Path: utzoo!attcan!uunet!cs.utexas.edu!hellgate.utah.edu!mailrus!accuvax.nwu.edu!nucsrl!tsaim
From: tsaim@eecs.nwu.edu (Ming-Hsiun Tsai)
Newsgroups: comp.unix.wizards
Subject: Re: yacc reduce/reduce conflict question
Message-ID: <13030009@eecs.nwu.edu>
Date: 6 Sep 89 20:17:08 GMT
References: <718@larry.sal.wisc.edu>
Organization: Northwestern U, Evanston IL, USA
Lines: 64


Dear Jeff:


     The error message on our system is not the same as on your system.
 So, I mis-understand that MNEMONIC_ is a (non-)terminal sysbol. I do the
 two tests below.

     The first one is the one like yours (I hope I do not make any mistake
 this time). Also I append the error message I get from my system.

     The second one is a correct one (YACC does not say anything wrong).

     Comparing the two. I think the problem is the "=" symbol in the rules.
 I don't know if "=" has special meaning translated by yacc. I have no
 yacc manual on hand. If you have, check it out.

     Conclusion: add "'" on both sides of "=". 

     Try it. Hope it work for you. Good luck.


                                 Ming-Hsiun Tsai (Sep. 6, 1989)


---------------------- Example 1.  An error demo ------------------------------

%token MNEMONIC
%start all
%%
all		: cmd_parameter
		| arg
		;

cmd_parameter	: MNEMONIC = MNEMONIC
		;

arg		: MNEMONIC
		;
%%

-------------------------------------------------------------------------------

1 rules never reduced

conflicts: 1 reduce/reduce

--------------- Example 2.  This one may give you some ideas ------------------

%token MNEMONIC
%start all
%%
all		: cmd_parameter
		| arg
		;

cmd_parameter	: MNEMONIC '=' MNEMONIC
		;

arg		: MNEMONIC
		;
%%

-------------------------------------------------------------------------------