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Re: [xsl] Seek a simple XPath 2.0 expression to return union xs: simpleType containing xs:string


Subject: Re: [xsl] Seek a simple XPath 2.0 expression to return union xs: simpleType containing xs:string
From: "Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 4 Dec 2015 15:12:30 -0000

Correction:

declare function transitive-members-of-union-type($t) {
     let $m := members-of-union-type($t)
     return $m, $m ! transitive-members-of-union-type(.)
};

MK

> On 4 Dec 2015, at 15:07, Michael Kay mike@xxxxxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> You also need to consider a union type U that has a member type V which is
itself a union type with xs:string as a member - that is, you need to consider
the transitive membership of the union, not just its direct membership.
>
> To do this kind of thing, using XPath directly against the source schema is
simply not a suitable strategy. You should be running queries against the
schema component model.
>
> The following query, which uses Saxon extension functions to access the
schema component model, may be helpful:
>
> declare function all-union-types() {
> 	saxon:schema("type definition")[.("variety") = "union"]
> };
>
> declare function members-of-union-type($t) {
>       $t("member type definitions")
> };
>
> declare function transitive-members-of-union-type($t) {
>      let $m := members-of-union-type($t)
>      return $t, $t ! transitive-members-of-union-type(.)
> };
>
> declare function union-type-has-transitive-member-type($t, $n as xs:QName)
{
>    exists ( transitive-members-of-union-type($t) [ .("name") =
local-name-from-QName($n) and .("target namespace") =
namespace-uri-from-QName($n) ]
> };
>
> all-union-types()[ union-type-has-transitive-member-type(.,
xs:QName('xs:string')) ] ! xs:QName( .("target namespace"), .("name") )
>
> (I've made this output the name of each union type, but it's not clear what
you would want to output when the union type is anonymous).
>
>
> Michael Kay
> Saxonica
>
>
>> On 4 Dec 2015, at 13:15, Costello, Roger L. costello@xxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> Hi Folks,
>>
>> I seek an XPath 2.0 expression that returns all XML Schema simpleTypes
containing a union with memberTypes containing the XML Schema string type.
(Phew! Did you catch all that?)
>>
>> So, the XPath should return the union simpleType in this schema:
>>
>>
-----------------------------------------------------------------------------
-----
>> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
>>
>>   <xs:simpleType name="test">
>>       <xs:union memberTypes="xs:int xs:string" />
>>   </xs:simpleType>
>>
>> </xs:schema>
>>
-----------------------------------------------------------------------------
-----
>>
>> The XPath should not return the union simpleType in this schema:
>>
>>
-----------------------------------------------------------------------------
-----
>> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
>>
>>   <xs:simpleType name="test">
>>       <xs:union memberTypes="xs:int string"/>
>>   </xs:simpleType>
>>
>>  <xs:simpleType name="string">
>>      <xs:restriction base="xs:string" />
>>  </xs:simpleType>
>>
>> </xs:schema>
>>
-----------------------------------------------------------------------------
-----
>>
>> I created a horrendously complex XPath 2.0 expression. I think it works
(it's so complex, I'm not sure). Is there a simpler XPath 2.0 expression to
solve this problem?
>>
>> Here's the ugly XPath 2.0 expression that I created:
>>
>> //xs:simpleType[xs:union[@memberTypes]
>>      [exists(index-of(for $here in ., $i in tokenize(@memberTypes, '\s+')
return
>>       namespace-uri-from-QName(resolve-QName($i, $here)) eq
>>          'http://www.w3.org/2001/XMLSchema' and
>>      local-name-from-QName(resolve-QName($i, $here)) eq 'string',
true()))]]
>>
>> /Roger


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