While developing the Tao Language for the APE computers (see the TAO Language Book), Pier Stanislao Paolucci,with Simone Cabasino and Gianmarco Todesco, invented a new type of grammar, that we called "Evolving Grammar". An Evolving Grammar is able to capture a changing context. Intuititevely, we could say that it realizes this capacity by evolving a succession of internal Context Free Grammars. The language contains statements capable to change its own grammar!
See our paper "Dynamic Parsers and Evolving Grammars" appeared on ACM SIGPLAN Notices, Volume 27 Issue 11, Nov. 1992.
The parser able to accept languages is Zz.
Attached the preprint of the "Dynamic Parser and Evolving Grammars" paper.