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<!DOCTYPE s1 SYSTEM "../../style/dtd/document.dtd">
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<s1 title="Extensions library">
<ul>
<li><link anchor="intro">Introduction</link></li>
<li><link anchor="xalanns">Xalan namespace</link></li>
<li><link anchor="redirect">Redirect</link></li>
<li><link anchor="nodeset">nodeset</link></li>
<li><link anchor="intersection">intersection</link></li>
<li><link anchor="difference">difference</link></li>
<li><link anchor="distinct">distinct</link></li>
<li><link anchor="hassamenodes">hasSameNodes</link></li>
<li><link anchor="sql">SQL extensions</link></li>
<li><link anchor="evaluate">evaluate</link></li>
<li><link anchor="tokenize">tokenize</link></li>
<li><link anchor="groupitem">group and item</link> <ref>(to be done)</ref></li>
<li><link anchor="type">type</link> <ref>(to be done)</ref></li>
<li><link anchor="todate">toDate</link> <ref>(to be done)</ref></li>
<li><link anchor="formatdate">formatDate</link> <ref>(to be done)</ref></li>
<li><link anchor="grep">grep</link> <ref>(to be done)</ref></li>
<li><link anchor="foreachtoken">forEachToken</link> <ref>(to be done)</ref></li>
<li>Examples: <link anchor="ex-redirect">Redirect</link>, <link anchor="ex-nodeset">nodeset</link>, <link anchor="ex-sql">SQL library</link></li>
</ul><anchor name="intro"/>
<s2 title= "Introduction">
<p>Extension elements and functions provide a powerful mechanism
for extending and simplifying what you can do with an XLST processor like
Xalan. With input and contributions from the XML open-source developer community, we are working on placing the most useful
extensions in an extensions library distributed with &xslt4j;. If you have ideas and/or contributions you would like to make, please email us at the <human-resource-ref idref="xalandev"/>.</p>
</s2><anchor name="xalanns"/>
<s2 title="Xalan namespace">
<p>Where it makes sense, we are placing the new Xalan extensions in the org.apache.xalan.lib.Extensions class and we have defined a namespace for this class:</p>
<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<code>http://xml.apache.org/xalan</code></p>
<p>If you are calling &xslt4j;-supplied extensions, we recommend that you define this namespace in your stylesheet element, and call the extension using the namespace prefix that you have associated with that namespace. That way, if we later reorganize how the &xslt4j;-supplied extensions are stored, you won't have to modify your stylesheet.</p>
<p>For an example that uses this namespace, see <link anchor="ex-nodeset">Example with the nodeset extension function</link>.</p>
</s2><anchor name="redirect"/>
<s2 title= "Redirect">
<p>A standard XSL transformation involves an XSL stylesheet, an XML source tree, and the transformation result tree. The transformation sends the entire result to a single <jump href="apidocs/org/apache/trax/Result.html">org.apache.trax.Result</jump> object.</p> 
<p>The Redirect extension 
(<jump href="apidocs/org/apache/xalan/xslt/extensions/Redirect.html">org.apache.xalan.xslt.extensions.Redirect</jump>) supplies three extension elements that you can use to redirect portions of your transformation output to multiple files: &lt;open&gt;, &lt;write&gt;, and &lt;close&gt;. If you use the &lt;write&gt; element alone, the extension opens a file, writes to it, and closes the file immediately. If you want explicit control over the opening and closing of files, use &lt;write&gt; in conjunction with the &lt;open&gt; and &lt;close&gt; elements.</p>
<p>Each of these elements includes a file attribute and/or a select attribute to designate the output file. The file attribute takes a string, so you can use it to directly specify the output file name. The select attribute takes an XPath expression, so you can use it to dynamically generate the output file name. If you include both attributes, the Redirect extension first evaluates the select attribute, and falls back to the file attribute if the select attribute expression does not return a valid file name.</p>
<anchor name="ex-redirect"/> 
<s3 title="Example with the Redirect extension">
<p>Suppose you are outputting the bulk of your result tree to one file, but you want to output the transformation of all &lt;foo&gt; elements and their children to another file. The following example illustrates the basic structure of the XML source:</p>
<source>&lt;?xml version="1.0"?&gt; 
&lt;doc&gt;
  &lt;foo file="foo.out"&gt;
    Testing Redirect extension:
      &lt;bar&gt;A foo subelement text node&lt;/bar&gt;
  &lt;/foo&gt;
  &lt;main&gt;
    Everything else
  &lt;/main&gt;  
&lt;/doc&gt;</source>
<p>This stylesheet redirects part of the output to a secondary file:</p>
<source>
&lt;xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    version="1.0"
    xmlns:lxslt="http://xml.apache.org/xslt"
    xmlns:redirect="org.apache.xalan.xslt.extensions.Redirect"
    extension-element-prefixes="redirect"&gt;

  &lt;xsl:template match="/"&gt;
    &lt;standard-out&gt;
      Standard output:
      &lt;xsl:apply-templates/&gt;
    &lt;/standard-out&gt;
  &lt;/xsl:template&gt;
  
