30033 2016-12-15 12:58:46 +0000 [xslt30] Streamability rules for fn:current() lack an "otherwise" clause 2017-01-05 22:10:48 +0000 1 1 1 Unclassified XPath / XQuery / XSLT XSLT 3.0 Candidate Recommendation PC All RESOLVED FIXED P2 normal --- 1 mike mike public-qt-comments oldest_to_newest 128323 0 mike 2016-12-15 12:58:46 +0000 In section 19.8.9.3, Streamability of the current() function, there's no statement as to what the outcome is if none of the conditions in rules 1, 2, or 3 apply. 128324 1 mike 2016-12-15 14:43:06 +0000 Note also that rule (1) talks of the outermost containing XPath expression, which doesn't really allow for use of current() within a pattern. Test case stream-200 (in test set source-document) uses the following within a streamable accumulator: match="part-name/text()[$selected-parts = current()]" To establish that this is streamable, we need to establish that the static type of current() is a text node. There is nothing in the static typing rules to achieve this. We can make it guaranteed-streamable by writing it as match="part-name/text()[$selected-parts = current() treat as text()]" but this seems a little unfortunate. 128326 2 mike 2016-12-16 10:44:17 +0000 Proposed resolution: Explanations in "[]", which may become notes in the spec if appropriate. (1) Add special rules for the static type of a call to current(): (a) if the call is within an XPath expression, the *context item type* that applies to the outermost containing XPath expression, determined by the rules in 19.2. (b) if the call is within a pattern, the *match type* of the pattern, as defined in 19.2. [Note: a call to current() in a pattern will always be within a predicate, which means that the match type of the pattern will never depend on the static type of the call to current(), so there is no circularity in this definition]. In 19.8.9.3, Streamability of fn:current(), change the rules to (§§ marks changes): The sweep and posture of a call to the current function are determined as follows: §§1. If the call appears within a pattern [Note: it will always be within a predicate of the pattern], then climbing and motionless. 2. Otherwise, let E be the outermost containing XPath expression of the call to the current function. 2(a) If the context posture of E is grounded, then motionless and grounded. 2(b) If the path in the expression tree that connects the call on current to E (excluding E itself) contains an expression that is a higher-order operand of its parent expression, then climbing and motionless. §§2(c) Otherwise, the posture is the context posture, and the sweep is motionless. 128348 3 mike 2017-01-05 22:10:48 +0000 The changes were agreed and have been applied.