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Re: [xsl] RE: Is xsl:for-each "syntactic sugar"?

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On 07/05/2010 23:34, Costello, Roger L. wrote:

I do not believe that this task can be accomplished using xsl:for-each.

why not?

> Do you agree?

No.

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="BankTransactions">
<xsl:for-each select="Transaction">
<xsl:value-of select="sum(.|preceding-sibling::*),' '"/>
</xsl:for-each>
</xsl:template>

</xsl:stylesheet>

$ saxon9 rc.xml rc.xsl
<?xml version="1.0" encoding="UTF-8"?>95  92.5  102.5  95

It's (probably, unless Michael rewrites it aggressively behind the scenes) an algorithm with theoretically greater computational complexity than the versions using + (order n squared instead of linear) but it's a lot easier to read and write and unless there are hundreds of siblings the complexity may not matter,


<xsl:if test="following-sibling::Transaction">
<xsl:apply-templates select="following-sibling::Transaction[1]">


the xsl:if isn't needed as if the test is false the apply-templates wouldn't do anything anyway.

As Dimitre has already said, you can't give general advice about which kind of algorithm is superior, it depends a lot on whether the system does tail recursion elimination on the explicitly recursive forms, so like most optimisation questions the answers are system specific.

David

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