The only machine generated files are pbasic.tab.c, pbasic.tab.h, and lex.yy.c. All the other files were written by me. I also don't tend to use goto's in my code.
But basically all the generated parsers are are state machines. And some of the code that actually gets put in the generated files was written by me. Bison and Flex have the ability (and it's used most of the time) to put code insert code inline. If you look at the various pbasic.y and pbasic.l files you can see where the code that's dropped in inline is.
Matt