LOGO to C++ conversion

I have been asked from my job to make a meta-compiler.My job is take user programs written in LOGO(Its for a school)and convert them with preprocessor and C++11 meta programming techniques to C++ code. What i am trying to do right now is suppose we have this expression in our file

MAKE var = NUMBER: 21

that defines a variable called var and assigns the number 21 in it.

I have to convert it to something C++ like auto var = 21; while compiling with g++.

I have defined MAKE as auto but i cant figure out how i will place ; at the end of the expression at compile time and change NUMBER: with something else that C++ will accept as i cant define : in preprocessor. I am not sure that auto var = 21; is the final form i have to find the solution whatever works accepted.