bison tutorial: contribution to mfcalc.y

[graf hans-rudolf]

Hello!

I have something useful to add to the bison tutorial example
"mfcalc". It is a scanner description for flex, which shows how
to replace the manually written scanner from the tutorial with 
a generated one. 
For me, just learning how to use "yacc and lex", it would have 
been useful to have this simple example to get the "full picture".
I wrote it for personal study and think it could be useful for 
others too, so I would like to contribute it.

Regards, Hans

mfcalc.lex
Description: mfcalc.lex