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From: johnl@ima.UUCP (Compilers mailing list)
Newsgroups: mod.compilers
Subject: Generator of Lexical Analyzers, mini-review
Message-ID: <130@ima.UUCP>
Date: Mon, 16-Jun-86 21:47:46 EDT
Article-I.D.: ima.130
Posted: Mon Jun 16 21:47:46 1986
Date-Received: Wed, 18-Jun-86 23:40:37 EDT
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Really-from: decvax!utzoo!henry

I got a copy of the Colorado group's tech report on GLA (Generator for
Lexical Analyzers) and wasn't terribly impressed.  It may be fast, but
it's a lot of machinery for rather modest results.  It is very much
oriented towards fairly conventional programming languages, and is not
a general-purpose substitute for LEX (I don't think they ever claimed
it was, but the point should be made more explicitly).  It's not even
very versatile at handling programming languages; for example, it can't
handle C's hexadecimal numbers or string continuations.

To my mind, the most useful part of the package would be several libraries
provided with it, encapsulating things like string storage and target-
machine integer arithmetic.  Given the limited domain of application of
GLA, I suspect that a better approach would be to invest a bit more effort
on the libraries and supply a "boilerplate" C scanner invoking them.  The
problem of scanning conventional programming languages just isn't complex
enough to justify a program-generator system.  (Caveat:  I haven't seen the
software, just the tech report, but I'd be very surprised if there was much
hidden complexity.  I have written lexical analyzers, including two for C.)

I must admit, though, it's cheap enough:  $25 plus two signed copies of
the license agreement.  In fact, I'd suggest raising the price, because
$25 will barely cover materials costs and can't possibly cover the time
and effort needed to do software distribution.  (I've done such work.)

				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry
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