Re: Re: limiting preceding axis by ancestor

Joerg Heinicke <joerg dot heinicke at gmx dot de> wrote:

> The [1] is implicit and not needed, because generate-id() on a 
> nodeset returns the id of the first element in this nodeset. I wrote 
> it for maybe better understanding.
> 
> <xsl:if test=". = preceding::bar[generate-id(ancestor::foo[1]) = 
> generate-id(current()/ancestor::foo[1])]">

This is one case where the established belief that 

generate-id(someXPathExpression) = generate-id(someXPathExpression[1])

is *not* true.

This is clearly not so, because "ancestor" is a reverse axis.

generate-id(ancestor::foo[1]) 

will be applied on the nearest ancesstor (the last in document order)

while

generate-id(ancestor::foo)

will be applied on the outermost ancestor (the first in document
order).


Here's a small example illustrating this (I'm using the "preceding"
axis here, as I have a suitable xml file at hand):

The source xml is:

testxp17.xml:
------------
<groups>
    <group>
        <tables>
            <table index="1" />
            <table index="2" />
        </tables>
        <views>
            <view index="3" />
            <view index="4" />
        </views>
    </group>
    <group>
        <tables>
            <table index="1" />
        </tables>
        <views>
            <view index="1" />
        </views>
    </group>
</groups>


The transformation is:

<xsl:stylesheet version="1.0" 
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="text"/>
  <xsl:template match="/">
    <xsl:variable name="vlastView" select="(//view)[last()]"/>
    <xsl:variable name="vID1" 
         select="generate-id($vlastView/preceding::tables[1])"/>
    <xsl:variable name="vID2" 
         select="generate-id($vlastView/preceding::tables)"/>


    <xsl:value-of 
    select="concat('generate-id($vlastView/preceding::tables[1]) = '
                                 , $vID1
                                 , '&#xA; '
                                 )"/>
    <xsl:value-of 
    select="concat('generate-id($vlastView/preceding::tables) = '
                                 , $vID2
                                 , '&#xA;' 
                                 )"/>
                                 
    <xsl:value-of select="concat('(gID1 = gID2) = ', $vID1 = $vID2)"/>
  </xsl:template>
</xsl:stylesheet> 


The results are:

1. with Saxon:

generate-id($vlastView/preceding::tables[1]) = d0e22
 generate-id($vlastView/preceding::tables) = d0e5
(gID1 = gID2) = false


2. with MSXML4:

generate-id($vlastView/preceding::tables[1]) = IDANMS0B
 generate-id($vlastView/preceding::tables) = IDACMS0B
(gID1 = gID2) = false

Cheers,
Dimitre Novatchev.





__________________________________________________
Do You Yahoo!?
Yahoo! Health - your guide to health and wellness
http://health.yahoo.com

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list