Saxon

The NPE in LinkedTreeBuilder is caused by the fact that AnalyzeStringFn fails to issue a startContent() call after the first startElement(). This (apparently) causes no problems when a TinyTreeBuilder is used, but in XQuery Update the default is to use a LinkedTreeBuilder and this requires the client to follow the correct protocol.

Having made this change, and running with update:on, I get the message

Overwriting file /Users/mike/bugs/2016/wicentowski/test.xml

As far as I can see, the new file contains the required result.

It's possible that the LinkedTreeBuilder crash also occurred when running in oXygen, and oXygen masked the failure, but before the crash happened the input file had already been opened for writing and therefore the old contents were lost.

The code in 9.6 for the AnalyzeStringFn is completely different from the 9.7 code; we effectively compile the call on fn:analyze-string into a rather complex xsl:analyze-string instruction. This includes a call to a custom ProcessRegexMatchInstruction (which outputs the regex group elements), and the problem seems to be that this has been loop-lifted out of the AnalyzeString instruction that sets its context.

I've prevented the loop-lifting by giving the ProcessRegexMatchInstruction the static property HAS_SIDE_EFFECTS (justified by the fact that it creates new elements). With this change the query runs to completion. The updated file is different from the original in that in the original text

I'm not convinced that the query is producing the required output, however. Further checking needed.

It turned out the 9.6 version test was using -update:discard so it's not surprising the file wasn't updated. When I switch to -update:on, I get a new error:

java.lang.NullPointerException

at net.sf.saxon.tree.linked.NodeImpl.getNamePool(NodeImpl.java:362)

at net.sf.saxon.tree.linked.NodeImpl.getDisplayName(NodeImpl.java:411)

at net.sf.saxon.om.NameOfNode.getDisplayName(NameOfNode.java:54)

at net.sf.saxon.serialize.XMLEmitter.attribute(XMLEmitter.java:411)

at net.sf.saxon.event.ProxyReceiver.attribute(ProxyReceiver.java:166)

at net.sf.saxon.event.TreeReceiver.attribute(TreeReceiver.java:209)

at net.sf.saxon.tree.linked.ElementImpl.copy(ElementImpl.java:344)

This is caused when the updated tree is being serialized to the output file. The crash happens because an attribute node (which must be the rend='italic' node) has a parent element which is not on the tree and which itself has a null parent pointer.

Correction: it's not the attribute being serialized that has the incorrect parent element. The name of the attribute is a NameOfNode() object, and this references a Node in the original tree that has been disconnected from its root, so the link to the NamePool is broken and the name cannot be resolved.

I compared the execution with 9.7, and in 9.7 the name of the attribute node is represented by a FingerprintedQName rather than by a NameOfNode object.

This is because AttributeImpl.copy() in 9.6 calls out.attribute(new NameOfNode(this))@, while 9.7 calls @out.attribute(NameOfNode.makeName(this) - the latter method tests whether the node is mutable before creating a NameOfNode object that wraps it.

I've copied the 9.7 code to 9.6 and it now runs successfully.