Using other low-weight markups instead of Markdown (specifically asciidoc)

Is there anyway to use other low-weight markup language instead of Markdown? Specifically I am interested in Asciidoc (Asciidoctor) which is more sophisticated, at the same time extendible, than Markdown (O'Reilly authors write book in that).

Asciidoctor, which renders asciidoc files, is in Ruby but it has ports in Javascript (and Java (JRuby)) for both server side or client side rendering. Being able to use .adoc extension files alongside .html, .md or even triggering compilation of adoc to html in the first visit can be helpful.

Markdown is currently quite tightly integrated into Grav. We have discussed making this more pluggable in Grav 2.0, but it's not something in Grav's near future.