[antlr-interest] Please give me your valuable advice about antlr .

[Frank Yue]

Dear  Prof. Terence Parr:
       Hello! I am sorry to disturb you. Could you please answer some
questions I met?
If I want to know more about the code-generating mechanism of antlr,
and modify them freely based on the generated codes according to my
requests, how should I do? what knowledge of compilers principle
should I know? If possible, could you please give me some related
documents?
       Thank you for reading this letter, waiting for your kind reply!