refashion MySQL parse engine problem(bison, flex)

[feeling wu]

Hi,
I want to extend the SQL statement of MySQL on windows32. For example,I want to make the following statement valid.

<create_policy_stmt>::=
CREATE SECURITY POLICY policy_name [<with_option>]
<with_option>::=
WITH OPTION {{NO}|{LABEL UPDATE}| {CHECH CONTROL}}[,…]

I think there are two parts in MySQL, lexer and semantic parse.And I want to konw that which file should I modify?

And I modify sql_yacc.cpp like this:
copy a linux version sql_yacc.yy to windows, use bison 2.1 compile it. This will produce two files sql_yacc.cpp, sql_yacc.h,
and I use them to instead the same file in windows version of MySQL source file. did I do it right?

Then I want to kown where can I add the new key words, since there is not any *.l file that can be compiled by flex.
Could give me the detail step that how can I extend SQL in MySQL?
Thank you!
Wish for your reply!