Re: Calling two times yyparse reloading yyin

[Tim Van Holder]

Ismael Moreno wrote:
> void cAssigNode::translate(cVM& vm)  throw(std::exception)
> {
>     char* Text;
>     Text = strdup(RValue.c_str());
> 
>     FILE* yyin = fmemopen(Text, strlen(Text), "r");
>     if(yyin == NULL)
>         throw(cError("Can't open yyin stream"));
> 
>     yyparse();

yyparse() (well, yylex() really) can't (and won't) use your
function-local yyin.
Note that adjusting the code to use the global yyin won't necessarily
work; flex will only cleanly switch to the new yyin if it got an EOF
state on the original one.  Using yyrestart(), you to tell flex/bison
that a new "file" should be processed, even if the current/previous
one wasn't fully processed (so that flex can clear its internal cache).
So put a "yyrestart(yyin);" before each yyparse() and things should
work.
Depending on your lexer you may want to add a function of your own
(say, yy_new_file()) to your .l file, that not only calls yyrestart(),
but also sets the lexer state back to INITIAL (so that a parse error
inside a state in the first yyparse() does not break the second
yyparse()).
You typically want to test yyparse()'s return value too, so that
you can detect parse errors.

> [snip]
>     delete Text;

Memory allocated by malloc() (even indirectly via strdup()) should be
freed using free(), not delete.

I'm not sure the strdup() is even needed - I would expect that
  fmemopen(RValue.c_str(), RValue.size(), "r");
works just as well.