~/t/ftemp $ cat roger1.xml
<?xml version="1.0" encoding="UTF-8"?>
<Root>
    <D1>
        <D2/>
        <F1/>
    </D1>
    <D2>
        <F2/>
    </D2>
</Root>
~/t/ftemp $ cat roger2.xml
<?xml version="1.0" encoding="UTF-8"?>
<Root>
    <D1>
        <D2/>
        <F1/>
    </D1>
    <D2>
        <F2/>
        <F1/>
    </D2>
</Root>
~/t/ftemp $ xslt2 roger1.xml roger.xsl
true
true
true
~/t/ftemp $ xslt2 roger2.xml roger.xsl
false
false
false
~/t/ftemp $ cat roger.xsl
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  exclude-result-prefixes="xs"
  version="2.0">

<xsl:template match="/">
  <xsl:value-of select="
    count(/Root/*/*)=count(distinct-values(/Root/*/*/name(.)))"/>
  <xsl:text>&#xa;</xsl:text>
  <xsl:value-of select="
    every $elem in /Root/*/* satisfies
          not($elem/following::*[not(*)]/node-name(.)=node-name($elem))"/>
  <xsl:text>&#xa;</xsl:text>
  <xsl:value-of select="
    not( some $elem in /Root/*/* satisfies
              $elem/following::*[not(*)]/node-name(.)=node-name($elem))"/>
  <xsl:text>&#xa;</xsl:text>
</xsl:template>

</xsl:stylesheet>
~/t/ftemp $

Hi Folks,

I am modeling a file system. Below is a sample instance. D1 means Directory 1, F1 means File 1, etc. The instance says this: the content of directory 1 is directory 2 and file 1. The content of directory 2 is file 2. Stated another way, directory 2 and file 1 are contained in directory 1, and file 2 is contained in directory 2.

<Root>
    <D1>
        <D2/>
        <F1/>
    </D1>
    <D2>
        <F2/>
    </D2>
</Root>

I want an XPath 2.0 expression which returns true if each object has one parent. An "object" is a directory or a file. In the example above each object has one parent, so the XPath should return true. Below is an illegal file system because F1 has two parents: D1 and D2.

<Root>
    <D1>
        <D2/>
        <F1/>
    </D1>
    <D2>
        <F2/>
        <F1/>
    </D2>
</Root>

The XPath should return false.

This XPath is almost correct:

for $i in /Root/* return for $j in $i/* return not(name($j) = $i/following-sibling::*/*/name())

I say it is "almost" correct because it returns multiple Booleans, not a single Boolean result.

Two Questions:

1. What is the correct XPath expression?
2. Is there a different way to model in XML a file system that would enable a simple XPath expression?

/Roger

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