Re: [xsl] XPath MOD 10 calculation

[Abel Braaksma <abel.online@xxxxxxxxx>]

Well, 'elegant' is in the eye of the beholder, I think ;)

Perhaps this is something that you consider more elegant. But depending 
on your audience, it may win the beauty contest, but not receive praise 
for elegance:

<xsl:variable name="x"
    select="sum(for $i in (1,3,5,7,9,11,2,4,6,8,10) return 
number(substring(., $i, 1))) mod 10" />

and leave the xsl:if as-is. Or you can rewrite your xsl:if like this:

<xsl:if test="(10 - $x) mod 10 ne substring(., 12, 1)" />

which brings us to a possibility to combine the two in one expression 
without repetition:

<xsl:if test="(10 - sum(for $i in (1,3,5,7,9,11,2,4,6,8,10) return 
number(substring(., $i, 1))) mod 10) mod 10 ne substring(., 12, 1)" />


I'm not certain of the order of operator precedence, you may have to 
insert some parentheses here and there. I didn't test it, because I 
don't know the MOD 10 algorithm and you did not provide enough examples 
to really test it. I chose for number() instead of xs:integer because 
sum() takes doubles and xs:integer can fail with an error, where 
number() cannot fail.

Cheers,
-- Abel Braaksma





Jesper Tverskov wrote:
> Hi list
>
> I have made a MOD 10 calculation with XPath to check if a UPC barcode
> number is legal. I am just wondering if the code could be made more
> elegant with some of the new stuff in XPath 2.0.
>
> Since I am going to use the test in Schematron, I can use variables
> but not templates or other xsl elements than shown below.
>
> The context value is some UPC code like 639382000393.
>
> <xsl:variable name="x" select="((xs:integer(substring(., 1, 1)) +
> xs:integer(substring(., 3, 1)) + xs:integer(substring(., 5, 1)) +
> xs:integer(substring(., 7, 1)) + xs:integer(substring(., 9, 1)) +
> xs:integer(substring(., 11, 1))) * 3 + (xs:integer(substring(., 2, 1))
> + xs:integer(substring(., 4, 1)) + xs:integer(substring(., 6, 1)) +
> xs:integer(substring(., 8, 1)) + xs:integer(substring(., 10, 1)))) mod
> 10"/>
>
> <xsl:if test="(if ($x ne 0) then (10 - $x) else $x) ne
> xs:integer(substring(., 12, 1))">
> <!-- Not legal, do something -->
> </xsl:if>
>
> Cheers,
>
> Jesper Tverskov
> http://www.xmlplease.com/xslt