[DFDL-WG] proposed dfdl:hexBinary function for hex constants in schemas

[Mike Beckerle]

Separated out from prior proposal where it was mixed in with another topic.

dfdl:hexBinary($arg as xs:anyAtomicType?) as xs:hexBinary?

This function provides an extension to the behavior of the xs:hexBinary
constructor. The argument can be a string, in which case the behavior is as
the xs:hexBinary constructor. The argument can also be a long,
unsignedLong, or any subtype thereof, and in that case a string containing
hexadecimal digits is produced. The hexadecimal digits produced that are
letters are always uppercase. The number of hex digits in the resulting
string is a function of the input type. If byte or unsigned byte, exactly 2
hex digits are produced, for short and unsignedShort, 4 hex digits, and so
on. The hex digits correspond to a big-endian representation of a
twos-complement binary representation of the argument value. So:

dfdl:short(xs:concat('x', dfdl:hexBinary(xs:short(208)))) eq xs:short(208)

is true, and a corresponding tautology holds for all the other DFDL
functions that construct integers from hexadecimal, if you replace the 208
above with a value in range for the corresponding numeric type.

If the argument is a numeric literal, then the smallest signed integer type
(long, int, short, byte) is selected that can contain the value, and the
number of hexadecimal digits produced corresponds to that type. So:

dfdl:hexBinary(208) eq 'D0'
dfdl:hexBinary(-2084) eq 'F7FF'


-- 
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.ogf.org/pipermail/dfdl-wg/attachments/20130716/2134e84f/attachment.html>