Is '//' and 'descendant-or-self' not the same

[Martin Beck]

Hello,

with Saxon 8.0b the following query's results different values. Why?

<xsl:value-of select="/root/descendant-or-self::test[5]/@title" />

<xsl:value-of select="/root//test[5]/@title" />

The input document:

<?xml version="1.0" encoding="iso-8859-1"?>

<root>

    <test title="test1" />
   
    <test title="test2" />
   
    <container>
        <test title="test3" />
    </container>
   
    <container>
        <test title="test4" />
    </container>
   
    <test title="test5" />
   
   
    <test title="test6" />
   
   
    <test title="test7" />

</root>

The Stylesheet:

<?xml version="1.0" encoding="iso-8859-1"?>

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:output method="text" encoding="iso-8859-1" />   

    <xsl:template match="/">
   
        <xsl:for-each select="/root//test">
            <xsl:value-of select="position()" />
            <xsl:text> </xsl:text>
            <xsl:value-of select="@title" /><xsl:text>&#x0A;</xsl:text>
            </xsl:for-each>
   
        <xsl:text>&#x0A;</xsl:text>
        <xsl:text>&#x0A;</xsl:text>
       
        <xsl:text>Why is the result of this two XPATH-Querys different? Is '//' not equal 'descendant-or-self::' ?</xsl:text>
        <xsl:text>&#x0A;</xsl:text>
        <xsl:value-of select="/root/descendant-or-self::test[5]/@title" />
        <xsl:text>&#x0A;</xsl:text>
        <xsl:value-of select="/root//test[5]/@title" />
   
    </xsl:template>
   
   

</xsl:stylesheet>

Thanks for help.

Martin

[Michael Kay]

This is a basic XPath coding question and doesn't really belong on the Saxon list.

//a[5] means /descendant-or-self::node/a[5], and selects every a element that is the fifth child of its parent.

/descendant-or-self::a[5] selects the fifth a element that is a descendant (or self) of the root node.

Michael Kay

[Stefan_E]

Sorry for reviving such an old thread: Whilst I can see the logic in above
example, I still get confused on my example... hmm (using Saxon 9.4.0.3
through Oxygen)

My document looks something like this (graphml file to be processed with yed):

<root>
<node isLeaf="Y"/>
<node isLeaf="N">
<graph>
<node isLeaf="Y"/>
<node/>
</graph>
</node>
<node isLeaf="N">
<graph/>
</node>
<node isLeaf="N">
<graph>
<node isLeaf="Y"/>
</graph>
</node>
</root>

I don't want remove the node which doesn't have a leaf node <node isLeave="Y">
So, I'm using an xsl template as follows:

<xsl:template match="node">
<xsl:if test="descendant-or-self::node">
<node>
<xsl:apply-templates select="@*|node()"/>
</node>
</xsl:if>
</xsl:template>

which works.

But using

<xsl:if test="//node">

copies everything ...How does the predicate get matched?

Thanks for help,
Stefan

[Stefan_E]

"I don't want remove" --> I want remove ... :-)

[Markus Abt]

No, "//" is not the same as "descendant-or-self".
Neither is "descendant-or-self::node" the same as "//node".

"//" is the same as "/descendant-or-self::node()/".

Therefore, "//node" is the same as "/descendant-or-self::node()/child::node"
Which is in two aspects different from "descendant-or-self::node":
1. the former starts at the root node "/", the latter doesn't.
2. Note the additional step on the child axis in the former.

Regards,
Markus