[hibernate-dev] Locale to/from String

[Steve Ebersole]

I have had a comment in LocaleType for quite some time to convert
fromString handling to use the Locale.Builder introduced in Java 7.  As
part of the 6.0 work I took a quick look at this.

I think we handle this incorrectly for certain cases currently.

Currently we implement toString(Locale) via Locale#toString, where the
authors specifically say "If both the language and country fields are
missing, this function will return the empty string, even if the variant,
script, or extensions field is present (you can't have a locale with just a
variant, the variant must accompany a well-formed language or country
code)."

However in fromString we actually allow for such cases.  Consider this test:

assertEquals(
        "___ch123",
        LocaleTypeDescriptor.INSTANCE.toString(
                LocaleTypeDescriptor.INSTANCE.fromString( "__ch123" )
        )
);

This actually ends up failing.  The assertion fails.
LocaleTypeDescriptor.INSTANCE.fromString(
"__ch123" ) does in fact parse us a Locale with no language, no
country/region and a variant of "ch123".  In fact if I check the Locale
fields individually they are all set that way.

However, as per that javadoc note, the call to LocaleTypeDescriptor#toString
(Locale#toString) returns "".

So the question becomes what we want to support here.  If the described
Java behavior is to not allow a Locale with just a variant (no language nor
country/region) I think we may want to enforce that here too.

Thoughts?