How to handle the different dialects of regular expressions (java vs. xsd)?

Question

When I try to validate an XML file against an XSD in java (see this example) there are some incompatibilities between the regular expressions given in the XSD file and the regular expressions in java.

If there is an regular expression like "[ab-]" in the XSD (meaning any of the characters "a", "b" or "-", java complains about a syntax error in the expression.

This is a known bug since 28-MAR-2005, see Sun bug database.

What can I do to work around this bug? Up to now I try to "correct" the XSD file by replacing the "[ab-]" by "[ab\-]", but sometimes this is not an option.

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If you have problems with this bug, too, please vote for it at the Sun bug database!

Answer 1

Since a bug is already filed, I'd recommend you try a different XML Schema processor. There's not going to be a lot you can do about it.

If you can preprocess the stream the XSD is coming in on, then you could create a parser which understands the basic regular expression structure and can fix anything that looks of the form [.*-] (where the .star is not a literal in this case).

Answer 2

Although it may not be the best solution in the world, you could consider using the Sax parser. I have used it for over 3 years now, however I have not done much regex validation with it, so I cannot speak to it's robustness related to that.

Other than that, I think Kaleb is probably correct on the preprocessing side (which is anything but ideal) - you might be able to use a regex for any of the incoming regex'es to do a replace.... although that has quite the code smell about it.

Edit: An additional thought that just came to me. If the regex does not need to be in the xsd - i.e. it is there simply because that was "easiest" in the past - you could do the regex validation outside of the xsd. But, if other systems use the xsd, that is likely not the correct solution, and you can forget I said anything.