Can we tokenise a file with a plugin instead of a syntax definition?

[ngppgn]

Does the API for plugins exposes any functionality to assign scopes to parts of text on demand?

I ask because I have a lexer written in c# for a custom language, and it would be way easier for me to port it to python than to a sublime-syntax definition.

[facelessuser]

You are going to have to port it to sublime-syntax definition. Performance wouldn’t be good if Sublime allowed you to do what you are requesting anyways. You want the underlying C code doing it.