From: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: A really subtle lexer bug |
Date: | 2018-08-23 15:29:23 |
Message-ID: | 871sap1658.fsf@news-spur.riddles.org.uk |
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Lists: | pgsql-hackers |
>>>>> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> Patch attached.
>> This fixes two bugs: first the mis-lexing of two-char ops as mentioned
>> originally; second, the O(N^3) lexing time of strings of - or +
>> characters is reduced to O(N^2) (in practice it's better than O(N^2)
>> once N gets large because the bison stack gets blown out, ending the
>> loop early).
Tom> Looks reasonable offhand (didn't test). A couple of thoughts:
Tom> * Some regression tests exercising these code paths might be a
Tom> good thing.
Agreed. Any preferences where they should go?
Tom> * There should likely be a comment near where EQUALS_GREATER and
Tom> friends are defined, pointing out that if we add any more
Tom> multi-character operators with special precedences, this code has
Tom> to be taught about them.
Agreed; will do this.
--
Andrew (irc:RhodiumToad)
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