Thread-safe code from bison (yacc) and flex (lex)

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2 total messages Started by Donald A. Thompson Sun, 31 Jan 1999 00:00

#6962

Author: Donald A. Thompson
Date: Sun, 31 Jan 1999 00:00

11 lines
1010 bytes

I am looking for versions of bison (or yacc) and flex (or lex) that produce
thread-safe C code.

Alternatively, I'd like pointers on methods to modify the C code produced by
these programs to make the C code thread-safe.  I think the problem is that
some basic data structures (e.g., yytext) in the C code are global
variables.

Thank you.

-Don Thompson

Re: Thread-safe code from bison (yacc) and flex (lex)

#6963

Author: Anders Wegge Jakobsen
Date: Sun, 31 Jan 1999 00:00

23 lines
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"Donald A. Thompson" <dont@pluto.njcc.com> writes:

> I am looking for versions of bison (or yacc) and flex (or lex) that produce
> thread-safe C code.
> 
> Alternatively, I'd like pointers on methods to modify the C code produced by
> these programs to make the C code thread-safe.  I think the problem is that
> some basic data structures (e.g., yytext) in the C code are global
> variables.

 Parsers generated by bison can be made reentrant with the declaration 
%pure_parser. 

 It's a bit harder to make flex scanners thread-safe, but depending on 
the problem at hand, a semaphore wrapped around the flex code might
do the trick. If that's not enough, yy_swithch_to_buffer() and
yy_restart(), will take you a bit further. If you can determine a
finite need for concurrent scanners, the -Pprefix option can at least
give each scanner it's own namespace.

-- 
/Wegge

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