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[Bug 2247] R-255: Value of pattern facet

From: <bugzilla@wiggum.w3.org>
Date: Wed, 14 Sep 2005 19:45:17 +0000
To: www-xml-schema-comments@w3.org
Message-Id: <E1EFdC1-0002FW-SG@wiggum.w3.org>


           Summary: R-255: Value of pattern facet
           Product: XML Schema
           Version: 1.0
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: XSD Part 2: Datatypes
        AssignedTo: cmsmcq@w3.org
        ReportedBy: sandygao@ca.ibm.com
         QAContact: www-xml-schema-comments@w3.org

How are multiple pattern facet children represented in the schema component 
infoset? The pattern facet schema component has a value which is a regular 
expression. So presumably, that value is the disjunction of all patterns among 
the children. Is that so? How is the disjunction written? "p1|p2|p3", for 

What about pattern facets at different levels in the derivation? The rec says 
they are effectively ANDed together, but how is that represented in the schema 
infoset, as there is no conjunction operator in the regex language? Is the 
schema processor to figure out the conjunction? Or do the base and derived 
patterns stay separate, with the processor required to walk the base chain for 
the ANDing? Or are there multiple pattern facets in the component model? I'm 
guessing the patterns at different derivation steps stay separate, but it's 
only a guess. 

Relevant part of rec (part 2): 

Schema Representation Constraint: Multiple patterns 
If multiple <pattern> element information items appear as [children] of a 
<simpleType> the [value]s should be combined as if they appeared in a single 
regular expression as separate branches. Note: It is a consequence of the 
schema representation constraint Multiple patterns ( and of the rules 
for restriction that pattern facets specified on the same step in a type 
derivation are ORed together, while pattern facets specified on different steps 
of a type derivation are ANDed together. 

Related member-only thread: Facet equality: questions/issues

Received on Wednesday, 14 September 2005 19:45:28 UTC

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