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| From | gah4 <gah4@u.washington.edu> |
| Newsgroups | comp.compilers |
| Subject | Re: How detect grammar not derive nonterminals ? |
| Date | Thu, 14 Sep 2023 20:04:30 -0700 |
| Organization | Compilers Central |
| Sender | johnl%iecc.com |
| Approved | comp.compilers@iecc.com |
| Message-ID | <23-09-007@comp.compilers> (permalink) |
| References | <23-09-001@comp.compilers> <23-09-002@comp.compilers> <23-09-006@comp.compilers> |
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| Keywords | parse, design, comment |
| Posted-Date | 15 Sep 2023 19:14:46 EDT |
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| In-Reply-To | <23-09-006@comp.compilers> |
| Xref | csiph.com comp.compilers:3525 |
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(our moderator wrote) > [At the very least, you'd need some rules that don't have nonterminals > on the right side to make it possible to break loops. -John] So do it by back propagation. Mark all rules that have a terminal on the right side. Mark all rules that have a rule that has a terminal on the right side. Repeat until there aren't any more to mark. Any unmarked rules don't ever reach a terminal. [It's not quite that, it's rules that have no nonterminals, that is, either just terminals or empty. This will recognize a possibly empty sequence of x's: A: /* nothing */ A: x A -John]
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How detect grammar not derive nonterminals ? Andy <borucki.andrzej@gmail.com> - 2023-09-11 08:58 -0700
Re: How detect grammar not derive nonterminals ? gah4 <gah4@u.washington.edu> - 2023-09-12 22:08 -0700
Re: How detect grammar not derive nonterminals ? Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-14 03:41 +0000
Re: How detect grammar not derive nonterminals ? gah4 <gah4@u.washington.edu> - 2023-09-14 20:04 -0700
Re: How detect grammar not derive nonterminals ? Andy <borucki.andrzej@gmail.com> - 2023-09-13 13:17 -0700
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