Processing Textile Text with XSLT

07 Oct 2004 | Tags xslt programming snippets tips textile

Textile provides a simple way of writing human-friendly text that can easily be translated to XHTML. HTML tags are simplified into a set of phrase and block modifiers; even tables and attributes can be created.

I was looking at the PHP code for this and wondering if I could create an XSL file that could translate similar text into XHTML. I created some XML to contain my text:

<textile>
<![CDATA[
*Hello*

This should be in *bold*.

Hello
]]>
</textile>

And then used the following recursive algorithm to process it in XSLT:

 <xsl:template name="replace-string">
    <xsl:param name="text"/>
    <xsl:param name="from"/>
    <xsl:param name="to_close"/>
    <xsl:param name="to_open"/>
    <xsl:param name="tagon"/>

    <xsl:choose>
        <xsl:when test="contains($text, $from)">
            <xsl:variable name="before" select="substring-before($text, $from)"/>
            <xsl:variable name="after" select="substring-after($text, $from)"/>
            <xsl:value-of select="$before"/>
            <xsl:choose>
                <xsl:when test="$tagon=0">
                    <xsl:variable name="prefix" select="concat($before, $to_open)"/>
                    <xsl:value-of select="$to_open"/>
                </xsl:when>
                <xsl:otherwise>
                    <xsl:variable name="prefix" select="concat($before, $to_close)"/>
                    <xsl:value-of select="$to_close"/>
                </xsl:otherwise>
            </xsl:choose>

            <xsl:call-template name="replace-string">
                <xsl:with-param name="text" select="$after"/>
                <xsl:with-param name="from" select="$from"/>
                <xsl:with-param name="to_close" select="$to_close"/>
                <xsl:with-param name="to_open" select="$to_open"/>
                <xsl:with-param name="tagon" select="1-$tagon"/>
            </xsl:call-template>
        </xsl:when>
        <xsl:otherwise>
            <xsl:value-of select="$text"/>
        </xsl:otherwise>
    </xsl:choose>
 </xsl:template>

This code was based on this example at the ASPN XSLT Cookbook.

Although I managed to create an example of using this text, it’s obvious that the PHP code is far more understandable than the XSLT code. It’s well-known that XSLT isn’t as friendly as most programming languages for string processing, and I think this example illustrates this. Despite it being possible to process text this way, it’s currently much more efficient to rely on PHP, java, python, perl and so on.