XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (425 page)

BOOK: XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition
13.43Mb size Format: txt, pdf, ePub

To see the difference, consider the following source document:


   


      

      

   


   

   


      

      

   



With this document, if the variable
$chapters
contains only the outer

element,
$chapters//diagram[1]
will select diagrams 12, 14, and 15, while both
$chapters/descendant::diagram[1]
and
($chapters//diagram)[1]
will select diagram 12 only.

Combining Sets of Nodes

Until now this chapter has been all about path expressions. This section describes operators that combine two sets of nodes. Although these aren't technically path expressions, they are invariably used in conjunction with path expressions, so it's useful to deal with them at the same time. The operators are:

  • Union, written
    union
    or
    |
    , which includes a node in the result if it is present in either of the two supplied sets, eliminating any duplicates.
  • Intersection, written
    intersect
    , which includes a node in the result if it is in both the two sets.
  • Difference, written
    except
    , which includes a node in the result if it is in the first set and is not in the second.

Other books

The Broken Lands by Kate Milford
A Matter of Sin by Jess Michaels
The Last Free Cat by Blake Jon
Crossing the River by Amy Ragsdale
Leonardo da Vinci by Abraham, Anna
The Prospects by Halayko, Daniel
Terminal Value by Thomas Waite