Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ncar!ico!haddock!ima!esegue!compilers-sender
From: mkie@vlsivie.at (Inst.f.Techn.Informatik)
Newsgroups: comp.compilers
Subject: Re: Two pass compiler using YACC?
Keywords: yacc, parse, question
Message-ID: <1763@tuvie>
Date: 23 Aug 90 11:08:58 GMT
References: <1364@svin02.info.win.tue.nl>
Sender: compilers-sender@esegue.segue.boston.ma.us
Reply-To: mkie@vlsivie.at (Inst.f.Techn.Informatik)
Organization: Technical University of Vienna, AUSTRIA
Lines: 41
Approved: compilers@esegue.segue.boston.ma.us

In article <1364@svin02.info.win.tue.nl>, wsineel@info.win.tue.nl (e.vriezekolk) writes:
> The problems come during link-time, for ld, obviously, complains about
> multiple defined symbols (such as yylval and yyparse).
> 
> This must be a traditional problem. How is it solved?
The  symbols which make you clash can be renamed by a simple sed 
script 
sed -e 's/yyparse/something_parse/g' \
    -e 's/yylex/something_lex/g' \
    -e 's/yylval/something_lval/g' \
    -e 's/YYSTYPE/something_TYPE/g' \

 [...] you get the idea. 
You will also have to modify the y.tab.h file and the file with
yylex() 

> [I hope the grammars for the two passes are the same, and just the { }
> actions are different.  I always do the obvious thing, if(pass1)... else ...
> in the action routines.  In about half the cases, the action routines do
> something simple like look up an identifier in the symbol table, so the
> conditional code is buried in the lower level routine.  Having separate yacc
> grammars seems to me to be a poor idea if for no other reason than that it is
> a big problem to keep the two files in sync when you make a grammar change.
> -John]
That's the way I do it also, but sometimes you need two parsers in the 
same executable, so this problem does exist at times

				bye,
					mike

Michael K. Gschwind             mike@vlsivie.at
Technical University, Vienna    mike@vlsivie.uucp
Voice: (++43).1.58801 8144      e182202@awituw01.bitnet
Fax:   (++43).1.569697
[Similar suggestions from zs@munginya.cs.mu.OZ.AU (Zoltan Somogyi),
jouvelot@brokaw.lcs.mit.edu (Pierre Jouvelot), and vramsey@NCoast.ORG
(Cedric Ramsey).]

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