In my think, TM grammar is change of CFG which can even delete symbols not only add
Automaton Grammar Notion
What is packrat parsing?
At a high level: Packrat parsers make use of parsing expression grammars (PEGs) rather than traditional context-free grammars (CFGs). Through their use of PEGs rather than CFGs, it's typically easier to set up and maintain a packrat parser than a traditional LR parser.