Copying Entire Subtrees

Often a fragment of a foreign grammar is to be encapsulated in another. In the following example, the "logo" element contains arbitrary well-formed HTML. When transforming this data to HTML, the contents of the "logo" element should be copied directly to the output.

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="portfolio2.xsl"?>
<portfolio xmlns:dt="urn:schemas-microsoft-com:datatypes">
  <stock exchange="nyse">
    <name>zacx corp</name>
    <symbol>ZCXM</symbol>
    <price dt:dt="number">28.875</price>
    <logo>
      <A href="http://www.zacx-corp.com">
        <IMG src="zacxcorp.gif"/>
      </A>
    </logo>
  </stock>
  <stock exchange="nasdaq">
    <name>zaffymat inc</name>
    <symbol>ZFFX</symbol>
    <price dt:dt="number">92.250</price>
    <logo><P STYLE="font:italic 14pt 'Arial Black'">zaffymat</P></logo>
  </stock>
</portfolio>

The identity transformation introduced in Filtering XML can be used locally to copy the logo subtree from the source document to the result tree. Defining a limited scope for the template will prevent the identity transform from applying outside the subtree. The scope is defined by placing the identity transform template within the <xsl:apply-templates> element, indicating that the elements selected thereby are to be processed with this specific template. For more details on scoping, see Scoping Templates.

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl">
  <xsl:template match="/">
    <HTML>
      <BODY>
        <xsl:for-each select="portfolio/stock">
          <DIV STYLE="font-size:smaller">Symbol: <xsl:value-of select="symbol"/>,
            Company: <xsl:value-of select="name"/>,
            Price: $<xsl:value-of select="price"/>
          </DIV>
          <DIV>
            <!-- select the children of the logo element -->
            <xsl:apply-templates select="logo/*">
              <!-- recursively apply this template to them -->
              <xsl:template>
                <xsl:copy>
                  <xsl:apply-templates select="@* | * | comment() | pi() | text()"/>
                </xsl:copy>
              </xsl:template>
            </xsl:apply-templates>
          </DIV>
          <HR/>
        </xsl:for-each>
      </BODY>
    </HTML>
  </xsl:template>
</xsl:stylesheet>

The element children of the "logo" element are processed by the identity transformation, copying this entire subtree to the output, so the embedded HTML appears in the output.

Try it! This style sheet is used in the Portfolio Sample (Embedded HTML).

Download this sample.