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Bug #4578
closedNullPointerException when array:fold-left|right $zero argument is an empty sequence
100%
Description
Following xslt gives an error:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:array="http://www.w3.org/2005/xpath-functions/array"
exclude-result-prefixes="xs array">
<xsl:template match="/">
<xsl:sequence select="
array:fold-left
(
[8, 9],
(),
function($first as item(), $second as item())
{
min(($first, $second))
}
)"/>
</xsl:template>
</xsl:stylesheet>
java.lang.NullPointerException
at net.sf.saxon.functions.hof.CoercedFunction.call(CoercedFunction.java:151)
at net.sf.saxon.functions.SystemFunction.dynamicCall(SystemFunction.java:454)
at net.sf.saxon.ma.arrays.ArrayFunctionSet$ArrayFoldLeft.call(ArrayFunctionSet.java:269)
at net.sf.saxon.expr.FunctionCall.iterate(FunctionCall.java:543)
at net.sf.saxon.expr.Expression.process(Expression.java:949)
at net.sf.saxon.expr.SystemFunctionCall.process(SystemFunctionCall.java:476)
at net.sf.saxon.expr.instruct.TemplateRule.applyLeavingTail(TemplateRule.java:376)
at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:555)
at net.sf.saxon.trans.XsltController.applyTemplates(XsltController.java:659)
at net.sf.saxon.s9api.AbstractXsltTransformer.applyTemplatesToSource(AbstractXsltTransformer.java:360)
at net.sf.saxon.s9api.Xslt30Transformer.applyTemplates(Xslt30Transformer.java:285)
at net.sf.saxon.Transform.processFile(Transform.java:1313)
at net.sf.saxon.Transform.doTransform(Transform.java:853)
at net.sf.saxon.Transform.main(Transform.java:82)
java.lang.RuntimeException: Internal error evaluating template rule at line 7 in module file:/C:/projects/git/xslt-graph/tests/saxon-10.1-internal-error.xslt
at net.sf.saxon.expr.instruct.TemplateRule.applyLeavingTail(TemplateRule.java:393)
at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:555)
at net.sf.saxon.trans.XsltController.applyTemplates(XsltController.java:659)
at net.sf.saxon.s9api.AbstractXsltTransformer.applyTemplatesToSource(AbstractXsltTransformer.java:360)
at net.sf.saxon.s9api.Xslt30Transformer.applyTemplates(Xslt30Transformer.java:285)
at net.sf.saxon.Transform.processFile(Transform.java:1313)
at net.sf.saxon.Transform.doTransform(Transform.java:853)
at net.sf.saxon.Transform.main(Transform.java:82)
Caused by: java.lang.NullPointerException
at net.sf.saxon.functions.hof.CoercedFunction.call(CoercedFunction.java:151)
at net.sf.saxon.functions.SystemFunction.dynamicCall(SystemFunction.java:454)
at net.sf.saxon.ma.arrays.ArrayFunctionSet$ArrayFoldLeft.call(ArrayFunctionSet.java:269)
at net.sf.saxon.expr.FunctionCall.iterate(FunctionCall.java:543)
at net.sf.saxon.expr.Expression.process(Expression.java:949)
at net.sf.saxon.expr.SystemFunctionCall.process(SystemFunctionCall.java:476)
at net.sf.saxon.expr.instruct.TemplateRule.applyLeavingTail(TemplateRule.java:376)
... 7 more
Updated by Vladimir Nesterovsky over 4 years ago
This produces NPE but with different message:
<xsl:sequence select="
array:fold-left
(
[8, 9],
(),
function($first, $second) { min(($first, $second)) }
)"/>
Exception in thread "main" java.lang.AssertionError:
Internal error: no value for variable $first at line 17 of file:/C:/projects/git/xslt-graph/tests/saxon-10.1-internal-error.xslt
Updated by Michael Kay over 4 years ago
- Subject changed from saxon-10.1-internal-error.xslt to NullPointerException when array:fold-left|right $zero argument is an empty sequence
- Category set to XPath conformance
- Assignee set to Michael Kay
- Priority changed from Low to Normal
- Applies to branch 9.9 added
Saxon throws a NullPointerException if the second argument ($zero) of array:fold-left or array:fold-right is an empty sequence.
Further, if the value of the $zero argument is a sequence containing two or more items, all but the first items are ignored.
Added test cases to the relevant test sets in QT3.
Updated by Vladimir Nesterovsky over 4 years ago
If I correctly understand, the problem was to some extent related to eager evaluation of $zero parameter in array:fold-left(), and to some expectations about its cardinality.
This recalls me the case with fold-left() function (not array:fold-left()) where we experienced x4 performance differences depending on structure of $zero parameter.
Updated by Michael Kay over 4 years ago
The bug was embarrassingly stupid. The implementation provides a standard call() interface
public Sequence<?> call(XPathContext context, Sequence[] arguments) throws XPathException {
and for the $zero argument it was using the standard coding pattern for singleton arguments:
Sequence zero = (Sequence)(arguments[1].head());
instead of
Sequence zero = arguments[1];
The real culprit was that all the QT3 test cases for this function used a singleton item as the value of $zero
.
Thanks for reminder about message 7888, but I'm afraid it hasn't been possible to find time to investigate this, given that there's no suggestion of a product bug, only a minor optimization opportunity.
Updated by O'Neil Delpratt about 4 years ago
- % Done changed from 0 to 100
- Fixed in Maintenance Release 10.2 added
Bug fix applied in the Saxon 10.2 maintenance release.
Updated by O'Neil Delpratt about 4 years ago
- Status changed from Resolved to Closed
- Fixed in Maintenance Release 9.9.1.8 added
Bug fix applied on the Saxon 9.9.1.8 maintenance release.
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