Re: [Ltru] Test suite for language tags?

["Doug Ewell" <dewell at adelphia.net>]

Addison Phillips <addison at yahoo dash inc dot com> wrote:

> Your best bet is probably to generate subtag sequences based on the 
> ABNF. Some particular problem cases to check would be:

Just a few minor nits here.  This is slightly more complex than meets 
the eye, unfortunately.

> - singletons in the first position (except for 'x' and the 
> grandfathered list)

Sadly, the existence of the grandfathered list means that all 
well-formed processors must also do a limited amount of validity 
checking.  I don't question the importance of maintaining support for 
the grandfathered tags, but this is a side effect.

> - misplaced extlang (3ALPHA in the third or later position following 
> any of these: 4ALPHA, 2ALPHA, 3DIGIT, 5*8alphanum, DIGIT 3alpha)[note: 
> stop at singleton]

Repalce "following" by "immediately following."  2ALPHA followed by 
3ALPHA followed by 3ALPHA is fine.

"DIGIT 3alpha" here should be "DIGIT 3alphanum".

> - misplaced script (4ALPHA following any of these: 2ALPHA, 3DIGIT, 
> 5*8alphanum, DIGIT 3alphanum)[note: stop at singleton]

Needs another qualifier.  2ALPHA followed by 4ALPHA is fine: "zh-Hans".

> - missing subtag ("--")
> - a dangling hyphen ("foo-bar-baz-") or initial hyphen 
> ("-foo-bar-baz")

The second is really just a special case of the first: a missing subtag 
at the end or beginning, respectively.  One thing I found useful, when 
building my validator, was to parse out the subtags first and check them 
for validity afterward, so the hyphens never become part of the validity 
checking per se.

> Thus, these are all errors:
>
> "a-foo"
> "abcdefghi-012345678"
> "ab-abc-abc-abc-abc"
> "ab-abcd-abc"
> "ab-ab-abc"

Why pick on Abkhasian so much?  :-)

> "ab-x-abc-x-abc" // anything goes after x

Not quite anything, of course:  1*("-" (1*8alphanum))

--
Doug Ewell
Fullerton, California, USA
http://users.adelphia.net/~dewell/



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