Subject: [xsl] Optimization/error reporting: cardinality checks & function calls From: Frans Englich <frans.englich@xxxxxxxxx> Date: Mon, 23 Jan 2006 17:11:08 +0000 |
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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