RE: XSLT processor

> 
> What an XSLT processor do?

An XSLT processor converts a source tree to a result tree under the
control of a stylesheet.
> 
> Does XSLT processor use XML parser to parse XSL
> statements?

Yes, the first thing an XSLT processor does is to invoke an XML parser
to parse the source stylesheet.

There is a little bit of ambiguity in the 1.0 spec about whether the XML
parsing is done within the XSLT processor or outside it, but this is an
academic detail. Most implementations will allow you to supply the
stylesheet in either source XML or parsed form (e.g. as a DOM).


> I mean I think there are two scenarios for XSL
> statements processing:
> 1)XSLT processors have their own parser to parse
> statements
> 2)They use XML parsers to parse XSL stataments and
> then walk on the DOM tree generated by the XML parser
> to find the XSL expressions.Process these expressions
> and modify this tree according to this statements
> 
> I think the second one is more realistic.
> Am I right? If someone can explain what XSLT exactly
> does, I would be grateful

As far as I know most XSLT processors use an off-the-shelf XML parser to
parse both the source documents and the stylesheets, though there have
been some attempts at integration, for example Xalan and Xerces have a
fairly intimate relationship.
> 
> And lastly, what kind of tree(or any other data
> structure) is used by XPath to store XML nodes?

This is an internal detail of the design of the processor. 

For Saxon, the article at
http://www-106.ibm.com/developerworks/xml/library/x-xslt2/?dwzone=xml
might give you a better understanding of the internals.

Michael Kay


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