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Re: [xsl] accumulators

2013-04-20 11:41:17
Like xsl:key, accumulators apply to every document, but when you evaluate the 
accumulator function, you get the value applicable to the context node. In all 
your calls of the accumulator function, the context node is the root of the 
principal source document.

Accumulators are strictly functional: the value is a function of the context 
node. If you call the function twice and the context node is the same for both 
calls, you will get the same answer.

Michael Kay
Saxonica


On 19 Apr 2013, at 22:04, Jakub Malý wrote:

Hi, 
I am fiddling with XSLT accumulators in the new version of Saxon. 
I first looked at the examples in the spec and thought that this might work
(and output 01210), but it doesn't:

<?xml version="1.0" encoding="UTF-8"?>

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
      xmlns:f="myf"   version="3.0">

      <xsl:accumulator name="f:my-var" as="xs:integer" initial-value="0" >
              <xsl:accumulator-rule match="f:inc" new-value="$value + 1"/>
              <xsl:accumulator-rule match="f:dec" new-value="$value - 1"/>
      </xsl:accumulator>
      
      <xsl:variable name="f:control-inc" as="element()*">
              <f:inc/>
      </xsl:variable>
      <xsl:variable name="f:control-dec" as="element()*">
              <f:dec/>
      </xsl:variable>
      
      <xsl:template match="/">
              <xsl:value-of select="f:my-var()" />
              <xsl:apply-templates select="$f:control-inc"/>
              <xsl:value-of select="f:my-var()" />
              <xsl:apply-templates select="$f:control-inc"/>
              <xsl:value-of select="f:my-var()" />
              <xsl:apply-templates select="$f:control-dec"/>
              <xsl:value-of select="f:my-var()" />
              <xsl:apply-templates select="$f:control-dec"/>
              <xsl:value-of select="f:my-var()" />
      </xsl:template>
</xsl:stylesheet>

So I read the spec and I guess I understand why. 
Accumulator rule is not triggered by calling apply-templates, it does not
matter how many times the same node is processed, the value for the
accumulator will be the same. 

Do accumulators work only for the nodes from the source document or also for
nodes from documents loaded using doc() or document()?  

Jakub.



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