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[xsl] Looping through a tree and retaining parent values

2009-04-01 09:58:36
Hi Everyone,

I'm puzzling over a transformation that I thought would be simple but
which becomes progressively more complex as I try to wrap my mind
around it.

Here is a series of menuItem nodes, which are nested in menuItems
nodes. Each menuItem node has a label attribute.

<menuConfig>
        <menu id="A">
                <menuItems>
                        <menuItem label="1">
                                <menuItems>
                                        <menuItem label="a"/>
                                                <menuItems>
                                                        <menuItem label="1a">
                                                                <menuItems>
                                                                        
<menuItem label="1a.a"/>
                                                                        
<menuItem label="1a.b"/>
                                                                </menuItems>
                                                        </menuItem>
                                                </menuItems>
                                        <menuItem label="b">
                                        </menuItem>
                                </menuItems>
                        </menuItem>
                        <menuItem label="2">
                                <menuItems>
                                        <menuItem label="c"/>
                                        <menuItem label="d">
                                                <menuItems>
                                                        <menuItem label="2d">
                                                                <menuItems>
                                                                        
<menuItem label="2d.d"/>
                                                                        
<menuItem label="2d.e"/>
                                                                        
<menuItem label="2d.f"/>
                                                                </menuItems>
                                                        </menuItem>

                                                </menuItems>
                                        </menuItem>
                                        <menuItem label="e">
                                                <menuItems>
                                                        <menuItem label="2e">
                                                                <menuItems>
                                                                        
<menuItem label="2e.g"/>
                                                                </menuItems>
                                                        </menuItem>
                                                </menuItems>
                                        </menuItem>
                                </menuItems>
                        </menuItem>
                </menuItems>
        </menu>
</menuConfig>

What I'm trying to do is create a set of p nodes which nest a series
of uicontrol nodes, one uicontrol node for each level of menuItem in
the original XML document. In other words, for each menuItem in the
original XML, there should be a uicontrol element. The first uicontrol
node in the series contains the @label value for the parent menuItem
node. The next uiconcontrol node in the series contains the @label
value for the first child menuItem node, and so on.

The p node should have an id attribute whose value is the @label value
of the last child node in each tree.

Here is an example:

<body>
        <p id="1">
                <uicontrol>1</uicontrol>
        </p>
        <p id="a">
                <uicontrol>1</uicontrol> &gt;
                <uicontrol>a</uicontrol></p>
        <p id="1a">
                <uicontrol>1</uicontrol> &gt;
                <uicontrol>a</uicontrol> &gt;
                <uicontrol>1a</uicontrol>
        </p>
        <p id="1.1a">
                <uicontrol>1</uicontrol> &gt;
                <uicontrol>a</uicontrol> &gt;
                <uicontrol>1a</uicontrol> &gt;
                <uicontrol>1a.a</uicontrol>
        </p>
        <p id="1.1b">
                <uicontrol>1</uicontrol> &gt;
                <uicontrol>a</uicontrol> &gt;
                <uicontrol>1a</uicontrol> &gt;
                <uicontrol>1b.b</uicontrol>
        </p>
        <p id="b">
                <uicontrol>1</uicontrol> &gt;
                <uicontrol>b</uicontrol>
        </p>
        <p id="2">
                <uicontrol>2</uicontrol>
        <p id="c">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>c</uicontrol>
        </p>
        <p id="d">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>d</uicontrol>
        </p>
        <p id="2d">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>d</uicontrol> &gt;
                <uicontrol>2d</uicontrol>
        </p>
        <p id="2d.d">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>d</uicontrol> &gt;
                <uicontrol>2d</uicontrol> &gt;
                <uicontrol>2d.d</uicontrol>
        </p>
        <p id="2d.e">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>d</uicontrol> &gt;
                <uicontrol>2d</uicontrol> &gt;
                <uicontrol>2d.e</uicontrol>
        </p>
        <p id="e">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>e</uicontrol>
        </p>
        <p id="2e">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>e</uicontrol> &gt;
                <uicontrol>2e</uicontrol></p>
        <p id="2e.g">
                <uicontrol>2</uicontrol> &gt;
                <uicontrol>e</uicontrol> &gt;
                <uicontrol>2e</uicontrol> &gt;
                <uicontrol>2e.g</uicontrol>
        </p>
</body>

So far, I've come up with a stylesheet that produces a single p node
for every parent menuItem. It's a start. I've thought about trying to
use variables to retain the menuItem/@label values at each level in
the tree; but, reading about variables, I'm not sure this is possible.
Likewise, I've thought about defining each loop in a separate template
and then calling each template from the "master" template. But then,
I'm not sure how I'd retrieve the final menuItem/@label value for the
p/@id value.

And I must not understand the last() function correctly. The p/@id
values inserted by the stylesheet are "1a" and "2e.g," and not the
@label value for the last menuItem in each tree.

<xsl:template match="/">
                <xsl:for-each select="//menu">
                        <body>
                                <xsl:for-each select="menuItems">
                                        <xsl:for-each select="menuItem">
                                                <p>
                                                        <xsl:attribute 
name="id">

<xsl:value-of select="descendant::menuItem[last()]/@label"/>
                                                        </xsl:attribute>
                                                        <uicontrol>
                                                                <xsl:value-of 
select="@label"/>
                                                        </uicontrol> &gt;
                                                        <xsl:for-each 
select="descendant::menuItem[2]">
                                                                <uicontrol>
                                                                        
<xsl:value-of select="@label"/>
                                                                </uicontrol> 
&gt;
                                                                        
<xsl:for-each select="descendant::menuItem[3]">
                                                                        
<uicontrol>
                                                                                
<xsl:value-of select="@label"/>
                                                                        
</uicontrol> &gt;
                                                                                
        <xsl:for-each select="descendant::menuItem[4]">
                                                                                
<uicontrol>
                                                                                
        <xsl:value-of select="@label"/>
                                                                                
</uicontrol> &gt;
                                                                                
                <xsl:for-each select="descendant::menuItem[5]">
                                                                                
        <uicontrol>
                                                                                
                <xsl:value-of select="@label"/>
                                                                                
        </uicontrol> &gt;
                                                                                
                </xsl:for-each>
                                                                        
</xsl:for-each>
                                                                </xsl:for-each>
                                                        </xsl:for-each>
                                                </p>
                                        </xsl:for-each>
                                </xsl:for-each>
                        </body>
                </xsl:for-each>
        </xsl:template>

I'd appreciate any help you could offer.

Thanks,
Mark
-- 

Mark Peters
Senior Technical Writer
Saba Software

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