Carefully read through (bottom up--main, slre_compile, etc) this short implementation and all will be clear: http://slre.sourceforge.net/1.0/slre.c http://slre.

Carefully read through (bottom up--main, slre_compile, etc) this short implementation and all will be clear: http://slre.sourceforge.net/1.0/slre.c http://slre.sourceforge.net/1.0/slre.c Also a great introduction to writing compilers.