The section https://www.w3.org/TR/xslt-30/#streamability-fn-accumulator-after of the XSLT 3 spec when detailing the streamability of the accumulator-after function says under point 5:
If the function call is contained in the select expression or contained sequence constructor of an xsl:accumulator-rule specifying phase="end", then it is motionless.
That way I would expect to be able to call that function in an accumulator-rule with phase="end":
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="3.0"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:map="http://www.w3.org/2005/xpath-functions/map"
expand-text="yes"
exclude-result-prefixes="#all">
<xsl:mode streamable="yes" on-no-match="shallow-copy" use-accumulators="#all"/>
<xsl:accumulator name="header-id" streamable="yes" as="xs:integer?" initial-value="()">
<xsl:accumulator-rule match="header-item/id/text()" select="xs:integer(.)"/>
</xsl:accumulator>
<xsl:accumulator name="header-value" streamable="yes" as="xs:string?" initial-value="()">
<xsl:accumulator-rule match="header-item/value/text()" select="string()"/>
</xsl:accumulator>
<xsl:accumulator name="header-map" streamable="yes" as="map(xs:integer, xs:string)" initial-value="map{}">
<xsl:accumulator-rule match="header-item"
phase="end"
select="map:put($value, accumulator-after('header-id'), accumulator-after('header-value'))"/>
</xsl:accumulator>
<xsl:template match="header"/>
<xsl:template match="item/header-ref">
<header-value>{accumulator-before('header-map')(xs:integer(@idref))}</header-value>
</xsl:template>
</xsl:stylesheet>
However, Saxon 9.9.1.2 EE (current latest Saxon 9 EE version available in oXygen) rejects that stylesheet with
The xsl:accumulator-rule/@select expression (or contained sequence constructor) for a streaming accumulator must be grounded and motionless. A call to accumulator-after() is consuming when there are no preceding consuming instructions
Is Saxon not implementing that rule 5 I cited or does it not apply to the above example for some other parts of the spec?
Sample input file would be
<?xml version="1.0" encoding="UTF-8"?>
<root>
<header>
<header-item>
<id>1</id>
<value>header 1</value>
</header-item>
<header-item>
<id>2</id>
<value>header 2</value>
</header-item>
</header>
<body>
<items>
<item>
<id>i1</id>
<header-ref idref="1"/>
</item>
</items>
</body>
</root>
Streamability of accumulator-after in select expression of accumulator-rule with phase=end
RE: Streamability of accumulator-after in select expression of accumulator-rule with phase=end
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Added by Michael Kay over 5 years ago
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