[DFDL-WG] examples of decimal validation using pattern facet

[Mike Beckerle]

Forgot to distribute this to the WG.

I now recall one of the discussions of patterns on numbers was this.

XML has this characteristic that everything is both a string, and whatever
type it's logical XML Schema type says it is.

So a pattern that requires leading zeros makes sense on an integer because
in XML, everything is a string; hence, we can talk about a pattern facet
for the string-behavior of what XML-schema tells us is an integer.

Not so in DFDL.

In DFDL, the integer is converted to a pure conceptual number. Facet
constraints can have to do only with the value of this logical type. The
facets aren't about the representation. They are about the value only.

Hence, talking about leading zeros on an integer simply doesn’t make sense.
Leading zero is a representation concept.

Here's the simplest way to think about it. If I had binary integers, would
this same pattern facet requiring leading zeros make sense?  --- no it
would not; and therefore it isn't allowed in DFDL for any integers, binary
nor textual representations. Facets must be about the logical value, not
the representation. Hence, patterns aren't allowed on numbers, because
patterns are fundamentally about strings.


On Sat, May 18, 2013 at 2:42 PM, Mike Beckerle <mbeckerle.dfdl at gmail.com>wrote:

>
> Roger costello of Mitre provides this example of using pattern facet.
>
> Basically, it expresses several different possible formats, all of which
> are some combination of digits and a optional decimal point.  In terms of
> cobol-style patterns it is one of these formats:
>
> 99
> 99.9
> 99.99
> 99.999
> 99.9999
>
> I am not sure a textNumberPattern can handle the optionality of the
> decimal point. I know we can deal with the varying number of fraction
> digits, and the fixed number of integer digits, but conditional decimal
> point I am unsure about.
>
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Costello, Roger L. <costello at mitre.org>
> Date: Fri, May 17, 2013 at 4:00 PM
> Subject: RE: examples of decimal validation using pattern facet
> To: Mike Beckerle <mbeckerle.dfdl at gmail.com>
> Cc: "Cranford, Jonathan W." <jcranford at mitre.org>
>
>
>  Hello Mike,****
>
> ** **
>
> **Ø  **Can you send an example of the lat/lon validation ****
>
> **Ø  **you mentioned on yesterday's Daffodil call?****
>
> ** **
>
> Here ya go:****
>
>
>             <xsd:simpleType name="foo">
>                         <xsd:restriction base="xsd:decimal">****
>
>                                     <xsd:minInclusive value="00"/>
>                                     <xsd:maxInclusive value="59.9999"/>
>                                     <xsd:pattern value=
> "[0-9]{2}|[0-9]{2}\.[0-9]{1}|[0-9]{2}\.[0-9]{2}|[0-9]{2}\.[0-9]{3}|[0-9]{2}\.[0-9]{4}"
> />
>                         </xsd:restriction>
>             </xsd:simpleType>****
>
> ** **
>
> /Roger****
>
> ** **
>
> *From:* Mike Beckerle [mailto:mbeckerle.dfdl at gmail.com]
> *Sent:* Thursday, May 16, 2013 8:15 AM
> *To:* Costello, Roger L.
> *Subject:* examples of decimal validation using pattern facet****
>
> ** **
>
> Roger,
>
> Can you send an example of the lat/lon validation you mentioned on
> yesterday's Daffodil call?
>
> The other members of the workgroup are wondering what can't be done via
> totalDigits/fractionDigits, etc.
>
> The rationale for why pattern facet is not supported on numbers in DFDL is
> that we already have a much more powerful mechanism for parsing and
> unparsing numbers called textNumberPattern. The pattern facet only allows
> pass/fail using a regex, and is considered redundant (and problematic) for
> numbers as a result.
>
> ...mike
>
> --
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
> www.tresys.com****
>
>
>
> --
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
> www.tresys.com
>
>


-- 
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
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