Re: Spurious error on recursive invocation of fn:transform

Thanks, I've reproduced the problem. As expected, it's all to do with base URIs.

I haven't got to the bottom of it yet, but I think the heart of the issue is that <xsl:copy> is creating a document whose base URI is defined to be the same as the stylesheet URI, and then we are using this URI as a key into the document cache for a call on doc(). Which ignores the fact that multiple documents can have the same base URI: the base URI is not a unique identifier for a document. Unfortunately the JAXP interfaces like the Source object and the URIResolver use a single property (systemId) to represent both base URIs and unique document URIs, so it's easy to get them mixed up.

Michael Kay
Saxonica

> On 24 Nov 2020, at 14:57, Ihe Onwuka <[email protected]> wrote:
> 
> 
> On Tue, Nov 24, 2020 at 7:32 AM Michael Kay <mike-JkSD5nQpfvpWk0Htik3J/[email protected] <mailto:mike-JkSD5nQpfvpWk0Htik3J/[email protected]>> wrote:
>> 
>> The usage of doc('') is not the causation here 
>> 
>> stylesheet-node : doc('fullpathToTheStylesheetAsGeneratedWithdocument-uri/myStylesheet.xsl')
>> 
>> the exact same result.
>>  
> 
> It's not so much the use of doc(""), as the reliance on preservation of a base URI.
> 
> Having said that, if you can put together a repro we'll be happy to look at it. I think it's fairly clear the problem is happening because the base URI is being lost through the call on fn:transform(), but whether losing it is a bug or an application error is something we can only determine if we study the detail.
> 
> Michael Kay
> Saxonica
> 
> Here. 
> 
> Here is bug.xsl
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform <http://www.w3.org/1999/XSL/Transform>"
>                 xmlns:fn="http://www.w3.org/2005/xpath-functions <http://www.w3.org/2005/xpath-functions>"
>        xmlns:xs="http://www.w3.org/2001/XMLSchema <http://www.w3.org/2001/XMLSchema>"
>        xmlns:local="urn:local"
> version="3.0" >
>   
>    <xsl:mode on-no-match="shallow-copy"/>
>    <xsl:function name="local:generateNextVersion" as="document-node()">
>       <xsl:param name="currentVersion" as="document-node()"/>
>       <xsl:variable name="isFinalVersion" as="xs:boolean" select="$currentVersion/* eq '3'"/>
>       <xsl:sequence select="if ($isFinalVersion)
>                             then $currentVersion
>                             else local:generateNextVersion(fn:transform(map { 
>                                                                      'stylesheet-node' : doc(''),
>                                                     'source-node'     :  $currentVersion
>                                                             })?output)"/> 
>    </xsl:function>
> 
>    <xsl:template match="*"> 
>   <xsl:message select="."/>
>       <xsl:copy>	  
>          <xsl:sequence select="let $customizedResult := fn:transform(map {
>                                                               'stylesheet-node' :  doc('bugs2.xsl'),
>                                                               'source-node'     :  /
>                                                                })?output 
>                                return  local:generateNextVersion($customizedResult)"/> 
>        </xsl:copy>
>    </xsl:template>
> 
>  </xsl:stylesheet>
> 
> Here is bugs2.xsl
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform <http://www.w3.org/1999/XSL/Transform>"
>                 xmlns:fn="http://www.w3.org/2005/xpath-functions <http://www.w3.org/2005/xpath-functions>"
> version="3.0" >
>   
>    <xsl:mode on-no-match="shallow-copy"/>
>    <xsl:template match="*">
>       <xsl:copy>
>          <xsl:value-of select=". + 1"/>	     
>       </xsl:copy>
>    </xsl:template>
> 
>  </xsl:stylesheet>
> 
> Here is input XML
> 
> <bug>1</bug>
> 
> Reproduction instructions. 
> 
> Run the transform bug.xsl against input bug.xml and see the xsl:message output below
> 
> <bug>1</bug>
> <bug>2</bug>
> 
> Change bug.xsl to test for $currentVersion eq '4' instead of 3
> 
> crashes as below
> 
> <bug>1</bug>
> <bug>2</bug>
> Error in bugs2.xsl:
>   XTSE0150  The supplied file does not appear to be a stylesheet
> Static error in bugs2.xsl:
>   XTSE0150  The supplied file does not appear to be a stylesheet
> Error in bugs2.xsl:
>   XTSE0150  The supplied file does not appear to be a stylesheet
> at function local:generateNextVersion in bug.xsl:
>      invoked by function call
>   In template rule with match="*" of bug.xsl
>      invoked by built-in template rule (shallow-copy)
> The supplied file does not appear to be a stylesheet
> 
> 
> 
> 
>

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