Re: [xsl] Does XSLT have a run-time system?

Subject: Re: [xsl] Does XSLT have a run-time system?
From: Wolfgang Laun <wolfgang.laun@xxxxxxxxx>
Date: Thu, 26 Dec 2013 16:31:49 +0100
See inline.

On 26/12/2013, Costello, Roger L. <costello@xxxxxxxxx> wrote:
> Hi Folks,
> Wikipedia describes "run-time system" like so [1]:
> 	Every computer language implements some form
> 	of runtime system, whether the language is a compiled
> 	language or an interpreted language.
> 	As a simple example of a basic runtime, the runtime
> 	system of the C language is a particular set of instructions
> 	inserted into the executable image by the compiler.
> 	Among other things, these instructions manage the
> 	processor stack, create space for local variables, and
> 	copy function-call parameters onto the top of the stack.
> 	The reason this behavior is part of the runtime, as opposed
> 	to part of a keyword of the language, is that it is systematic,
> 	maintaining the state of the stack throughout a program's
> 	execution. The systematic behavior implements the execution
> 	model of the language, as opposed to implementing semantics
> 	that contribute to a particular computed result.
> From that description,

Which, as it clearly says, it is not - it is an example of same. But
the general idea of a runtime system can, more generally, be described
as the code and data that is required, in addition to some
representation of the program code, to maintain the state of that
program throughout its execution. The term RTS may also include a
library that's called from the representation of the program code, or
interpreting that code.

> run-time doesn't seem to be pertinent to an XSLT
> processor implemented using, say, Java. Those kinds of
> execution-time-inserted instructions would be done by Java (or at a lower
> level), I would think.

This is quibbling. Even if an XSLT processor would compile nothing and
interpret a raw DOM tree representing the XSLT program, there would
still be a RTS. I've never thought about implementing an XSLT
processor ;-) but here's
a few ideas. A RTS could be written in Java code and there would be
Java objects representing the XSLT program, the input documents, the
output documents, the keys, the mode, the program's location, the
stacked set of variables and the parameters, the input document
cursor, certain declarations and whatever. Plenty.


> Does XSLT have a run-time system? If yes, would you give some intuitions
> about what it contains please?
> /Roger
> [1]

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