Note: The reason why fn:position()
takes no argument is because it gives position in the current sequence.
Which is also why we have a separate DFDL specific function dfdl:occursIndex()
which is intended for giving position in enclosing array. I think we need
an argument that targets the specific enclosing array.
Regards
Steve Hanson
Architect, IBM
DFDL
Co-Chair, OGF
DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848
From:
Tim Kimber/UK/IBM@IBMGB
To:
dfdl-wg@ogf.org,
Date:
28/07/2014 23:51
Subject:
Re: [DFDL-WG]
clarification on dfdl:occursIndex() function
Sent by:
dfdl-wg-bounces@ogf.org
I agree that it is inconvenient for
the 'nearest array parent' to be inaccessible. However, experience with
discriminators makes me fearful of any rule that includes the phrase 'nearest
enclosing' :-)
I think at least one other DFDL function allows the target of the function
to be specified as an argument, but insists that the argument must be in
the dynamic scope of the element ( i.e. its parent/grandparent etc ). I
would be much happier with that solution for occursCountIndex().
I can think of a use case where it may be useful to get a consistent behaviour
for occursCountIndex(). If a DFDL schema is generated from some other data
format description then the model generation code may want to refer to
the nth occurrence of something else in the model, where n is the occurs
index of the current element - regardless of whether this particular element
is an array.
regards,
Tim Kimber,
From: Mike
Beckerle <mbeckerle.dfdl@gmail.com>
To: "dfdl-wg@ogf.org"
<dfdl-wg@ogf.org>
Date: 28/07/2014
23:27
Subject: [DFDL-WG]
clarification on dfdl:occursIndex() function
Sent by: dfdl-wg-bounces@ogf.org
This function says it can be called on non-array elements. However, it
does not say what the result is.
If called when "." is not itself an array element there are only
two possible behaviors consistent with the fact that it is explicitly allowed
on non-array elements.
The result has to be either
(a) 1
(b) the occursIndex of the nearest enclosing array parent, or 1 if there
is no enclosing array parent.
I claim (a) is fairly pointless. You will just end up having to create
newVariableInstances to carry the array current index downward into expressions.
I cannot think of a use case where one would want to call occursIndex()
polymorphically, i.e., where you want a number in the case of an array,
but 1 otherwise.
So (b) is the preferable behavior.
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are
subject to the OGF
Intellectual Property Policy
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