Bug in query parser?

[gmauro]

Hi, I think I have discovered a bug in the Suneido query parsing algorithm.

The following code in the Workspace:

a = 0

a = a - 1 + 1

of course it will generate 0 as output.

Now, if you go in a QueryView and do something like:

create testTable(field1) key(field1)



insert {field1:0} into testTable



testTable extend field2 = field1 - 1 + 1

The output of the query will not be 0, but -2 !!!
Very strange behaviour…

[amckinlay]

Good one! I can recreate it.

It appears to be treating it as: field1 – (1 + 1)

It works if you do: testTable extend field2 = (field1 – 1) + 1

jSuneido does not appear to have this bug – maybe because it shares the expression parser between the language and the database.

I will get this fixed. Thanks for reporting it!

[amckinlay]

I found the problem and fixed it.

The parsing code was incorrect and implemented right associativity instead of left. I am surprised we did not find this before now. I guess we do not usually use complicated expressions in queries.

The code for parsing expressions in the language was correct, but I did not keep the two version consistent 🙁

jSuneido does not have this problem because it shares the expression parsing code with both the language and queries.

I will post a new snapshot but if you need the fix right away, let me know.

http://suneido.svn.sourceforge.net/viewvc/suneido/trunk/qparser.cpp?r1=1111&r2=1110&pathrev=1111

[gmauro]

Hi Andrew, if you could post a snapshot with the bug fixed it would be very nice. Thanks!

[amckinlay]

done!

[gmauro]

Thank you for the snapshot but there are some problems… I will explain them in the Announcements section of the forum, in the thread of the snapshot: link.

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