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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: GOTO considered necessary (reworked)
Date: 1997/06/21
Message-ID: <EC3uEA.MAE@world.std.com>#1/1
X-Deja-AN: 251520237
References: <5nn2fm$11dk$1@prime.imagin.net> <dewar.866548262@merv>
 <EBxrpn.67C@world.std.com> <dewar.866851293@merv>
Organization: The World Public Access UNIX, Brookline, MA
Newsgroups: comp.lang.ada
Date: 1997-06-21T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <dewar.866851293@merv>, Robert Dewar <dewar@merv.cs.nyu.edu> wrote:
>Bob Duff said
>
><<In my experience, a hand-coded lexical analyzer is always better done
>with loops and ifs and case statements, rather than as above.  That is,
>forget that it's a FSM, and just write it in the natural way.  ("An
>identifier is a letter, followed by a sequence of zero or more letters
>and digits" translates quite nicely into loops, not gotos.)  I know you
>agree, since I've seen the GNAT lexer.>>
>
>You may have seen it, but you have not read it all, it has a number of
>gotos of the FSM type in it. Of course it is not full of this, because
>FSM's don't have much to do with lexical analyzers except in unusual cases.

I've read it all.  It has very few gotos (and those, I didn't object
to).  Mostly, it's made of loop/if/case.  It certainly doesn't fit into
the pattern envisioned in this thread about FSM's, where every state
starts with a label, and every state "goto"s the next state.

- Bob