Question

How can I transform an XML document with XSLT such, that I read the input, apply a transformation (e.g. trim the leading and trailing whitespaces) to all elements in the document and return the XML document with its complete structure as it was?
(see also How can I trim space in XSLT without replacing repating whitespaces by single ones? for the trim-problem)

I started with the following code for copying all elements:

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

which works fine. Now I wanted to apply the transformation by adding some lines:

<xsl:template match="@* | node()">
    <xsl:copy>

      <xsl:apply-templates select="@* | node()">
        <xsl:call-template name="string-trim">
          <xsl:with-param name="string" select="@* | node()" />
        </xsl:call-template>
      </xsl:apply-templates>

    </xsl:copy>
</xsl:template>

But it seems that it is not allowed to add a “call-template”-Tag inside a “apply-templates”-Tag.

How can I copy the complete structure from the source-document into the target-document while applying the transformation to each element?

Answer 1

You can have separate templates for text() and @*…

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output indent="yes"/>
    <xsl:strip-space elements="*"/>

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

    <xsl:template match="text()">
        <xsl:call-template name="string-trim">
            <xsl:with-param name="string" select="." />
        </xsl:call-template>                
    </xsl:template>

    <xsl:template match="@*">
        <xsl:attribute name="{name()}">
            <xsl:call-template name="string-trim">
                <xsl:with-param name="string" select="." />
            </xsl:call-template>        
        </xsl:attribute>
    </xsl:template>

    <xsl:template name="string-trim">
        <xsl:param name="string"/>
        ?????
    </xsl:template>

</xsl:stylesheet>

Don’t forget to replace the template named “string-trim” with yours.