XSLT 1.0 - extract node-set and pass as param

Question

I am given this XML and have to render quite a bit from it and most is working fine, but I am stomped trying to extract the node-set of color whos key matches the key of the bar element and the attribute is a hardcoded string ('data' in this case). The node-set is to be passed as parameter to a template and each color line must only appear once:

<report>
    <settings>
        <colors>
            <color key="1-1" name="frame" value="..." ... />
            <color key="1-1" name="data" value="..." ... />
            <color key="2-1" name="frame" value="..." ... />
            <color key="2-1" name="data" value="..." ... />
            <color key="3-1" name="frame" value="..." ... />
            <color key="3-1" name="data" value="..." ... />
        </colors>
        <comp>
             <cont>
                  <bar key="1-1" .../>
                  <bar key="1-1" .../>
                  <bar key="2-1" .../>
             </cont>
        <comp>
        <!-- possibly more <comp/cont/bar> below that may not be mixed with the above -->
     </settings>
</report>

In my XSLT file I have this (extract):

<xsl:key name="barnode" match="bar" use="@key"/>
<xsl:key name="colorlookup" match="/report/settings/colors/color" use="@key"/>

<!-- this runs at the `cont` element level, i.e. `bar` can be accessed without prefix -->

<!-- set $x to the node-list of bars with unique @key attribute -->
<xsl:call-template name="renderit">
    <xsl:with-param name="colors">
        <!-- 'bars' contains node-set of 'bar' elements with @key being unique -->
        <xsl:variable name="bars" select="bar[generate-id() = generate-id(key('barnode', @key)[1])]"/>
        <xsl:for-each select="$bars">
            <xsl:value-of select="key('colorlookup', @key)[@name='data']"/>
        </xsl:for-each>
    </xsl:with-param>
</xsl:call-template>

The problem is, that this does not pass a node-set, but a tree-fragment. Is it possible to make a select that does the same as above, but returns a node-set?

Edit:

Expected node-set:

<color key="1-1" name="data" value="..." ... />
<color key="2-1" name="data" value="..." ... />

I am not sure if the presented XSLT will even generate this result tree fragment as I don't know how to print it (for debug purposes).

Answer 1

Try

<xsl:with-param name="colors" select="key('colorlookup', bar[generate-id() = generate-id(key('barnode', @key)[1])]/@key)[@name = 'data']"/>