Hi again, fredt answered to my post on hsgldb-users so i'll follow it up here:
> In short, the parser is hand written. You can extend it if you wish to > accept any extensions to the syntax. So that means, there is no parser generator of any sort which transforms some grammar file into corresponding java code? > Beyond that, you need to implement the > extra processing to return the results of fuzzy and ordinal searches. Ok I'm aware of this. >HSQLDB is relatively easy to adapt but this task is not among the simplest >ones. I see. I think I'll look into the source the next days and see how far I get there. Can you give maybe a hint about which classes would be affected/need to be modified? Then I'll come back with my questions. :) cu, Johannes ------ > > > Hello everyone, > > as I already posted on hsqldb-users (sorry wasn't aware of hsqldb-developers): > > > My question was: Which parser hsqldb is using? > Is it javacc etc., or a parser you have developed yourself? > > Whould it be possible to change the way hsqldb parses the sql, as for > implementing an enhanced version of sql, with additional > keywords/expressions etc? > > The background: > I'm studying applied computer science in germany, and for my diploma > thesis, I'm enhancing an application developed at our university > (university of augsburg, http://www.uni-augsburg.de/). > This application is called Preference SQL, it enhances standard SQL > with the notion of preferences. > One can for example state a query like > SELECT * FROM usedcars > WHERE make = 'Ford' > PREFERRING price AROUND 20000 > AND HIGHEST(power) > PRIOR TO color = 'red' > for which I guess the meaning is quite obvious. > > The difference to standard SQL is that the conditions in the PREFFERING > clause don't have to be matched exactely, but rather are treated as soft > selections. So if there's no exact match, the best matching entries are > returned. (I can give you more background about this if someone should > be interested :) ). > > Until now, the program is implemented in the way that a JDBC driver > takes the PreferenceSQL statement, connects the the underlying > (standard) sql database (oracle, mysql etc), fetches all the nessesary > tables with hard selections (WHERE..), and executes the preference part > of the query on this data. > To parse the query, we use a JavaCC generated parser. > > My task would be to implement the exection of preference queries > directly into a java database, and I was told to use your hsqldb. > So I would adapt the classes that do the parsing on the incoming query, > so that they can handle the extended syntax. > > My questions would be: > What do you think of that task and it's complexity? > How is your parser organized/what parser do you use? > Whould it be possible to convert our javacc parser to your parser format? > How much of the code would I have to change to implement execution of > preference queries? > > many thanks for your answers, > > regards, Johannes > > ______________________________________________________________ > Verschicken Sie romantische, coole und witzige Bilder per SMS! > Jetzt bei WEB.DE FreeMail: http://f.web.de/?mc=021193 > > > > ------------------------------------------------------- > SF.Net email is Sponsored by the Better Software Conference & EXPO > September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices > Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA > Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf > _______________________________________________ > hsqldb-developers mailing list > hsqldb-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/hsqldb-developers ______________________________________________________________ Verschicken Sie romantische, coole und witzige Bilder per SMS! Jetzt bei WEB.DE FreeMail: http://f.web.de/?mc=021193 ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ hsqldb-developers mailing list hsqldb-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/hsqldb-developers
