** Resending the tables as a Word doc as they were getting corrupted.

Alan

I think empty must really mean empty - no sequence initiator or separator(s) or terminator. If you have any of those then there is content, the complex element is there, and you apply defaulting to the children.  

I struggled with the tables.  I've changed them both to make it clear that they apply to the complex element as a unit and to avoid overlap with the simple elements tables.


Regards

Steve Hanson
Strategy, Common Transformation & DFDL
Co-Chair, OGF DFDL WG
IBM SWG, Hursley, UK,
smh@uk.ibm.com,
tel +44-(0)1962-815848


From: Alan Powell/UK/IBM@IBMGB
To: dfdl-wg@ogf.org
Date: 30/04/2010 16:26
Subject: [DFDL-WG] Action 086: Nils and Defaults for complex elements
Sent by: dfdl-wg-bounces@ogf.org





Part of Action 086 is to apply the clarified Nils and Defaulting rules to complex elements and develop some examples.

The tables for parsing and unparsing are simpler because there is no need to consider nillable.

I have assumed
-  emptyValueDelimiterPolicy does apply to complex elements.
- on parsing a complex element is empty if its children's content is empty. That is the child delimiters may be present.
- on unparsing defaulting occurs if a complex item is missing or present present but has no children.

Defaulting for complex elements on parsing
initiator region
content region
Logical Value
matching
Not empty
parsed children
matching
empty
 A default is specified
emptyValueDelimiterPolicy
must be
initiator or both
default value
of children
empty
Not empty
Initiator must not be specified
parsed children
empty
empty
A default is specified
emptyValueDelimiterPolicy
must be
none
or
Initiator must not be specified
default value
of children




Defaulting for complex elements on unparsing
Logical Value
initiator region contains
content region contains
Missing or present with no children
default of all children is empty string
emptyValueDelimiterPolicy
none
empty
empty
emptyValueDelimiterPolicy
initiator or both
initiator string
default of any child is not empty string
initiator string
 representation of the child default value.
a least on child exists
initiator string
representation of children

Examples

Defaulting Complex types

ONE:one,
TWO:
  TWOONE:twoone;
  TWOTWO:twotwo;
  TWOTHREE:twothree,
THREE:three
<end>


In the following TWO is 'empty' (when relevant dfdl properties are set)

ONE:one,THREE:three<end>
|separatorPolicy='suppressed', emptyValueDelimiterPolicy='none'

ONE:one,,THREE:three<end>
separatorPolicy='required', emptyValueDelimiterPolicy='none'

ONE:one<end>
separatorPolicy='suppressed' or 'suppressedAtEnd', emptyValueDelimiterPolicy='none'

<end>
separatorPolicy='suppressed' or 'suppressedAtEnd', emptyValueDelimiterPolicy='none'

ONE:one,TWO:,THREE:three<end>
separatorPolicy= don't care , emptyValueDelimiterPolicy='initiator'

ONE:one,TWO:<end>
separatorPolicy= 'suppressed' or 'suppressedAtEnd', emptyValueDelimiterPolicy='initiator'

ONE:one,TWO:,<end>
separatorPosition='postfix'
separatorPolicy= 'suppressed' or 'suppressedAtEnd', emptyValueDelimiterPolicy='initiator'

*** Should 'postfix' separator be there when 'supressedAtEnd'  ***

ONE:one,TWO:TWOONE:,THREE:three<end>
separatorPolicy= 'suppressed' or 'suppressedAtEnd', (TWO)emptyValueDelimiterPolicy='initiator'
(TWOONE)emptyValueDelimiterPolicy='initiator'


ONE:one,TWOONE:,THREE:three<end>
separatorPolicy= 'suppressed' or 'suppressedAtEnd', (TWO)emptyValueDelimiterPolicy='none'
(TWOONE)emptyValueDelimiterPolicy='initiator'

*** We should discuss this example. ***
 
Regards
 
Alan Powell
 
Development - MQSeries, Message Broker, ESB
IBM Software Group, Application and Integration Middleware Software
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Phone: +44-1962-815073
e-mail: alan_powell@uk.ibm.com


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