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RE: XML Schema Part 2: Datatypes Appendix E Regular Expression

From: Biron,Paul V <Paul.V.Biron@kp.org>
Date: Wed, 12 Dec 2001 09:21:56 -0800
Message-Id: <8904C60CACA7D51191BC00805FEAAF43BF69@crdc-exch-7.crdc.kp.org>
To: "'Sverre Hvammen Johansen'" <sj@birdstep.com>, "'www-xml-schema-comments@w3.org'" <www-xml-schema-comments@w3.org>
> -----Original Message-----
> From:	Sverre Hvammen Johansen [SMTP:sj@birdstep.com]
> Sent:	Tuesday, December 11, 2001 7:39 AM
> To:	www-xml-schema-comments@w3.org
> Subject:	Bug: XML Schema Part 2: Datatypes Appendix E Regular
> Expression
> 
> I am working on an implementation of regular expression based on the
> specification found in XML Schema Part 2, appendix E.
> 
> I have found one construct which is ambiguous:
> 
>   [.]
> 
> There are two possible leftmost derivations for this construct:
> 
>   regExp => branch => piece => atom => charClass => charClassExpr =>
>   '[' charGroup ']' => '[' posCharGroup ']' => '[' charRange ']' =>
>   '[' XmlCharInDash ']' => '[.]'
> 
> and:
> 
>   regExp => branch => piece => atom => charClass => charClassExpr =>
>   '[' charGroup ']' => '[' posCharGroup ']' => '[' charClassEsc ']' =>
>   '[' MultiCharEsc ']' => '[.]'
>          
> The first alternative gives the single character '.' while the second
> gives the multi character escape 'any character'.  I expect that the
> first alternative is the intended solution for the specification.
> 
> I suggest to change the specification to the following:
> 
>   [11]   charClass   ::=  charClassEsc | charClassExpr | '.'
>   [37]   MultiCharEsc::=  '\' [sSiIcCdDwW]
> 
Thanx for your comment.  This ambiguity has already been identified and is
noted in the Schema Errata [1] as E2-10.

pvb

References
[1] http://www.w3.org/2001/05/xmlschema-errata#Errata2
Received on Wednesday, 12 December 2001 12:36:55 GMT

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