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From: lfcs.edinburgh.ac.uk!db@NSS.CS.UCL.AC.UK (Dave Berry)
Newsgroups: comp.compilers
Subject: Lex surrogates
Message-ID: <3286@ima.ima.isc.com>
Date: 5 Feb 89 18:54:03 GMT
Sender: compilers-sender@ima.ima.isc.com
Reply-To: Dave Berry <lfcs.edinburgh.ac.uk!db@NSS.CS.UCL.AC.UK>
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The following references describe scanner generators that are claimed to
produce smaller and faster scanners than Lex.  None of them seem to have
caught on (admittedly the references are fairly recent).  Does anyone have
any experience with these or similar tools?  What problems do they have?
 Do people use Lex just because it's there?

If Lex is as bad as these articles (and my experience) suggest, I'm surprised
that GNU are using it for an optimising compiler.

@Article(gla,
        Author="V. P. Heuring",
        Title="The Automatic Generation of Fast Lexical Analysers",
        Journal="Software Practice and Experience",
        Volume="16",
        Number="9",
        Pages="801-808",
        Month="Sep",
        Year="1986")

@Article(mkscan,
        Author="R. Nigel Horspool and Michael R. Levy",
        Title="{\it Mkscan} -- An Interactive Scanner Generator",
        Journal="Software Practice and Experience",
        Volume="17",
        Number="6",
        Pages="369-379",
        Month="June",
        Year="1987")

@Article(schnorf,
        Author="P. Schnorf",
        Title="Dynamic Instantiation and Configuration of Functionally Extended,
 Efficient Lexical Analysers",
        Journal="{SIGPLAN} Notices",
        Volume="23",
        Number="10",
        Pages="93-102",
        Month="Oct",
        Year="1988")

Dave Berry,	Laboratory for Foundations of Computer Science, Edinburgh.
		db%lfcs.ed.ac.uk@nss.cs.ucl.ac.uk
		<Atlantic Ocean>!mcvax!ukc!lfcs!db
[Lex was a summer student's project that escaped from the lab. I can easily
believe that there are lots of better lexer generators, since although lex's
theory is sound, its implementation leaves a lot to be desired. Gnu isn't
using it, since it's licensed AT&T code, but is probably using a
reimplementation that works. -John]
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