Re: [xsl] Slow XSLT

[Cleyton Jordan <cleytonjordan@xxxxxxxxxxx>]

Hi,

--- Manfred Staudinger <manfred.staudinger@xxxxxxxxx>
wrote:
> - see Michael Kay:
>   
>
http://www.ibm.com/developerworks/xml/library/x-xslt/
> Manfred

I am reading one of the articles that Manfred has
suggested (Michael Kay: What kind of language is
XSLT?) so that I can learn more about using node sets,
apply templates and recursion but I do not fully
understand some of the XPATH expressions.

I would appreciate your help in understanding the
expressions below:

Given this XML (as per the Michael Kay's article):
________________


<results group="A">
<match>
    <date>10-Jun-1998</date>
    <team score="2">Brazil</team>
    <team score="1">Scotland</team>
</match>
<match>
    <date>10-Jun-1998</date>
    <team score="2">Morocco</team>
    <team score="2">Norway</team>
</match>
<match>
    <date>23-Jun-1998</date>
    <team score="1">Brazil</team>
    <team score="2">Norway</team>
</match>
</results>


These are the expressions used to compute the teams
standings:

1 - <xsl:variable name="teams"
select="//team[not(.=preceding::team)]"/>

I know that this expression is getting a node set of
all the unique team elements.

I am confused about the "." (dot) in this expression
and the comparisson with the preceding::team.

For the first team, does the "." (dot) match the value
of the node - 'Brazil' - and preceding::team match the
value as well?

select="//team[not('Brazil'=preceding::'Brazil')]"/>

or "." and preceding::team match the wholde node? 

What are we comparing here the element value or the
whole team element?

+++++++

2 - Here we are inside a loop
<xsl:template match="results">
  <xsl:for-each select="$teams">
    <xsl:variable name="this" select="."/>

Again does "." match the value of each team or the
whole team element?


3 - <xsl:variable name="played"
select="count($matches[team=$this])"/>

Now we are computing how many times a particular team
has played.

count($matches[team=$this])

When you use this predicate [team=$this] are we
comparing the value of the element or the team
elements ? 

4 - <xsl:variable name="won"
select="count($matches[team[.=$this]/@score &gt;
team[.!=$this]/@score])"/>

I know that this expression is computing the victories
of a particular team. However, I do not understand the
logic of the expression. We have an extra predicate:
 
[team[.=$this]/@score 

Why cant we just use [team=$this]/@score ?


+++++++++++++++

5 - <xsl:variable name="for"
select="sum($matches/team[.=current()]/@score)"/>

What does current() mean in here? Is it the same as
the $this variable? 

In this case we are not using a predicate for the
$matches variable. why? 

$matches/team

$matches/team[.=current()]/@score)


Thanks for you help.

Cheers

C 




		
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