Syntax and parsing architecture

[vikigenius]

I have been reading through the architecture docs to gain and understanding of the design choices made here. It's very helpful.

But the one thing I couldn't get a clear answer on is, how is lexing handled? Is there a separate lexing phase where the file is converted into a list of tokens? Is it lazy? Or is it more of an on demand lexing where the parser determines how and what to lex?