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> I start an unrelated topic. How do you implement > xsl:template name="something" and its required > instruction xsl:call-template in the XSLT processor. > i.e. what kind of data structures do you use in Java > and what kind of control flow takes place. Am just > curious since many days.. Depends greatly on the processor. Saxon compiles each template or function into an abstract syntax tree, which is then heavily re-arranged by the optimizer and type-checker, and is then executed interpretively at run-time. A call-template instruction is a node in this tree, containing a pointer to the tree representing the template to be called. Template names aren't used at run-time, they are fully resolved at compile time. You asked about control flow. In Saxon 6.x, and probably in most XSLT 1.0 processors, the XSLT and XPath engines were very separate. In 8.x they have become much more integrated, probably reflecting the influence of XQuery. However Saxon still has two modes of execution internally, pull and push: expressions such as path expressions are usually evaluated by a stack of iterators [expletive deleted] data in a pipeline from the source document, while element and attribute construction instructions are usually evaluated by means of a push pipeline pushing SAX-like events out to the serializer (or the result tree builder if the user requests one). Control instructions such as xsl:if and xsl:call-template can be evaluated in either mode, depending on where they appear. There's also a fairly experimental capability to execute element constructors in pull mode, leading to lazy tree construction, so parts of a temporary tree that aren't ever referenced don't actually get built. If you're interested in understanding such things it would be instructive to read the source code of a processor such as Saxon. It's probably a bit daunting at first, but you'll find it interesting. Michael Kay http://www.saxonica.com/
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