Selecting siblings between two nodes using XPath

Question

How would I select all the tables between the table whose id is header_completed and the first table after the header_completed one that has an align of center? Here is the

Answer 1

Use the Kayessian method of node-set intersection:

The intersection of two node-sets $ns1 and $ns2 is evaluated by the following XPath expression:

$ns1[count(.| $ns2)=count($ns2)]

If we have the following XML document:

then according to the question, we have:

$ns1 is:

/*/*[@class='header_completed'][1]
                     /following-sibling::*

$ns2 is:

/*/*[@class='header_completed'][1]
             /following-sibling::*[@align='center'][1]
                   /preceding-sibling::*

We simply substitute $ns1 and $ns2 in the Kayessian formula and get the following XPath expression, which selects exactly the wanted 5 elements:

/*/*[@class='header_completed'][1]
                         /following-sibling::*
              [count(.|/*/*[@class='header_completed'][1]
                            /following-sibling::*[@align='center'][1]
                               /preceding-sibling::*)
              =
               count(/*/*[@class='header_completed'][1]
                            /following-sibling::*[@align='center'][1]
                                /preceding-sibling::*)
              ]

To verify that this is really the solution, we use this XSLT transformation:

When this transformation is applied on the XML document above, the wanted correct result is produced:

XPath 2.0 solution:
In XPath 2.0 we can use the intersect operator and the >> and/or the << operators.
The XPath 2.0 expression that corresponds to the previously used XPath 1.0 expression is:
     /*/*[ .
        >>
         /*/*[@class='header_completed'][1]
         ]

  intersect

    /*/*[ /*/*[@class='header_completed'][1]
                 /following-sibling::*[@align='center'][1]
             >>
              .
        ]
Here is an XSLT 2.0 solution, proving the correctness of this XSLT 2.0 expression:

 

 

    

 
   
  
   
 

when applied on the XML document defined before, we again get the same wanted, correct result:


                                                        

              
                
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