Re: [xsl] streaming XSLT creating a header from a first record

Subject: Re: [xsl] streaming XSLT creating a header from a first record
From: "Geert Bormans geert@xxxxxxxxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 15 May 2018 13:17:46 -0000
still trying to get my head around this and facing obstacles,
most likely by lack of understanding... however

example in

<table>
    <row id="row1" attr1="A" attr2="AA"/>
    <row id="row2"  attr1="C" attr2="CC"/>
    <row id="row3"  attr1="D" attr2="DD"/>
</table>

example out

<document>
    <header>
        <!-- process first row here -->
        <id>row1</id>
        <attr1>A</attr1>
        <attr2>AA</attr2>
    </header>
    <content>
        <!-- process all including first row here -->
        <row id="row1" attr1="A" attr2="AA"/>
        <row id="row2" attr1="C" attr2="CC"/>
        <row id="row3" attr1="D" attr2="DD"/>
    </content>
</document>


Using the accumulator or the xsl:iterate approach allows me to process the
header row twice
but I can't seem to figure out to create the header and then continue the
iteration in a different construct
it seems I need the header always before the iterator has started
Feels close, but no sigar

Thanks

Best regards,

Geert Bormans

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----- Oorspronkelijk bericht -----
Van: "Abel Braaksma, (Exselt) abel@xxxxxxxxxx"
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Aan: "xsl-list" <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Verzonden: Dinsdag 8 mei 2018 20:11:09
Onderwerp: Re: [xsl] streaming XSLT creating a header from a first record

On 08.05.2018 18:04, Michael Kay mike@xxxxxxxxxxxx wrote:
> I don't think you need two accumulators, you can have a single accumulator
that matches every row and only creates the map if the current value is an
empty map.

Taking up that idea I tried also to construct a streaming accumulator
that stores a (shallow) copy of the first row element and a deep copy of
its attributes:

	<xsl:accumulator name="first-row-copy" as="element(row)?"
initial-value="()" streamable="yes">
		<xsl:accumulator-rule match="table/row">
			<xsl:choose>
				<xsl:when test="empty($value)">
					<xsl:copy>
						<xsl:copy-of select="@*"/>
					</xsl:copy>
				</xsl:when>
				<xsl:otherwise>
					<xsl:sequence select="$value"/>
				</xsl:otherwise>
			</xsl:choose>
		</xsl:accumulator-rule>
	</xsl:accumulator>

Seems to also work fine. So in that case one doesn't need to switch
between XML and maps when processing the stored value but can continue
to use the traditional XSLT processing of XML.

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