What is the default select of XSLT apply-templates?

Question

The identity template looks like this:

<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()" />
    </xsl:copy>
</xsl:template>

Does <xsl:apply-templates select="@*|node()" /> select more than <xsl:apply-templates />, or could the identity template have been like this?

<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates />
    </xsl:copy>
</xsl:template>

What exactly is selected when I do the following?

<xsl:apply-templates />

score 20 · Accepted Answer · answered Oct 03 '12 at 12:00

20

Does <xsl:apply-templates select="@*|node()" /> select more than <xsl:apply-templates />, or could the identity template have been like this?

<xsl:apply-templates/>

is equivalent to:

<xsl:apply-templates select="node()"/>

and this is a shorter former of:

<xsl:apply-templates select="child::node()"/>

and this is a equivalent to:

<xsl:apply-templates select="* | text() | comment() | processing-instruction()"/>

As we see from the last instruction, the xsl:apply-templates instruction you are asking about, doesn't select any attributes, therefore it cannot be used as a shorthand for:

<xsl:apply-templates select="@*|node()"/>

answered Oct 03 '12 at 12:00

Dimitre Novatchev

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@OP: P.S. this is defined at http://www.w3.org/TR/xslt#section-Applying-Template-Rules: "In the absence of a select attribute, the xsl:apply-templates instruction processes all of the children of the current node, including text nodes. ..." Note that attribute nodes are *not* considered children of their parent element. – LarsH Nov 20 '13 at 11:20
@LarsH, Yes, but sometimes readers find quoting the Specs to be "intimidating" :) – Dimitre Novatchev Nov 20 '13 at 14:25
Yeah, if I had to choose between only quoting the Spec and only explaining what it means, I would choose your answer (unless I thought the implications of the spec were very easy to understand on this point). However in conjunction with a helpful explanation, I think pointing users to the primary material helps them "learn how to fish." The OP here seems to be an accomplished programmer, who shouldn't be afraid of the spec. :-) – LarsH Nov 20 '13 at 15:44

score 5 · Answer 2 · answered Oct 03 '12 at 11:37

5

The default select for <xsl:apply-templates/> is just "node()", it doesn't include attributes.

answered Oct 03 '12 at 11:37

Ian Roberts

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Ah, then makes perfect sense then :) – Svish Oct 03 '12 at 11:39

score 2 · Answer 3 · answered Dec 06 '12 at 18:15

The default selection of apply-templates is node(), which is shorthand for child::node(). This XPath expressions is evaluated as follows:

First, all nodes from the "child" axis are taken. This are all the direct children of the current element, i.e. other elements, text, and comments, but not the attributes.
Then this node set is filtered with the node test "node()". In this case, no elements are filtered because that test matches everything.

So with <xsl:apply-templates />, templates for the child elements are applied but not for the attributes. In case of the copy template this would mean that the attributes are not copied.

What is the default select of XSLT apply-templates?

3 Answers3

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