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Re: isXPath1 / isXPath2 -- not(/..)

• From: "Hermann Stamm-Wilbrandt" <STAMMW@de.ibm.com>
• To: Michael Kay <mike@saxonica.com>
• Date: Sat, 19 Dec 2015 21:54:17 +0100

Thank you Michael, your "0">"" is the minimal "isXPath2" expression:

$ java -jar ~/Desktop/saxon6-5-5/saxon.jar dummy.xml xpv.xsl
true
true
false
$
$ java -jar ~/Downloads/saxon9608/saxon9he.jar -xsl:xpv.xsl -s:dummy.xml
true
false
true
$
$ cat xpv.xsl
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>
<xsl:output omit-xml-declaration="yes" />

<xsl:template match="/">
<xsl:value-of select="not(/..)"/><xsl:text>&#10;</xsl:text>
<xsl:value-of select="(4=5)=/.."/><xsl:text>&#10;</xsl:text>
<xsl:value-of select='"0">""'/><xsl:text>&#10;</xsl:text>
</xsl:template>

</xsl:stylesheet>
$


Mit besten Gruessen / Best wishes,

Hermann Stamm-Wilbrandt
Compiler Level 3 support & Fixpack team lead
IBM DataPower Gateways (⬚ᵈᵃᵗᵃ / ⣏⠆⡮⡆⢹⠁⡮⡆⡯⠂⢎⠆⡧⡇⣟⡃⡿⡃)
https://www.ibm.com/developerworks/mydeveloperworks/blogs/HermannSW/
https://twitter.com/HermannSW/ https://stamm-wilbrandt.de/GraphvizFiddle/
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Michael Kay ---19.12.2015 20:00:05---> On 19 Dec 2015, at 14:12, Hermann Stamm-Wilbrandt <STAMMW@de.ibm.com> wrote: >

From: Michael Kay <mike@s...>
To: Hermann Stamm-Wilbrandt/Germany/IBM@IBMDE
Cc: xml-dev@l...
Date: 19.12.2015 20:00
Subject: Re: isXPath1 / isXPath2 -- not(/..)

On 19 Dec 2015, at 14:12, Hermann Stamm-Wilbrandt <STAMMW@de.ibm.com> wrote:


More than a year ago Jonathan Robie tweeted on this nice XPath expression:
false()=/..

The expression is true for XPath 1.0 and false for XPath 2.0.
Therefore the expression can be named "isXPath1".

1. The rules for comparing a node-set to a boolean have changed. In XPath 1.0, an expression such as $node-set = true() was evaluated by converting the node-set to a boolean and then performing a boolean comparison: so this expression would return true if $node-set was non-empty. In XPath 2.0, this expression is handled in the same way as other comparisons between a sequence and a singleton: it is true if $node-set contains at least one node whose value, after atomization and conversion to a boolean using the casting rules, is true.
This means that if $node-set is empty, the result under XPath 2.0 will be false regardless of the value of the boolean operand, and regardless of which operator is used. If $node-set is non-empty, then in most cases the comparison with a boolean is likely to fail, giving a dynamic error. But if a node has the value "0", "1", "true", or "false", evaluation of the expression may succeed.

not(/..)

This expression is true for XPath 2.0 and false for XPath 1.0.

• References:
  • isXPath1 / isXPath2 -- not(/..)
    • From: "Hermann Stamm-Wilbrandt" <STAMMW@de.ibm.com>
  • Re: isXPath1 / isXPath2 -- not(/..)
    • From: Michael Kay <mike@saxonica.com>