Re: [xsl] Using "except" where some nodes are copies (not the original)?

[Michael Kay <mike@xxxxxxxxxxxx>]

replace ($X except $Y) by

$X[not(some $y in $Y satisfies deep-equal(., $y))]

It's likely to be an expensive operation.

Michael Kay
Saxonica


On 28/12/2011 23:17, Costello, Roger L. wrote:
> Hi Folks,
>
> How do I do set subtraction where some of the nodes in the two sets may be copies (not originals)?
>
> Please allow me to explain.
>
> Consider this XML document:
>
> <Test>
>      <A/>
>      <B/>
>      <C/>
> </Test>
>
> Set<Test>  as the context node.
>
> This operation:
>
>      (A, B,, C) except (B, C)
>
> returns:
>
>      (A)
>
> Nice.
>
> Now, make a copy of B and store it into a variable:
>
>        <xsl:variable name="B" as="element(B)">
>                  <xsl:copy-of select="B" />
>         </xsl:variable>
>
> Run the same operation, but using the variable:
>
>      (A, B, C) except ($B, C)
>
> Returns:
>
>      (A, B)
>
> Ouch!
>
>   I don't want that behavior. I want:
>
>      (A, B, C) except ($B, C)
>
> to return:
>
>      (A)
>
> How do I achieve the behavior I desire?
>
> That is, how do I do set subtraction where some of the nodes in the two sets may be copies?
>
> /Roger