🚀 go-pugleaf

(Apologies for the widespread distribution of this message - I could not
find a suitable forum for flex/lex discussions, and dejanews pointed to
multiple newsgroups for intelligent discussions).

I am currently working on a parser that uses both flex and bison to parse
text which is contained within a string. Everything works great, but I
actually call yyparse from main(), and would like to loop through multiple
strings, tokenizing and parsing each string separately.

At present, I have a main routine that does some stuff with text retrieved
from the file system, then places it in a buffer that is globally accessible
- my rewritten YY_INPUT accesses this buffer and works from it instead of
*yyin (as described in Levine et al's ORA book). 

This works great, but if I call yyparse() from within a loop, and for each
iteration of the loop I repoint my globalbuffer pointer to a new string so
that it is visible from YY_INPUT, YY_INPUT is still pointing at the original
chunk of memory, and doesn't want to think about the new strings.

I have looked into the capabilities of yywrap, but all examples that I have
found seem to be suitable for input _files_ that throw <<EOF>> tokens at the
end. I, of course, don't have this - I get a \0 at the end of my string that
indicates an EOS (end of string). In fact, when I get to the end of a
string, yywrap doesn't get called.

Is there no way for me to easily have:

main() {
  ...
  for(i=0; i<5; i++) { // for 5 strings...
    // create new string and do stuff with it
    // point to new string
    yyparse(); // Run yyparse() nice and clean as if nothing has been run
    report_results();    
  }
}

I've been bashing my head against the wall with this one for quite some time
- any answers would be a greatly appreciated. Really, if I could just figure
out how to "clean up" between calls to yyparse() so that I was always
starting at square one, that would be ideal. I suspect that's what yywrap()
simulates with multiple files, but I can't benefit from those examples.

   Thanks in advance,

Steve Franklin
franklin@ug.c.sdal.ca