[DFDL-WG] Trimming of a text number that's all zeros when the number pattern has a sign char at the end
Steve Hanson
smh at uk.ibm.com
Mon Nov 3 10:39:23 EST 2014
Andy
I agree that the existing words do not cover all the scenarios. Your
proposed words are on the right track but only cover left trimming a right
justified text number. We need something that is independent of
justification and can handle patterns where there is quoted text as well
as signs.
One can envisage some bizarre scenarios. Eg, Text number pattern is
"#0'000'" - an attempt to divide by 1000 using the pattern. DFDL parser
would trim everything except 1 zero which would not match the pattern
which expects at least 3 zeros. Trimming happens before pattern is looked
at so I don't think we could cater for this (if we even wanted to).
Perhaps we should say:
When parsing, if the pad character is '0' and dfdl:textTrimKind is
'padChar' then if the SimpleContent region is trimmed so that the removal
of a '0' character leaves the next character other than a digit, the last
'0' character is re-instated and not trimmed. 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.
That means that "000,000,123" would end up as "0,000,123" instead of
",000,123" today and "0000.025" would end up as "0.025" instead of ".025"
today but I think that is good.
Regards
Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
From: Andrew Edwards/UK/IBM at IBMGB
To: DFDL-WG <dfdl-wg at ogf.org>
Date: 30/10/2014 16:43
Subject: [DFDL-WG] Trimming of a text number that's all zeros when
the number pattern has a sign char at the end
Sent by: dfdl-wg-bounces at ogf.org
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
Email:
andy.edwards at uk.ibm.com
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