Subject: Re: [xsl] Optimization/error reporting: cardinality checks & function calls From: Dimitre Novatchev <dnovatchev@xxxxxxxxx> Date: Tue, 24 Jan 2006 06:59:34 +1100 |
> I think the understanding is meant to be that an implementation is free to > skip "evaluation" of an argument, and that the cardinality check is also free > to be skipped if the argument as a whole has been skipped. > > Am I right in my interpretation? It seems to me that the return type of the function cannot be determined without knowing the cardinality of the function -- due to the fact that different overloads can have different return types. Therefore, as cardinality would be necessary in general, it cannot be skipped or ignored. -- Cheers, Dimitre Novatchev --------------------------------------- To avoid situations in which you might make mistakes may be the biggest mistake of all. On 1/24/06, Frans Englich <frans.englich@xxxxxxxxx> wrote: > > Hi all, > > I'm a bit confused about errors & optimizations in XPath/XQuery > implementations, perhaps someone could help me clear it. > > 2.3.4 Errors and Optimization in XML Path Language (XPath) 2.0 says that > implementations are free to perform arbitrary optimizations(such as skipping > evaluation of somekind) as long as 1) The result is identical to when not > being optimized, except for that errors are possibly not reported; and 2) > that cardinality errors are still reported. > > Section 2.3.4 uses the term "expression", and I presume functions are > applicable to that discussion(functions are expressions). > > Further, in 3.1.5 Function Calls, one can read this: > > <quote> > Argument expressions are evaluated, producing argument values. The order of > argument evaluation is implementation-dependent and a function need not > evaluate an argument if the function can evaluate its body without evaluating > that argument. > </quote> > > I think the understanding is meant to be that an implementation is free to > skip "evaluation" of an argument, and that the cardinality check is also free > to be skipped if the argument as a whole has been skipped. > > Am I right in my interpretation? > > > Cheers, > > Frans
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