don't want any of your comment markers highlighted, one simple fix is to use two groups only one of which is highlighted:

syntax region NoteRegion start=#//\s*NOTE# end=#^\s*\($\|[^/\t ]\)#
syntax match NoteHighlight #//\zs.*# containedin=NoteRegion contained
highlight NoteHighlight guifg=Red

Answer 2

I think this will do what you want, except that the highlighting includes the initial //. I don't know any way to do that; adding /s+2 to the end of the search pattern positions the cursor on the 3rd character:

/\/\/\s\+NOTE.*\n\(\/\/\s\+.*\n\)\+

But running a preliminary :global command will produce the highlighting you want, thus:

:%g@//\s\+NOTE@/\s\+NOTE.*\n\(\/\/\s\+.*\n\)\+

I've used @ signs on the :global command to reduce the number of confusing \s a bit. Explanation: the :global (:g) command does a preliminary search for all lines beginning // NOTE. The secondary search (/\s+NOTE etc)is carried out only on the results produced by :g, and does not highlight the // because they are not included in its search pattern. See :h :g for full details.