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| Related articles |
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| precedences vs. hierarchy bassobajo@gmail.com (Andreas Schramm) (2016-06-06) |
| Re: precedences vs. hierarchy mailbox@dmitry-kazakov.de (Dmitry A. Kazakov) (2016-06-06) |
| Re: precedences vs. hierarchy gneuner2@comcast.net (George Neuner) (2016-06-06) |
| Re: precedences vs. hierarchy federation2005@netzero.com (2016-06-06) |
| precedences vs. hierarchy slkpg4@gmail.com (SLK Mail) (2016-06-07) |
| Re: precedences vs. hierarchy 545-066-4921@kylheku.com (Kaz Kylheku) (2016-06-07) |
| Re: precedences vs. hierarchy mailbox@dmitry-kazakov.de (Dmitry A. Kazakov) (2016-06-07) |
| Re: precedences vs. hierarchy anton@mips.complang.tuwien.ac.at (2016-06-08) |
| From: | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
| Newsgroups: | comp.compilers |
| Date: | Wed, 08 Jun 2016 09:48:49 GMT |
| Organization: | Institut fuer Computersprachen, Technische Universitaet Wien |
| References: | 16-06-001 16-06-004 16-06-008 |
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| Keywords: | parse |
| Posted-Date: | 10 Jun 2016 22:23:21 EDT |
Kaz Kylheku <545-066-4921@kylheku.com> writes:
>You need the concept of associativity to tell whether
>A + B + C is (A + B) + C or A + (B + C).
But if + is really associative (e.g., not FP addition), these two are
equivalent.
>In table shift-reduce parsers (Yacc, and such), associativity rules
>resolve conflicts.
Of course, you can also write the grammar in an unambiguous way, then
you don't need associativity rules to resolve the ambiguity; a
disadvantage of precedence and associativity declarations is that they
can hide more ambiguities than you intended.
- anton
--
M. Anton Ertl
anton@mips.complang.tuwien.ac.at
http://www.complang.tuwien.ac.at/anton/
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