11372 2010-11-22 10:08:44 +0000 [XSLT 3.0] (11 May 2010), Section 15.3: Merge-source default context 2012-03-08 18:25:46 +0000 1 1 1 Unclassified XPath / XQuery / XSLT XSLT 3.0 Working drafts PC Linux CLOSED FIXED P2 normal --- 1 oneil mike public-qt-comments oldest_to_newest 42687 0 oneil 2010-11-22 10:08:44 +0000 In Section 15.3, and the second paragraph we observe 'if the select attribute is omitted, the default value is ., which selects the context item'. There is a potential problem here if the merge instruction, say is written in an xsl:function, which has no context item passed in, then the xsl:merge-source context item will be undefined. For example, in the following function 's:merge1' we have an xsl:merge instruction which has a xsl:merge-source, with the select attribute omitted. For the xsl:merge-key the value of the select is ., this will error as xsl:merge-source does not have a valid context item: ... <xsl:function name="s:merge1"> <xsl:merge> <xsl:merge-source> <xsl:merge-input> <xsl:perform-sort select="doc('europe.xml')/europe/country"> <xsl:sort select="." order="ascending"/> </xsl:perform-sort> <xsl:merge-key select="."/> </xsl:merge-input> </xsl:merge-source> <xsl:merge-action> <out> <xsl:value-of select="."/> </out> </xsl:merge-action> </xsl:merge> </xsl:function> ... 49358 1 mike 2011-06-08 22:09:02 +0000 I took an action at the Prague F2F to propose a solution to this one. It's surprisingly difficult, and I think the reason is that the merge-source/merge-input syntax and semantics are pretty dense. Having the two "select" attributes in a one-to-one relationship with each other is particularly confusing. I think we could do better if we refactored it. I would like to propose collapsing xsl:merge-source and xsl:merge-input into a single element with the syntax <xsl:merge-input name = qname for-each = expression select = expression > If for-each is present then the merge-input selects multiple input sequences, one for each anchor item selected by the for-each expression, which is used as the context item for evaluating the select expression. If for-each is absent then the merge-input selects a single input sequence, obtained by evaluating the select expression, which is then evaluated using the context of the merge-input instruction itself. The select expression can be replaced by a contained sequence constructor; the for-each expression can't. I think this will make it much clearer what's going on. 64232 2 mike 2012-02-17 14:50:30 +0000 After considering various alternatives the WG began to find the proposal in comment #1 attractive and gave the editor an action to propose detailed text. 65145 3 mike 2012-03-08 18:25:25 +0000 The WG reviewed the text in the editor's draft of the specification and approved it. Note that the sequence constructor option of the xsl:merge-source element has now disappeared; the main use case for it was to contain an xsl:perform-sort instruction, and the need for this has been removed by adding the attribute sort-before-merge="yes|no" with the default "no".