Message-Id: <199704010232.VAA29138@delorie.com>
Date: Mon, 31 Mar 1997 17:40:34 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: djgpp-announce AT delorie DOT com
Subject: ANNOUNCE: GNU Flex 2.5.4 uploaded to SimTel.NET
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


This is to announce that the DJGPP port of the latest GNU Flex version
2.5.4 has been uploaded to SimTel.NET mirrors:

   ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/flx254b.zip
   ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/flx254s.zip

What is Flex?  Flex is the GNU version of a fast lexical analyzer
generator.  A lexical analyzer, or a scanner, is a program which
recognizes lexical patterns in text.  The simplest case of a scanner
is a function that tries to match words against a set of known
keywords using the standard C function `strcmp'.  A more flexible
scanner would use regular expressions to look for matches.  But as the
number of different regular expressions grows, these home-grown
scanners quickly become grossly inefficient, because they need to test
for a match against every regexp in turn.  Flex-generated scanners are
table-driven C functions (state machines) which, when run, test for a
match against all regular expressions in parallel, so they are very
fast.

Generating such fast scanners is very tedious and error-prone
procedure if you do it manually, and the resulting C code is utterly
unreadable by humans.  Flex is a tool that accepts a human-readable
description of the regular expressions and C code rules that should be
run for every such expression, and produces the code of a C function
called `yylex'.  When compiled and linked with the -lfl library (which
is also part of the package), this function will look for occurrences
of the specified regexps, and if found, execute the corresponding C
rules.

Please read the DOS-specific README file in the distribution, for
instructions and last-minute notes specific to MSDOS.  The NEWS file
is also included in the binary zip file, for those who want to know
what are the improvements since the previous version.