RE: [HACKERS] Postgres' lexer
От | Ansley, Michael |
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Тема | RE: [HACKERS] Postgres' lexer |
Дата | |
Msg-id | 1BF7C7482189D211B03F00805F8527F70ED114@S-NATH-EXCH2 обсуждение исходный текст |
Список | pgsql-hackers |
>> Hi! Hi, Leon >> I'm currently fooling around with Postgres's parser, and I must admit >> some things puzzle me completely. Please tell me what these things in >> lexer stand for: >> >> {operator}/-[\.0-9] { >> yylval.str = pstrdup((char*)yytext); >> return Op; >> } >> Is it an operator followed by mandatory '-' and (dot or digit) ? I think this is used to recognize an operator followed by a minus or any single character (the period is escaped, the character can be used to denote the base of the number) or a single digit. But check this, I'm not totally sure. >> And what this stands for: >> >> {identifier}/{space}*-{number} An identifier followed by any number of spaces, and then a minus, or a number. Again, double check this with a reference of some sorts. >> >> What's the meaning of all these? >> You really should get a reference that deals with regular expressions. My understanding is (anybody feel free to comment here) that flex uses normal regular expressions to generate scanners. Cheers... MikeA
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