[DFDL-WG] Unparsing dfdl:lenghtKind='pattern'

[Alan Powell]

The Specification currently says that on unparsing 
dfdl:lengthKind='pattern' behaves like dfdl:lenghtKind='implict' but since 
we limited 'implict' to certain logical/representation  combinations this 
is no longer correct.

Proposals

1. When unparsing complex elements with dfdl:lengthKind='pattern', the 
length is the length of the children (same as 'implicit')
 
When unparsing simple elements with dfdl:lengthKind='pattern'  the length 
is the implicit length for those that have one and  length of the data 
supplied in the infoset converted to the representation with no 
padding/filling for the rest. 

For string/text and hexbinary/binary that is reasonable
For number/text/standard and zoned it is governed by the numberPattern
For number/binary/ binary  use 'implicit' lengths
For number/binary/packed or bcd  use minimum number of bytes
For Calendar/text  it is governed by the calendarpattern
For Calendar/binary/packed or bcd use minimum number of bytes
For Calendar/binary/binarymilliseconds or binaryseconds use implicit 
lengths
For Boolean/text  use the length of the true/false rep.
For Boolean/binary use implicit length (32)


2. A new property dfdl:patternOutputLengthKind

3. We could limit dfdl:lenghtKind 'pattern' to complex elements so that 
there is always a lengthKind for child simple elements but this would 
introduce 'unnecessary' complex items in  the infoset when there is only 
one child.

Alan Powell

 MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
 Notes Id: Alan Powell/UK/IBM     email: alan_powell at uk.ibm.com 
 Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898






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/20100114/75421eab/attachment.html