Re: followpos for '?' and '+' operators

Clint Olsen <clint@0lsen.net>
31 Jan 2006 12:48:03 -0500

          From comp.compilers

Related articles
followpos for '?' and '+' operators meeta.gupta@yahoo.com (Meeta Gupta) (2006-01-31)
Re: followpos for '?' and '+' operators clint@0lsen.net (Clint Olsen) (2006-01-31)
Re: followpos for '?' and '+' operators jburgy@gmail.com (jburgy) (2006-01-31)
Re: followpos for '?' and '+' operators rpboland@gmail.com (Ralph Boland) (2006-02-02)
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From: Clint Olsen <clint@0lsen.net>
Newsgroups: comp.compilers
Date: 31 Jan 2006 12:48:03 -0500
Organization: Compilers Central
References: 06-01-130
Keywords: lex, DFA

On 2006-01-31, Meeta Gupta <meeta.gupta@yahoo.com> wrote:
> But How Can I Calculate The Followpos For '?' And '+' Operators? How
> Should I Handle These Operators When I Build The Syntax Tree For A
> Regular Expression.


Since you already know the rules for the '*', '.' and '|' operators, you
can intuitively figure out how to do it for '+' and '?'. Hint: You can
rewrite the syntax tree for '?' and '+' using the operators you already
know. So, '+' is the same as '{re}*' and so on...


-Clint



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