[DFDL-WG] Action 086: Nils and Defaults for complex elements

[Alan Powell]

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
-------------------------------------------------------------------------------------------------------------------------------------------
IBM
MP211, Hursley Park
Hursley, SO21 2JN
United Kingdom
Phone: +44-1962-815073
e-mail: alan_powell at uk.ibm.com






Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU





-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.ogf.org/pipermail/dfdl-wg/attachments/20100430/6e972194/attachment.html