Vim syntax match for variable definitions

[tdewolff]

This adds a match for variable definitions so that they can be highlighted using a color scheme. Variable definitions are the foo and bar in:

foo := ...
foo, bar := ...

[arp242]

Two comments:

1. It only seems to work for the last variable? Using this:

   :syn match goVarDefs /\w\+\(,\s*\w+\)*\s*\ze:=/
   :hi def link goVarDefs Statement
   

   Gives me (the brownish colour being Statement):

   

   Is this intentional? It seems strange to me (I would expect both a and err to be highlighted).

2. The syntax groups isn't highlighted by default, but will still be applied, which will be a performance hit. You should probably put this behind a variable (like the existing g:go_highlight_* ones).

[tdewolff]

Hmm that is strange, it works for multiple variable for me (that's the (,\s* ... ) part). I'll do some testing

EDIT: hm, I've double checked and tested, but it works fine for both a and err for me, can you confirm that you copied the goVarDefs correctly?

[arp242]

Just tested again; it really doesn't work for me in Vim 8.0.987 with the current vim-go master, even in my "minimal" setup without vimrc and just the vim-go plugin.

It looks like the problem is you forgot to add a \ to the + inside the capture group; if I add that it works:

syn match goVarDefs /\w\+\(,\s*\w\+\)*\s*\ze:=/

I don't know why it works for you...

Also, to avoid highlighting spaces between the last variable and := (only shows if you set the highlight to something with a different background colour):

syn match goVarDefs /\w\+\(,\s*\w\+\)*\ze\(\s*:=\)/

And with \v added to cure the Leaning Toothpick Syndrome and make it a wee bit more readable:

syn match goVarDefs /\v\w+(,\s*\w+)*\ze(\s*:\=)/

[tdewolff]

Ah I see you are well versed in Vim regexes. I've changed it.

[fatih]

@Carpetsmoker I've added you to the repo. From now on please feel free to merge & review syntax based PR's as I think you're the best fit. Just don't forgot to update the Changelog.

[arp242]

Thanks @fatih 👍