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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 15:07:22 -0000

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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