[DFDL-WG] Trimming of a text number that's all zeros when the number pattern has a sign char at the end

[Andrew Edwards]

Hi all,

I've hit an interesting case revolving around trimming and number patterns 
that doesn't seem quite sane to me.

Consider an element with the following properties:
textTrimKind='padChar'
textNumberPadCharacter='0'
textNumberPattern='0000+;0000-'

So we have the sign character at the end of the representation.  Now, 
imagine that the data being parsed is "0000+".  The relevant rules from 
the DFDL specification are:

Section 13.2 on textTrimKind
When 'padChar', the element is trimmed of the dfdl:textStringPadCharacter, 
dfdl:textNumberPadCharacter, dfdl:textBooleanPadCharacter or 
dfdl:textCalendarPadCharacter  depending on the type of the element.
Section 13.6 on textNumberPadCharacter
When parsing, if the pad character is '0' and the SimpleContent region 
consists entirely of '0' characters, then the last remaining '0' is not 
trimmed and a single '0' is the result of the trimming.  This rule also 
applies when the pad character is a DFDL character entity equivalent to 
'0'. This rule does not apply when the pad character is any other 
character nor when a pad byte is specified.
Section 13.6.1
Describes all of the pattern syntax.


In our hypothetical case, the content region is not all zeros, as it ends 
in '+'.  This means that the rule in section 13.6 does not apply and we 
only apply the rule in 13.2.  This results in us trimming away all of the 
zeros and ending up with '+'.  This then doesn't parse as a number.

The problem seems to be that the rule in Section 13.6 doesn't take into 
account that the suffix of the pattern can result in text in the content 
region that isn't part of the digits of the number.  Should the rule under 
section 13.56 be something more like this...

When parsing, if the pad character is '0' and the SimpleContent region 
consists entirely of '0' characters, or the SimleContent region consists 
of a string of '0' characters followed by non-digit characters, then the 
last remaining '0' is not trimmed and a single '0' is the result of the 
trimming.  This rule also applies when the pad character is a DFDL 
character entity equivalent to '0'. This rule does not apply when the pad 
character is any other character nor when a pad byte is specified.

Thoughts?

Andy 
Andy Edwards - IBM Integration Bus - DFDL


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