RE: [HACKERS] Postgres' lexer
От | Ansley, Michael |
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Тема | RE: [HACKERS] Postgres' lexer |
Дата | |
Msg-id | 1BF7C7482189D211B03F00805F8527F70ED11C@S-NATH-EXCH2 обсуждение исходный текст |
Ответы |
Re: [HACKERS] Postgres' lexer
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Список | pgsql-hackers |
Leon, if you manage to find a replacement for this, please let me know. I'll probably only pick it up after the weekend. I think that we need to find another way to tokenise the minus. First of all, though, how is the parser supposed to tell whether this: a -2 means this: (a - 2) or this: a (-2) i.e.: does the unary - operator take precedence over the binary - operator or not? Is there even a difference. If the parser runs into this: 'a -2', perhaps we could replace it with 'a + (-2)' instead. How does a C compiler tokenize this? Or some other standard SQL parser? MikeA >> -----Original Message----- >> From: Leon [mailto:leon@udmnet.ru] >> Sent: Friday, August 20, 1999 3:34 PM >> To: hackers >> Subject: Re: [HACKERS] Postgres' lexer >> >> >> Ansley, Michael wrote: >> > >> > Leon, I see that you have been running into the vltc >> problem ;-) I just run >> > a flex -p, and went to line 314. >> >> I got it. It is done to prevent minus from sticking to number in >> expressions like 'a -2'. Dirty, but it works. >> >> -- >> Leon. >> --------- >> "This may seem a bit weird, but that's okay, because it is weird." - >> Perl manpage. >> >> >> ************ >>
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