Re: [xsl] Slow XSLT

["Andrew Welch" <andrew.j.welch@xxxxxxxxx>]

On 07/03/2008, Cleyton Jordan <cleytonjordan@xxxxxxxxxxx> wrote:
>  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?

. is the string value, so 'Brazil'

The preceding axis contains all nodes before the current node in
document order, not including the current node - so for the first
<team> it would return nothing.

>  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?

. is the string value of the current node, not the element itself


>  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 ?

the string value of elements are compared


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

because the score attribute is on the team element:

$matches[team=$this]/@score

would return the score attribute of the element in $matches if the
predicate evaluated to true

$matches[team[.=$this]/@score

returns the score attribute of the team element is the predicate
evaluated to true


>  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?

current() returns the node that was the context node outside of the
xpath...  when you do $matches/team the context node is changed to the
team element in $matches, the current() function will return what was
context node before you changed it.


-- 
Andrew Welch
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/