Thanks a lot for sharing and helping, Martin, your information is so 
valuable, I'll carefully study your code.



Martin Honnen ha scritto:
> Ebenezer wrote:
>> Let's suppose I have some nodes in an XML file, with an URL attribute:
>>
>> <node url="mypage.php?name1=value1&foo=bar&foo2=bar2&name2=value0" />
>> <node 
>> url="myotherpage.php?name4=value4&foo=bar3&foo2=bar5&name2=value8" />
>>
>> and so on.
>>
>> Let's suppose I want to retrieve this @url parameter, BUT ONLY with 
>> the values, in querystring, associated with "foo" and "foo2" (thus 
>> discarding name1, name2, name4 and every other different ones).
>>
>> In other words, I must obtain:
>>
>> mypage.php?foo=bar&foo2=bar2
>> myotherpage.php?&foo=bar3&foo2=bar5
>> ... and so on.
>>
>> Is there a convenient way, in a transformation with XSL, to obtain 
>> this string manipulation? (I'd prefer to stick to XSLT1.0, if possible)
> 
> Well
>   substring-before(node/@url, '?')
> would give you the file name, the query string would need to be parsed 
> which needs a recursive template or an extension function in XSLT 1.0. 
> In XSLT 2.0 you could use the tokenize function and/or xsl:analyze-string:
> 
> <xsl:stylesheet
>   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>   xmlns:xsd="http://www.w3.org/2001/XMLSchema"
>   xmlns:mf="http://example.com/2008/mf"
>   exclude-result-prefixes="xsd mf"
>   version="2.0">
> 
>   <xsl:function name="mf:get-query" as="xsd:string">
>     <xsl:param name="qs" as="xsd:string"/>
>     <xsl:param name="params" as="xsd:string*"/>
>     <xsl:variable name="filtered-qs" as="xsd:string*">
>       <xsl:for-each select="tokenize($qs, '&amp;')">
>         <xsl:analyze-string
>           select="."
>           regex="({string-join($params, '|')})=\w*">
>           <xsl:matching-substring>
>             <xsl:sequence select="regex-group(0)"/>
>           </xsl:matching-substring>
>         </xsl:analyze-string>
>       </xsl:for-each>
>     </xsl:variable>
>     <xsl:sequence select="string-join($filtered-qs, '&amp;')"/>
>   </xsl:function>
> 
>   <xsl:template match="node">
>     <xsl:value-of select="concat(substring-before(@url, '?'), '?', 
> mf:get-query(substring-after(@url, '?'), ('foo', 'foo2')))"/>
>   </xsl:template>
> 
> </xsl:stylesheet>
> 
>