[xsl] xsl:for - Only for existing nodes, how?

["Liron" <magilam@xxxxxxxxxxxxxxxx>]

Hello,

I'm trying to figure out the best way to transform a node-set only if it 
includes certain nodes, Lets assume I have the following xml structure:

<tree>
  <controls>
     <control>
        <dummy><data>some data</data></dummy>
        <item1><data>some data</data></item1>
        <item2><data>some data</data></item2>
     </control>
     <control>
        <dummy><data>some data</data></dummy>
        <item1><data>some data</data></item1>
        <item2><data>some data</data></item2>
     </control>
  </controls>
</tree>

I want to select the values of item1's data and item2's data so I'm doing 
this:
<xsl:for-each select="/tree/controls/control">
  <xsl:value-of select="item1/data"/>
  <xsl:value-of select="item2/data"/>
</xsl:for-each>

This is all fine but my problem begins when there're more "control" nodes 
with no item1 or item2 children. So if there's one more "control" child (for 
the example above) which is empty then the for loop will itterate 3 times 
while I need it to itterate only 2 times for real values. I thought about 
doing something like:
<xsl:for-each select="/tree/controls/control/item1">
   <xsl:value-of select="data"/>
   <xsl:value-of select="../item2/data"/>
</xsl:for-each>

But I'm hoping that there's a more celver way to do what I want.

Thank you very much