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From: drw@cullvax.UUCP (Dale Worley)
Newsgroups: net.lang
Subject: Re: Faster parser driver for yacc?
Message-ID: <362@cullvax.UUCP>
Date: Tue, 7-Oct-86 11:56:12 EDT
Article-I.D.: cullvax.362
Posted: Tue Oct  7 11:56:12 1986
Date-Received: Wed, 8-Oct-86 06:35:20 EDT
References: <2250001@hpfclq.HP.COM>
Organization: Cullinet Software, Inc., Westwood, MA
Lines: 21

> Does anyone have any guidelines on how the structure of the input grammar
> will affect the efficiency of the resulting parser (eg, number of
> levels of non-terminal, etc.)?

Avoid productions like

	a : b ;

if possible.  It helps to use precedence rules with an ambiguous
grammar.  Thus you can write things like

	expr : expr '+' expr
	     | expr '*' expr
	     | '-' expr
	     | '(' expr ')'
	     ;

and use precedence rules to sort things out.  This avoids alot of
nonterminals whose sole purpose is keeping the precedences straight.

Dale