Re: coupling LALR with a scanner?

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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