David Bertoni wrote / napísal(a):
Tomas Studva wrote:
Xalan-C does not rely on recursion and the processor stack to execute
stylesheets. Instead, it simply walks the stylesheet tree
iteratively, figuring out what needs to be executed next. If it does
need to save some small bit of context, it does that on a "stack"
that's kept in dynamically allocated memory.
This has a number of advantages:
1. There's a much smaller chance that stylesheet execution will
consume the entire processor stack.
2. Because there is only a small amount of context to be saved, and
it's not saved all of the time, execution is faster and consumes less
memory. For example, just the overhead of the C++ stack frame is often
greater than than any local context that needs to be saved.
3. Execution can be interrupted at any time by simply breaking out of
a loop, rather than unwinding a large number of stack frames.
4. It's trivial to restart execution at the point it was interrupted
by just re-entering the loop starting with the last template executed.
I'm not sure what you mean by "incremental," because I don't see how
it relates to the data model, unless you mean building the source tree
incrementally, which is a very different thing from executing the
transformation incrementally.
Dave
I understand, iterative execution. No I don't mean incremental in a way
of reading source incrementally, what is usable for big size sources in
databases. I mean what you get when you type "incremental xslt" in
google. Or look at
http://tstudva.googlepages.com/darwin-anincrementalxsltprocessor or in
design of Darwin
http://www.javaforge.com/proj/doc/details.do?doc_id=36525. I don't
understand Xalan execution in details and that is problem for me. Some
good documentation would help. On Xalan page in design doc, there is
written, transformation is performed mainly in transform package. There
is transformer, the main class, and there is performed iterative
execution using self(on heap) managed stacks. But some part of
execution is performed in ElemTemplatesElement, so I am confused. My
second big question is if I choosed good to start with Xalan trunk and
not with any branch.
