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<refentry xml:id="function.xslt-process" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>xslt_process</refname>
  <refpurpose>Perform an XSLT transformation</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>xslt_process</methodname>
   <methodparam><type>resource</type><parameter>xh</parameter></methodparam>
   <methodparam><type>string</type><parameter>xmlcontainer</parameter></methodparam>
   <methodparam><type>string</type><parameter>xslcontainer</parameter></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>resultcontainer</parameter></methodparam>
   <methodparam choice="opt"><type>array</type><parameter>arguments</parameter></methodparam>
   <methodparam choice="opt"><type>array</type><parameter>parameters</parameter></methodparam>
  </methodsynopsis>
  <para>
   The <function>xslt_process</function> function is the crux of the XSLT
   extension.  It allows you to perform an XSLT transformation using
   almost any type of input source - the containers.  This is accomplished
   through the use of argument buffers -- a concept taken from the Sablotron
   XSLT processor (currently the only XSLT processor this extension supports).
   The input containers default to a filename 'containing' the document to be
   processed. 
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>xh</parameter></term>
     <listitem>
      <para>
       The XSLT processor link identifier, created with
       <function>xslt_create</function>.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>xmlcontainer</parameter></term>
     <listitem>
      <para>
       Path to XML file or placeholder for the XML argument.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>xslcontainer</parameter></term>
     <listitem>
      <para>
       Path to XSL file or placeholder for the XML argument.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>resultcontainer</parameter></term>
     <listitem>
      <para>
       The result container defaults to a filename for the transformed
       document. If the result container is not specified - i.e. &null;
       - than the result is returned.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>arguments</parameter></term>
     <listitem>
      <para>
       Instead of files as the XML and XSLT arguments to the <function>xslt_process</function>
       function, you can specify &quot;argument place holders&quot; which are then substituted by values
       given in the <parameter>arguments</parameter> array.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>parameters</parameter></term>
     <listitem>
      <para>
       An array for any top-level parameters that will be passed to the XSLT
       document.  These parameters can then be accessed within your XSL files
       using the &lt;xsl:param name=&quot;parameter_name&quot;&gt;
       instruction. The parameters must be UTF-8 encoded and their values will be
       interpreted as strings by the <productname>Sablotron</productname> processor.
       In other words - you cannot pass node-sets as parameters to the XSLT document.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
  <para>
   Containers can also be set via the <parameter>arguments</parameter>
   array (see below).
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success; If the result container is not specified - i.e.
   &null; - than the result is returned.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>4.0.6</entry>
       <entry>
        This function no longer takes XML strings in
        <parameter>xmlcontainer</parameter> or 
        <parameter>xslcontainer</parameter>. Passing a string containing XML
        to either of these parameters will result in a segmentation fault in
        Sablotron versions up to and including version 0.95.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   The simplest type of transformation with the
   <function>xslt_process</function> function is the transformation of an
   XML file with an XSLT file, placing the result in a third file containing
   the new XML (or HTML) document.  Doing this with sablotron is really
   quite easy...
  </para>
  <example>
   <title>Using the <function>xslt_process</function> to transform an XML
   file and a XSL file to a new XML file</title>
   <programlisting role="php">
<![CDATA[
<?php

// Allocate a new XSLT processor
$xh = xslt_create();

// Process the document
if (xslt_process($xh, 'sample.xml', 'sample.xsl', 'result.xml')) {
    echo "SUCCESS, sample.xml was transformed by sample.xsl into result.xml";
    echo ", result.xml has the following contents\n<br />\n";
    echo "<pre>\n";
    readfile('result.xml');
    echo "</pre>\n";
} else {
    echo "Sorry, sample.xml could not be transformed by sample.xsl into";
    echo "  result.xml the reason is that " . xslt_error($xh) . " and the ";
    echo "error code is " . xslt_errno($xh);
}

xslt_free($xh);

