Saxon

I think I have found an issue with XSLT 3 streaming and an accumulator using saxon:capture which I understand makes a snapshot() available. Somehow that snapshot doesn't seem to copy another accumulator used (tested with EE 10.5 Java).

Sample code:

<?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:saxon="http://saxon.sf.net/"
    exclude-result-prefixes="#all"
    expand-text="yes">
    
    <xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
    
    <xsl:mode streamable="yes" on-no-match="shallow-skip" use-accumulators="#all"/>
    
    <xsl:accumulator name="header-cats" as="xs:string*" initial-value="()" streamable="yes">
        <xsl:accumulator-rule match="header-items/item/cat/text()" select="$value, string()"/>
    </xsl:accumulator>
    
    <xsl:accumulator name="capture-data" as="element()?" initial-value="()" streamable="yes">
        <xsl:accumulator-rule match="data-items/foo" phase="end" saxon:capture="yes" select="."/>
    </xsl:accumulator>
    
    <xsl:template match="foo">
        <xsl:copy-of select="accumulator-after('capture-data')[not(cat = trace(accumulator-before('header-cats')))]"/>
    </xsl:template>
    
</xsl:stylesheet>

When run against the input sample show below I get the output

*: empty sequence
*: empty sequence
<foo>
   <value>foo 1</value>
   <cat>cat4</cat>
</foo>
<foo>
   <value>foo 2</value>
   <cat>cat2</cat>
</foo>

Input:

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <header-items>
        <item>
            <id>h1</id>
            <cat>cat1</cat>
        </item>
        <item>
            <id>h2</id>
            <cat>cat2</cat>
        </item>
        <item>
            <id>h3</id>
            <cat>cat3</cat>
        </item>
    </header-items>
    <data-items>
        <foo>
            <value>foo 1</value>
            <cat>cat4</cat>
        </foo>
        <foo>
            <value>foo 2</value>
            <cat>cat2</cat>
        </foo>
    </data-items>
</root>

When I use snapshot explicitly, as in

<?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:saxon="http://saxon.sf.net/"
    exclude-result-prefixes="#all"
    expand-text="yes">
    
    <xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
    
    <xsl:mode streamable="yes" on-no-match="shallow-skip" use-accumulators="#all"/>
    
    <xsl:accumulator name="header-cats" as="xs:string*" initial-value="()" streamable="yes">
        <xsl:accumulator-rule match="header-items/item/cat/text()" select="$value, string()"/>
    </xsl:accumulator>
    
    <xsl:template match="foo">
        <xsl:copy-of select="snapshot()[not(cat = trace(accumulator-before('header-cats')))]"/>
    </xsl:template>
    
</xsl:stylesheet>

I get the output

* [1]: xs:string: cat1
* [2]: xs:string: cat2
* [3]: xs:string: cat3
* [1]: xs:string: cat1
* [2]: xs:string: cat2
<foo>
   <value>foo 1</value>
   <cat>cat4</cat>
</foo>

so there the other accumulator header-cats seems to be copied.

I supposed that should also happen for the saxon:capture use.