yacc/lex and precompiler statements

Hello,


I have been working on a lex/yacc programme to parse VOS (a language
somewhat like pascal) in order to make a code beautifier. I hate
indenting by myself - it's a computer's job, I think.


As for the parser, it's working quite nicely. I've used the pascal
versions of yacc en lex, and Delphi 2 as the pascal compiler. Now I
get to the difficult part:


IN vos, you can use $IF -- $ELSE -- $ENDIF statements. This is not
difficult for the VOS compiler itself, since it evaluates the $IF
expression and decides which part to skip. My beautifier, however,
should be able to 'PUSH' the yacc stack and, on occurce of an $ELSE,
POP it back.


I've tried to do this in the lexicografical phase (I.E. lex) but
haven't found out how to do this. Any suggestions about this
'precompiler-problem'?


Thanks in advance,


Waldo van Riemsdijk
[Yuck. There have been some messages about a version of yacc that does
conditional reduction of rules, quite useful in parsing some of the worst
parts of C++, but I think this is tougher. In principle, the yacc state
is just a couple of arrays and some pointers, but I fear that getting the
parse restarted and undoing the reductions since you saved the state will
be quite difficult. -John]


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