flex/bison upgrade

I have a small project written in C++ using flex and bison. The project was originally written using lex/yacc, and does not make use of some of the flex/bison additions.? I wish to upgrade the code. The tasks are to alter the code so that: 1) flex/bison uses the %bison-bridge option 2) flex/bison uses the %bison-location option 3) flex/bison uses the %reentrant option 4) bison garbage collects after a syntax error 5) reading from a string uses the built-in flex method 6) the final interface behaves as a token input to bison The bison parser has one static variable that will need to be accomodated in order to make the flex/bison stack re-entrant.? Also, a trivial bison parser will need to be contructed to demonstrate the last task. The code will come as a tarball with a makefile and a unit test. flex version 2.5.35 and bison version 2.4.1 Partial payment will be made for completed tasks; not finishing all tasks will NOT result in no payment.