[NTG-context] Grammar to parse TeX input?

Dear list, I use a buffer to make some text processing. That text contains TeX macros etc… and I’d like to know if there is some feature in lua to parse the text to extract bits which macros, normal text etc… ? Thanks Best regards Joseph Example of pseudo MWE follows. \startluacode function zzz_function(text) - How to process ‘text’ to get bits which are macros, groups etc… ? Eventually expanded ? end \stopluacode \definebuffer[ZZZBuffer] \def\StartZZZ{\grabbufferdata[ZZZBuffer][StartZZZ][StopZZZ]} \def\StopZZZ{\ctxlua{zzz_function(buffers.getcontent('ZZZBuffer'))}} \StartZZZ \input knuth \StopZZZ