RE: [xsl] grouping sequence question

[TSchutzerWeissmann@xxxxxxxxxxxxxxxx]

Hello Paul

[...]
> what if I can't evaluate by string->
> not(start-with(@ref, 'GRP')), but need to judge from
> whether the element can apply another templates.
> because there are lots different groups, and naming by
> different people, etc.
> such as , I add a GRP xs:element in the schema which
> is tailor for this 'GRP2'
> <xs:element name="GRP2">
> 	<xs:complexType>
> 		<xs:sequence>
> 			<xs:element ref="GRP-for-mail"
> maxOccurs="unbounded"/>
> 		</xs:sequence>
> 	</xs:complexType>
> </xs:element>

Nested groups are a bit more complicated, so I'm going to stick with
defining group elements as having a ref attribute that begins with "GRP". 

Let's say you want to output this:
Group starts
---> apply templates to any child group (ie, recurse)
Group ends
Group members.

Since a "child group" isn't going to be a direct child node, you can either
set up an XPath that can cope with the hierarchy of xs:complexType,
xs:sequence, whatever, or you could use a key -

<xsl:key name="childGRPs" match="xs:element[starts-with(@ref, 'GRP')]"
  use="generate-id(ancestor::xs:element[starts-with(@ref, 'GRP')][1])"/>

The [1] makes sure that you only recurse one level at a time, giving you
child groups but no grandchild groups.

The real complication though, is the first key. This is because you don't
want to associate elements with a preceding group that's nested deeper than
they are, so you need to alter the preceding axis and only consider
preceding-siblings or ancestors of preceding-siblings...

<xsl:key name="byGRP"  match="xs:element[not(starts-with(@ref, 'GRP'))]"
  use="generate-id(ancestor-or-self::*/preceding-sibling::xs:element
       [starts-with(@ref, 'GRP')][1])"/>
 
Then you just need to set the recursive template going by sending the first
level of groups to it:




<xsl:template match="/xs:schema/xs:element">
  <!-- for each group -->
  <xsl:for-each select="//xs:element[starts-with(@ref, 'GRP')]">
    <xsl:variable name="me" select="generate-id()"/>

    <xsl:value-of select="@ref"/> begins:
    <xsl:apply-templates select="key('childGRPs',$me)"/>   <!-- recurse over
any children -->
    <xsl:value-of select="@ref"/> ends.


    <xsl:for-each select="key('byGRP',$me)">
      <xsl:value-of select="@ref"/> Starts
    </xsl:for-each>

    <xsl:for-each select="key('byGRP',$me)">
      <xsl:value-of select="@ref"/> Ends
    </xsl:for-each>

  </xsl:for-each>
</xsl:template>

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