How to syntax highlight line with three parts?

Question

I am trying to highlight lines like these:

-> Some text without a domain
-> Some other text with a domain (example.com)

I would like:

a) the leading "->" not to be highlighted; b) the text to be highlighted with, say, Underlined; c) and the domain if given to be highlighted with, say, Comment.

This achieves (a) and (b) but not (c):

syntax region MyLink start=/^-> /hs=e end=/\v(\s\(\a+[.]\a{2,3}\))?$/he=s-1
highlight link MyLink Underlined
syntax match Domain /\v\(\a+[.]\a{2,3}\)/
highlight link Domain Comment

I have tried add contained and contains etc but haven't quite found the right answer.

Any help much appreciated!

Answer 1

You were on the right track! You just need to either:

Add containedin=MyLink to your definition of Domain:

syntax match Domain /\v\(\a+[.]\a{2,3}\)/ containedin=MyLink

or:

Add contains=Domain to your definition of MyLink:

syntax region MyLink start=/^-> /hs=e end=/\v(\s\(\a+[.]\a{2,3}\))?$/he=s-1 contains=Domain