Hi Folks,
The text data format that I am writing a DFDL schema for has a field (let's
name it "Foo") with a fixed width. Let's say the width is 100 characters. The
content of the field is uppercase letters. If there is no data available to
populate the field, it must be populated with a single hyphen (surrounded by
spaces to ensure the field has a width of 100). The hyphen may be in any
position within the field. For reasons I will not share, I must specify the
field's content using a regex:
lengthKind=pattern
lengthPattern=[A-Z]{100}
However, that lengthPattern doesn't take into account the hyphen that is needed
when there is no data. So I updated the regex like this:
lengthPattern=[A-Z]{100}|[ ]*-[ ]*
However, the right-hand side of that regex (which deals with the hyphen)
doesn't constrain the length of the field. Recall the hyphen may be positioned
anywhere within the 100 character field. Writing a regex that specifies all
possible positions of the hyphen, while ensuring the field is 100 characters,
is not reasonable.
So it would seem that I need to specify length=100 on the element declaration:
lengthKind=explicit
length=100
But now I have conflicting requirements:
1. The element declaration needs to specify lengthKind=pattern for the regex
2. The element declaration needs to specify lengthKind=explicit for the field
length
That's a problem. That's not legal.
It other words, I need this illegal DFDL:
<xs:element name="Foo"
nillable="true"
dfdl: nilValue="-"
dfdl:lengthKind="explicit"
dfdl:length="100"
dfdl:lengthUnits="characters"
dfdl:lengthKind="pattern"
dfdl:lengthPattern="[A-Z]{100}|[ ]*-[ ]*">
<xs:simpleType>
<xs:annotation>
<xs:appinfo source="http://www.ogf.org/dfdl/";>
<dfdl:assert test="{ (fn:nilled(.)) or (. ne '') }"/>
</xs:appinfo>
</xs:annotation>
<xs:restriction base="xs:string"/>
</xs:simpleType>
</xs:element>
Is there a solution to this problem? If not, is there a workaround?
/Roger
