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From: silvert@cs.dal.ca (Bill Silvert)
Newsgroups: comp.lang.fortran
Subject: Fxref & Flink -- deficiencies?
Message-ID: <1989Jul3.125106.27708@cs.dal.ca>
Date: 3 Jul 89 12:51:06 GMT
Organization: Habitat Ecology Div., Bedford Inst. of Oceanography
Lines: 32

Mike Fischbein has pointed out to me that the fxref and flink utilities
which I have written and distributed do not handle suitably obfuscated,
but perfectly legal, Fortran code.  For example, they cannot find
the correct variable names in the following lines of code:

	DO 100 I = 1.5
	DO100I = 1,5

and Mike wonders whether lex-based analyzers can handle Fortran syntax.

As the above example shows, lexical analysis of Fortran requires
complete analysis of each line.  Ignoring blanks is easy (just modify
input.h as distributed with flink and fxref to skip blanks), but a
complete analytical tool would have to include the complete Fortran
parser.  Therefore I always use white space to separate tokens in my
code, and the tools I develop use this to simplify the task.  If you
don't insert white space, my tools won't help you.

Granted, it is cute to include code like MY MAN = NO GOOD in one's code,
but flink and fxref don't know from cute.  I am sure that lex could
handle this sort of thing if one worked at it (BASIC has the same
problem, and I have seen a BASIC written with lex), but where I work we
write very simple, straightforward, and (I hope) clean code, and these
tools do the job for us.

By the way, if anyone has a Fortran beautifier available, we would like
to get one.
-- 
Bill Silvert, Habitat Ecology Division.
Bedford Institute of Oceanography, Dartmouth, NS, Canada B2Y 4A2
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