Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!uwvax!oddjob!kaon!nucsrl!naim
From: naim@eecs.nwu.edu (Naim Abdullah)
Newsgroups: comp.lang.c
Subject: Are yacc parsers portable ?
Message-ID: <3950010@eecs.nwu.edu>
Date: 30 Jul 88 01:41:48 GMT
Organization: Northwestern U, Evanston IL, USA
Lines: 28

[I am a sporadic reader of this newsgroup, so please forgive me if this
 question has been beaten to death here].
 
Is the C parser produced by yacc, portable ? I was looking at it and it had
stuff like:

yyparse() {

	short yys[YYMAXDEPTH];

	register short yystate, *yyps, yyn;
        ...
	yyps= &yys[-1];
	...
}

It seems to me that negative indices on arrays are probably not portable.
Is it really necessary for yacc to do these tricks, or can it produce
portable code that is just as efficient ? Is bison any better in this respect ?

Thank you.

		      Naim Abdullah
		      Dept. of EECS,
		      Northwestern University

		      Internet: naim@eecs.nwu.edu
		      Uucp: {oddjob, chinet, att}!nucsrl!naim