How to extract information from a processing-instruction when transforming XML?

Question

I'm converting some XML files following a change to our DTD.

One of the changes involves changing what were processing-instructions into attributes on other elements - but I'm having trouble selecting specific information from instructions. I haven't been able to find much in how to use PIs - almost everything I find is about how to create them - but I did manage to find this: http://doccookbook.sourceforge.net/html/en/dbc.common.pi.html

For example - original XML:

<?Fm Condition FM8_SYSTEM_HIDEELEMENT Dark%20Grey NO_OVERRIDE hide AsIs?>
<?Fm Condition FM8_TRACK_CHANGES_ADDED Forest%20Green SINGLE_UNDERLINE show AsIs?>
<?Fm Condition FM8_TRACK_CHANGES_DELETED Red STRIKETHROUGH show AsIs?>

<products>
    <?Fm Condstart p-version?>
    <prod>
        <form>inj</form>
        <strength>10, 20, 50</strength>
    </prod>
    <?Fm Condend p-version?>

    <?Fm Condstart e-version?>
    <prod>
        <form>inj</form>
        <strength>10</strength>
        <packsize>0.4&nbsp;mL (syringe), 4</packsize>
    </prod>
    <prod>
        <form>inj</form>
        <strength>20</strength>
        <packsize>0.4&nbsp;mL (syringe), 4</packsize>
    </prod>
    <prod>
        <form>inj</form>
        <strength>50</strength>
        <packsize>0.4&nbsp;mL (syringe), 4</packsize>
    </prod>
    <?Fm Condend e-version?>
</products>

I tried this XSL template

<xsl:template match="processing-instruction()">
    <xsl:choose>
        <xsl:when test="'Condstart'">
            <xsl:text>ELEPHANTS</xsl:text>
        </xsl:when>

        <xsl:otherwise>
            <xsl:copy />
        </xsl:otherwise>
    </xsl:choose>
</xsl:template>

But it turns ALL of the processing instructions in the document to "ELEPHANTS" - not just the one I'm trying to select.

Answer 1

You want something like this:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

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

 <xsl:template match=
 "processing-instruction()[starts-with(.,'Condstart')]">
  <xsl:text>ELEPHANTS</xsl:text>
 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the provided (corrected for well-formedness) XML document:

<?Fm Condition FM8_SYSTEM_HIDEELEMENT Dark%20Grey NO_OVERRIDE hide AsIs?>
<?Fm Condition FM8_TRACK_CHANGES_ADDED Forest%20Green SINGLE_UNDERLINE show AsIs?>
<?Fm Condition FM8_TRACK_CHANGES_DELETED Red STRIKETHROUGH show AsIs?>
<products>
    <?Fm Condstart p-version?>
    <prod>
        <form>inj</form>
        <strength>10, 20, 50</strength>
    </prod>
    <?Fm Condend p-version?>
    <?Fm Condstart e-version?>
    <prod>
        <form>inj</form>
        <strength>10</strength>
        <packsize>0.4&#xA0;mL (syringe), 4</packsize>
    </prod>
    <prod>
        <form>inj</form>
        <strength>20</strength>
        <packsize>0.4&#xA0;mL (syringe), 4</packsize>
    </prod>
    <prod>
        <form>inj</form>
        <strength>50</strength>
        <packsize>0.4&#xA0;mL (syringe), 4</packsize>
    </prod>
    <?Fm Condend e-version?>
</products>

the wanted, correct result is produced:

<?Fm Condition FM8_SYSTEM_HIDEELEMENT Dark%20Grey NO_OVERRIDE hide AsIs?>
<?Fm Condition FM8_TRACK_CHANGES_ADDED Forest%20Green SINGLE_UNDERLINE show AsIs?>
<?Fm Condition FM8_TRACK_CHANGES_DELETED Red STRIKETHROUGH show AsIs?>
<products>
    ELEPHANTS
    <prod>
        <form>inj</form>
        <strength>10, 20, 50</strength>
    </prod>
    <?Fm Condend p-version?>
    ELEPHANTS
    <prod>
        <form>inj</form>
        <strength>10</strength>
        <packsize>0.4 mL (syringe), 4</packsize>
    </prod>
    <prod>
        <form>inj</form>
        <strength>20</strength>
        <packsize>0.4 mL (syringe), 4</packsize>
    </prod>
    <prod>
        <form>inj</form>
        <strength>50</strength>
        <packsize>0.4 mL (syringe), 4</packsize>
    </prod>
    <?Fm Condend e-version?>
</products>