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| From | glen herrmannsfeldt <gah@ugcs.caltech.edu> |
|---|---|
| Newsgroups | comp.compilers |
| Subject | Re: coupling LALR with a scanner? |
| Date | 2011-10-03 21:08 +0000 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <11-10-008@comp.compilers> (permalink) |
| References | (4 earlier) <11-09-016@comp.compilers> <11-09-017@comp.compilers> <11-09-022@comp.compilers> <11-09-023@comp.compilers> <11-10-003@comp.compilers> |
Chris F Clark <cfc@shell01.theworld.com> wrote:
> I have come to this discussion a little late and may have missed some
> of the conversation, so excuse me if I say some things which are
> obvious and have been discussed before.
(snip)
> However, and here I think we come to the crux of the discussion, can a
> scannerless system disambiguate the potentially ambiguous use of / as
> a division operator and the start of a regular expression? I would
> argue that if the system is LR(k) for some finite k and the use of
> regular expressions is not restricted to some narrow (left, preceding)
> context (e.g. as in Perl where regular expressions are part of only
> specific operations like m/regex/ and ~=/regex/ (forgive me if my Perl
> is a bit rusty)), then the answer is no.
I could be completely missing the point, but it seems to me that you
don't have to restrict such RE to a narrow context as long as the
context isn't one where a division operator is allowed.
Division usually requires a preceding operand. In the contexts I would
expect a regular expression it would be either preceded by an operator
or be the beginning of an expression.
In writing AWK programs, where there are functions that take RE as
operands, I normally put then in quotes (") instead of slashes, as it
seems more obvious in the context. (A variable with the appropriate
value also works.)
-- glen
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coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-07-05 01:02 +0200
Re: coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-07-07 10:28 +0200
coupling LALR with a scanner? "Karsten Nyblad" <uu3kw29sb7@snkmail.com> - 2011-07-07 10:46 +0200
Re: coupling LALR with a scanner? "Karsten Nyblad" <uu3kw29sb7@snkmail.com> - 2011-07-08 14:39 +0200
Re: coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-08-04 11:17 +0200
Re: coupling LALR with a scanner? Paul B Mann <paul@paulbmann.com> - 2011-09-13 13:38 -0700
Re: coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-09-16 10:47 +0200
Re: coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-09-19 13:52 +0200
Re: coupling LALR with a scanner? Paul B Mann <paul@paulbmann.com> - 2011-09-19 12:12 -0700
Re: coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-09-20 09:40 +0200
Re: coupling LALR with a scanner? Chris Dodd <cdodd@acm.org> - 2011-09-23 23:59 +0100
Re: coupling LALR with a scanner? Chris F Clark <cfc@shell01.TheWorld.com> - 2011-09-29 00:00 -0400
Re: coupling LALR with a scanner? "Armel" <armelasselin@hotmail.com> - 2011-10-02 16:41 +0200
Re: coupling LALR with a scanner? Chris F Clark <cfc@shell01.TheWorld.com> - 2011-10-03 11:59 -0400
Re: coupling LALR with a scanner? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2011-10-03 21:08 +0000
Re: coupling LALR with a scanner? Paul B Mann <paul@paulbmann.com> - 2011-09-17 10:38 -0700
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