24497 2014-02-05 02:19:31 +0000 Missing posture and operands for streamability of xsl:merge 2014-05-15 14:00:28 +0000 1 1 1 Unclassified XPath / XQuery / XSLT XSLT 3.0 Last Call drafts PC Windows NT CLOSED FIXED P2 normal --- 24343 1 abel.braaksma mike cmsmcq public-qt-comments oldest_to_newest 99728 0 abel.braaksma 2014-02-05 02:19:31 +0000 Under 19.8.4.24 Streamability of xsl:merge (http://www.w3.org/TR/xslt-30/#streamability-xsl-merge), the posture is missing. Also, it is not clear what the operands are for xsl:merge-source and whether xsl:merge-key is part of the operands. The current rule seems to indicate that the following is allowed: <xsl:merge> <xsl:merge-source select="." > <xsl:merge-key select="foo" /> </xsl:merge-source> <xsl:merge-action> <xsl:copy-of select="." /> </xsl:merge-action> </xsl:merge> Perhaps a bit senseless, and perhaps potentially streamable (I think it should not be streamable with the current rules), but I think we should at least name the operands. Also, I think we can do better here than only allowing motionless sources. I.e., when the for-each expression is absent or motionless and the select expression is consuming (or the reverse), and the merge-key is motionless, I think xsl:merge is streamable to the extend that merge-action is streamable. We might even go so far to consider xsl:merge streamable if the union of the select-expression is streamable, which would allow: <xsl:merge bind-key="grp"> <xsl:merge-source select="foo"> <xsl:merge-key select="@name" /> </xsl:merge-source> <xsl:merge-source select="bar"> <xsl:merge-key select="@name" /> </xsl:merge-source> <xsl:merge-action> <xsl:value-of select="$grp" /> </xsl:merge-action> </xsl:merge> because the expression "foo | bar" is a streamable pattern, "@name" is motionless and the merge-action is consuming. 100276 1 cmsmcq 2014-02-11 13:49:18 +0000 We discussed this in Prague; the editor agrees that the current treatment is a bit cursory and will come back with a proposal. 100974 2 mike 2014-02-20 17:19:21 +0000 I think we should keep this simple; doing a merge while we are already processing a streamed document is not a use case we need to pursue. So I think the rule should be: * The xsl:merge instruction is grounded and motionless if every xsl:merge-source child element satisfies the following conditions: ** The for-each-item expression, if present, is grounded and motionless ** The for-each-stream expression, if present, is grounded and motionless ** If neither the for-each-item nor for-each-stream attribute is present, then the select expression is grounded and motionless * Otherwise the xsl:merge instruction is roaming and free-ranging. 101837 3 abel.braaksma 2014-03-04 16:15:22 +0000 Independently of each other, we seem to have written down the exact same rules ;), see bug 24343, comment#5, item 6. I agree that we do not need to make the odd case of a merge action on the current streamed document streamable. 102065 4 mike 2014-03-07 15:01:39 +0000 On 2014-03-06 the WG accepted the proposal in comment 2, subject to wording changes to improve readability. The changes have been applied.