Re: Reachability of DFA part

Andy <>
Sat, 21 Dec 2019 01:15:58 -0800 (PST)

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Related articles
Reachability of DFA part (Andy) (2019-12-20)
Re: Reachability of DFA part (Kaz Kylheku) (2019-12-20)
Re: Reachability of DFA part (Andy) (2019-12-21)
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Re: Reachability of DFA part (Kaz Kylheku) (2019-12-24)
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From: Andy <>
Newsgroups: comp.compilers
Date: Sat, 21 Dec 2019 01:15:58 -0800 (PST)
Organization: Compilers Central
References: 19-12-008 19-12-009
Injection-Info:; posting-host=""; logging-data="80896"; mail-complaints-to=""
Keywords: lex
Posted-Date: 21 Dec 2019 13:10:00 EST
In-Reply-To: 19-12-009

W dniu piątek, 20 grudnia 2019 17:41:04 UTC+1 użytkownik Kaz Kylheku
> In the NFA automaton, every time the prefix of the input given so far
> ends in ba, the machine will be in an acceptance state corresponding
> to that trailing ba.

Machine finally accept all strings begin from "ab" but "ba" will unused.
This is similar to definition of comment: in Pascal. comment begin at { and
end of }, careless definition is {*} which mark as comment to rest of file.

Good definition would be {[^}]*}
Complexity of problem increases when comment ends with string len >1, for
example C: */ or Pascal *)
if we renaming : /->a *->b other->c
then bad definition will ab(a|b|b)*ba and good definition is complicated:
ab(b|(a|c)*b*)*a (if I not make mistake)

Commments should maybe be defined in other way, especially comments can be
nested in Object Pascal. Comment nesting can using stack or simply counter. I
see, in Pascal is using counter. Difference: Pascal has two types of multiline
comments { } and (* *)

If we use stack, closing comment type must be equal last open comment type,
for counter - only count comments of type first opening, example
{ { (* } *) }

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