On Friday 12 April 2002 21:55, Dietrich Ayala wrote:
> Now, in this template, the source tree context node is still the root
> (/doc[1]), right? So how does this match anything, as the match expression
> seems like it would match any "doc" children of the context node?
>
> <xsl:template match="doc/title">
>   <h1>
>     <xsl:apply-templates/>
>   </h1>
> </xsl:template>
>
> I think I'll stop there. Because if my understanding of how the initial
> context node and source-tree-nodes-to-be-processed are flawed, then it only
> goes downhill from here :)

The reason it works is because there is a different between *match* 
expressions and *select* expressions.  In match expressions (template 
match="..."), the context node does not affect the result.  Here, 
match="doc/title" simply means to match <title> elements that are immediate 
children of a <doc> element, regardless of what the current context is.  Once 
the <title> is matched, the <title> becomes the context node within the 
template; the "doc/" is only a restriction on which <title>s can be matched.

Think of match expressions as going in reverse.  Here are the basic steps:

* apply-templates selects a <title> node (as a child of the context node).
* The template tries to match "title" to the selected node.  So far so good.
* The template looks to see if the <title> also has a <doc> parent.  So far so 
good.
* Everything has matched successfully, so the template executes with the 
<title> as the context node.

On the other hand, in expressions like in
<xsl:apply-templates select="child::node()"/> (the equivilant of what you 
have), are relative to the context node, as you know.  But this only selects 
the nodes; the act of matching them to a template is a totally different 
process (read the XPath spec; these two types of expressions even have 
different grammars, although they are very similar).

-- 
Peter Davis

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