"Don't Search For Instructions Until..." statement?

VK · May 28, 2006

Let's say I have a rather big HTML template like

<?xml version="1.0" encoding="ISO-8859-1"?>
....
<snip>
....
<xsl:template match="/">
<html>

<xsl:for-each select="repository/item">

</xsl:for-each>
....
</html>
</xsl:template>
</xsl:transform>

If I understand properly, XSL will still study each line after
<xsl:template match="/"> for XSL command wasting its time. Is there a
way to start output (thus use
<xsl:template match="/">) but postpone XSL parsing until some
predefined sequence? Namely I'm thinking of some kind of Perl
equivalent of single-quote print block like
print <<'EOT'
....
EOT

Joe Kesselman · May 30, 2006

VK said:
If I understand properly, XSL will still study each line after
<xsl:template match="/"> for XSL command wasting its time.

I suspect that isn't going to take a significant amount of time, but if
you insist on trying to avoid it -- move some of the literal content out
of the template into a stylesheet variable, and just insert its value.

Alternatively, switch to a compiled stylesheet system such as Xalan's
XSLTC support, which will probably optimize this automagically without
your having to do anything to the stylesheet.

Andy Dingley · May 30, 2006

VK said:
If I understand properly, XSL will still study each line after
<xsl:template match="/"> for XSL command wasting its time.

Yes, it's called "parsing".

In practice, parsing is typically the slowest part of building
server-side web output when loading a new stylesheet each time. So look
at an XSLT transform engine that allows you to cache this after loading
and re-use the same stylesheet next time. It's a useful saving.

Joe Kesselman · May 30, 2006

Andy Dingley said:
at an XSLT transform engine that allows you to cache this after loading
and re-use the same stylesheet next time. It's a useful saving.

Note that the TrAX APIs support this -- you can load a stylesheet once
(which is when stylesheet parsing generally occurs) and then invoke it
multiple times.

VK · May 31, 2006

Joe said:
Note that the TrAX APIs support this -- you can load a stylesheet once
(which is when stylesheet parsing generally occurs) and then invoke it
multiple times.

Thanks to both of you.

Does enclosing non-XSL part of template into <xsl:text>...</xsl:text>
have an effect on parsing (speed)? Would be glad to be pointed to some
specs/test results.

Joe Kesselman · May 31, 2006

VK said:
Does enclosing non-XSL part of template into <xsl:text>...</xsl:text>
have an effect on parsing (speed)?

I wouldn't expect xsl:text to make much difference in stylesheet
parse-and-interpret-or-compile speed.

Note that you can't use xsl:text to escape literal result elements; as
its name implies it's intended to give more explicit control over the
boundaries of character content.

I strongly suspect you're micro-optimizing the wrong part of your
problem. Have you run a performance analysis to find out where your
system is actually spending its time? As with any programming language,
rewriting a stylesheet can sometimes tremendously improve its performance.

VK · May 31, 2006

Joe said:
I wouldn't expect xsl:text to make much difference in stylesheet
parse-and-interpret-or-compile speed.

ACK - but I'll still check with timers.

Note that you can't use xsl:text to escape literal result elements; as
its name implies it's intended to give more explicit control over the
boundaries of character content.
ACK

I strongly suspect you're micro-optimizing the wrong part of your
problem.

Actually I don't have any performance problems right at this moment.
I'm just thinking of some common technics (of they exists) for
optimisation of non-XSL part of templates.

Joe Kesselman · Jun 1, 2006

VK said:
Actually I don't have any performance problems right at this moment.
I'm just thinking of some common technics (of they exists) for
optimisation of non-XSL part of templates.

The best ways to optimize those are to do so inside the XSLT processor
(a) compile the stylesheet, and (b) while you're at it, prepare blocks
of literal output so they can be dumped out relatively quickly.

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"Don't Search For Instructions Until..." statement?

VK

Joe Kesselman

Andy Dingley

Joe Kesselman

VK

Joe Kesselman

VK

Joe Kesselman

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