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FunctX XQuery Functions

functx:precedes-not-ancestor

Whether an XML node precedes another without being its ancestor

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Description

The functx:precedes-not-ancestor function returns a boolean value indicating whether $a precedes $b without being its ancestor. If either argument is the empty sequence the function returns false.

Arguments and Return Type

NameTypeDescription
$a node()? the first node
$b node()? the second node
return value xs:boolean

XQuery Function Declaration

See XSLT definition.
declare namespace functx = "http://www.functx.com";
declare function functx:precedes-not-ancestor
  ( $a as node()? ,
    $b as node()? )  as xs:boolean {

   $a << $b and empty($a intersect $b/ancestor::node())
 } ;

Examples

let $in-xml :=
<authors>
   <author>
      <fName>Kate</fName>
      <lName>Jones</lName>
   </author>
   <author>
      <fName>John</fName>
      <lName>Doe</lName>
   </author>
</authors>
return
XQuery ExampleResults
functx:precedes-not-ancestor(
     $in-xml//author[1],$in-xml//author[2])
true
functx:precedes-not-ancestor(
     $in-xml//author[1],
     $in-xml//author[1]/fName)
false
functx:precedes-not-ancestor(
     $in-xml//author[2],$in-xml//author[1])
false

See Also

functx:follows-not-descendantWhether an XML node follows another without being its descendant
functx:first-nodeThe XML node in a sequence that appears first in document order

History

Published OnLast UpdatedContributor(s)
2006-06-272007-02-26W3C XML Query Working Group, XQuery 1.0: An XML Query Language, http://www.w3.org/TR/xquery/(name was changed from precedes to precedes-not-ancestor for clarity)
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