The answer obviously depends on the processor.
With Saxon, if a variable is only referenced once, and the reference isn't in a
loop, then it will be inlined. So if you write
<xsl:variable name="elems" select="key('some', $value, $doc)"
as="element()*"/>
<xsl:for-each select="$elems">
then Saxon will rewrite it as
<xsl:for-each select="key('some', $value, $doc)">
The main benefit of this rewrite is better pipelining. A variable causes the
list of items to be stored somewhere in memory; without the variable, each item
is processed as soon as it is found.
Michael Kay
Saxonica
PS: Saxon 9.1 is about 10 years ago, so my memory of it is rather rusty.
On 26 Sep 2018, at 21:40, Martynas Jusevičius
martynas(_at_)atomgraph(_dot_)com
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
Hi,
I'm using the following pattern in multiple places in my stylesheets:
<xsl:for-each select="key('some', $value, $doc)">
My question is, would iteration be optimized if I selected the nodes
into a variable first?
<xsl:variable name="elems" select="key('some', $value, $doc)"
as="element()*"/>
<xsl:for-each select="$elems">
I guess it should be faster if the key() function is called only once
instead of multiple times? But if there is an index maybe it doesn't
matter?
And does the same apply to
<xsl:apply-templates select="key('some', $value, $doc)"/>
as well?
I'm using Saxon 9.1.0.8.
Martynas
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