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From: ma168abq@sdcc7.UUCP (Daniel T. Lau)
Newsgroups: net.micro.amiga
Subject: Re: Recursive descent compilers (from Re: Amiga OS)
Message-ID: <256@sdcc7.UUCP>
Date: Fri, 7-Feb-86 15:22:38 EST
Article-I.D.: sdcc7.256
Posted: Fri Feb  7 15:22:38 1986
Date-Received: Tue, 11-Feb-86 04:27:34 EST
Organization: U.C. San Diego, Academic Computer Center
Lines: 25

> 
> Recursive descent parsers have many advantages over a bottom up parser.  The
> best advantage is good error recovery and error messages.  Recursive descent
> doesn't have to be any slower than bottom up, although it isn't necessarily
> faster, either.  
HAH!!!
Why does recursive descent have better error recovery than LL(1)
parsers?? It doesn't.  What matters is how the programmer implements
error handling/recovery.  It is easier to implement error recovery
using Recursive Descent parsing,  but if you understand LL(1)
parsing, error recovery/handling isn't so bad.  Just pop off the 
bad symbols until you get to a known point, and try to continue
parsing from there.  If you can't continue.. Oh well.

>About the only real advantage to a YACC style parser is that
> the language accepted is described in one place, in an abstract fashion that
> can be easy to read and maintain (although this doesn't necessarily apply to
> the UNIX C compiler).  Of course, this is not to say that recursive descent is
> hard to maintain.
THE REAL ADVANTAGE OF AN LL(1) PARSER IS THAT IT ACCEPTS AS INPUT A
WIDER RANGE OF LANGUAGES THAN A RECURSIVE DESCENT PARSER WOULD. 
> 	    The views expressed above are my opinions only.
:-))

Larry D. Laus