?>
]]>
   </programlisting>
  </example>
  <para>
   While this functionality is great, many times, especially in a web environment, you want to
   be able to print out your results directly.  Therefore, if you omit the third argument to
   the <function>xslt_process</function> function (or provide a NULL value for the argument), it
   will automatically return the value of the XSLT transformation, instead of writing it to a
   file...
  </para>
  <para>
   <example>
   <title>Using the <function>xslt_process</function> to transform an XML file and a XSL file
   to a variable containing the resulting XML data</title>
   <programlisting role="php">
<![CDATA[
<?php

// Allocate a new XSLT processor
$xh = xslt_create();

// Process the document, returning the result into the $result variable
$result = xslt_process($xh, 'sample.xml', 'sample.xsl');
if ($result) {
    echo "SUCCESS, sample.xml was transformed by sample.xsl into the \$result";
    echo " variable, the \$result variable has the following contents\n<br />\n";
    echo "<pre>\n";
    echo $result;
    echo "</pre>\n";
} else {
    echo "Sorry, sample.xml could not be transformed by sample.xsl into";
    echo "  the \$result variable the reason is that " . xslt_error($xh);
    echo " and the error code is " . xslt_errno($xh);
}

xslt_free($xh);

?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   The above two cases are the two simplest cases there are when it comes to XSLT transformation
   and I'd dare say that they are the most common cases, however, sometimes you get your XML and
   XSLT code from external sources, such as a database or a socket.  In these cases you'll have
   the XML and/or XSLT data in a variable -- and in production applications the overhead of dumping
   these to file may be too much.  This is where XSLT's &quot;argument&quot; syntax, comes to the
   rescue.  Instead of files as the XML and XSLT arguments to the <function>xslt_process</function>
   function, you can specify &quot;argument place holders&quot; which are then substituted by values
   given in the arguments array (5th parameter to the <function>xslt_process</function> function).
   The following is an example of processing XML and XSLT into a result variable without the use
   of files at all.
  </para>
  <para>
   <example>
   <title>Using the <function>xslt_process</function> to transform a variable containing XML data
   and a variable containing XSL data into a variable containing the resulting XML data</title>
   <programlisting role="php">
<![CDATA[
<?php
// $xml and $xsl contain the XML and XSL data

$arguments = array(
     '/_xml' => $xml,
     '/_xsl' => $xsl
);

// Allocate a new XSLT processor
$xh = xslt_create();

// Process the document
$result = xslt_process($xh, 'arg:/_xml', 'arg:/_xsl', NULL, $arguments);
if ($result) {
    echo "SUCCESS, sample.xml was transformed by sample.xsl into the \$result";
    echo " variable, the \$result variable has the following contents\n<br />\n";
    echo "<pre>\n";
    echo $result;
    echo "</pre>\n";
} else {
    echo "Sorry, sample.xml could not be transformed by sample.xsl into";
    echo "  the \$result variable the reason is that " . xslt_error($xh);
    echo " and the error code is " . xslt_errno($xh);
}
xslt_free($xh);
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example>
    <title>Passing PHP variables to XSL files</title>
    <programlisting role="php">
<![CDATA[
<?php

// XML string
$xml = '<?xml version="1.0"?>
<para>
 change me
</para>';

// XSL string
$xsl = '
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="html" encoding="ISO-8859-1" indent="no"
 omit-xml-declaration="yes"  media-type="text/html"/>
 <xsl:param name="myvar"/>
 <xsl:param name="mynode"/>
 <xsl:template match="/">
My PHP variable : <xsl:value-of select="$myvar"/><br />
My node set : <xsl:value-of select="$mynode"/>
 </xsl:template>
</xsl:stylesheet>';


$xh = xslt_create();

// the second parameter will be interpreted as a string
$parameters = array (
  'myvar' => 'test',
  'mynode' => '<foo>bar</foo>'
);

$arguments = array (
  '/_xml' => $xml,
  '/_xsl' => $xsl
);

echo xslt_process($xh, 'arg:/_xml', 'arg:/_xsl', NULL, $arguments, $parameters);

?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
My PHP variable : test<br>
My node set : &lt;foo&gt;bar&lt;/foo&gt;
]]>
    </screen>
   </example>
  </para>
 </refsect1>
 
 <refsect1 role="notes">
  &reftitle.notes;
  &note.xslt.windows;
 </refsect1>

</refentry>

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