  &lt;xsl:template match="main"&gt;
    &lt;main&gt;
      &lt;xsl:apply-templates/&gt;
    &lt;/main&gt;
  &lt;/xsl:template&gt;
  
  &lt;xsl:template match="/doc/foo"&gt;
    &lt;redirect:write select="@file"&gt;
      &lt;foo-out&gt;
        &lt;xsl:apply-templates/&gt;
      &lt;/foo-out&gt;
    &lt;/redirect:write&gt;
  &lt;/xsl:template&gt;
  
  &lt;xsl:template match="bar"&gt;
    &lt;foobar-out&gt;
      &lt;xsl:apply-templates/&gt;
    &lt;/foobar-out&gt;
  &lt;/xsl:template&gt;
  
&lt;/xsl:stylesheet&gt;</source>
<p>The standard output is:</p>
<source>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;standard-out&gt;
  Standard output:
  &lt;main&gt;
    Everything else.
  &lt;/main&gt;
&lt;standard-out&gt;</source>
<p>The output redirected to foo.out is:</p>
<source>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;foo-out&gt;
    Testing Redirect extension:
    &lt;foobar-out&gt;foo subelement text node&lt;/foobar-out&gt;
  &lt;/foo-out&gt;</source>
<p>For more information on using the Redirect extension to send output to multiple files, examine the <link idref="samples" anchor="ext1">SimpleRedirect</link> sample and see the <jump href="apidocs/org/apache/xalan/lib/Redirect.html">Redirect</jump> class Javadoc.</p>  
</s3></s2><anchor name="nodeset"/>
<s2 title= "nodeset">
<p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
<code>nodeset (result-tree-fragment)</code>  casts a result tree fragment into a node-set.</p>
<note>When you bind a variable to a template, rather than to the value generated by a select expression, the data type of the variable is result tree fragment. For more information, see <jump href="http://www.w3.org/TR/xslt#section-Result-Tree-Fragments">Result Tree Fragments</jump>.</note>
<anchor name="ex-nodeset"/>
<s3 title="Example with the nodeset extension function">
<p>The following stylesheet uses the nodeset extension function to cast a result tree fragment into a node-set that can then be navigated in standard XPath manner. It uses the http://xml.apache.org/xalan namespace to provide access to the nodeset() method in xml.apache.xalan.lib.Extensions.</p>
<source>&lt;?xml version="1.0"?&gt;
&lt;xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"
                xmlns:xalan="http://xml.apache.org/xalan"
                exclude-result-prefixes="xalan"&gt;
&lt;xsl:template match="/"&gt;
  &lt;out&gt;
	  &lt;xsl:variable name="rtf"&gt;
      &lt;docelem&gt;
        &lt;elem1&gt;
          &lt;elem1a&gt;ELEMENT1A&lt;/elem1a&gt;
          &lt;elem1b&gt;,ELEMENT1B&lt;/elem1b&gt;
        &lt;/elem1&gt;
        &lt;elem2&gt;
          &lt;elem2a&gt;ELEMENT2A&lt;/elem2a&gt;
        &lt;/elem2&gt;
      &lt;/docelem&gt;
    &lt;/xsl:variable&gt;     
      &lt;xsl:for-each select="xalan:nodeset($rtf)/docelem//*"&gt;
        &lt;xsl:value-of select="name(.)"/&gt;&lt;xsl:text&gt;,&lt;/xsl:text&gt;
      &lt;/xsl:for-each>
  &lt;/out>
&lt;/xsl:template> 
&lt;/xsl:stylesheet&gt;</source>
<p>The output of running this stylesheet (with any XML input source) is a comma-delimited list of the element names in the node-set<br/>
&nbsp;&nbsp;<code>&lt;out&gt;elem1,elem1a,elem1b,elem2,elem2a&lt;/out&gt;</code></p>
<note>For illustration purposes, the preceding stylesheet pays no attention to the structure and content of the XML input document. Instead, it processes the template (in the stylesheet) bound to the variable named rtf.</note>

</s3>
</s2><anchor name="intersection"/>
<s2 title="intersection">
<p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
<code>intersection (node-set1, node-set2)</code>  function returns a node-set with all nodes that are in ns1 and in ns2 .</p>
</s2><anchor name="difference"/>
<s2 title= "difference">
<p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
<code>difference(node-set1, node-set2)</code> returns a node-set with the nodes in node-set1 and not in node-set2.</p>
</s2><anchor name="distinct"/>
<s2 title= "distinct">
 <p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
 distinct (node-set) returns a node-set containing nodes with distinct string values. If more than one node in the node-set 
 contains the same text node value, distinct only returns the first of these nodes that it finds.</p>
</s2><anchor name="hassamenodes"/>
<s2 title= "hasSameNodes">
<p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
<code>hasSameNodes(node-set1, node-set2)</code> returns true if both node-set1 and node-set2 contain exactly the same set of nodes.</p>
</s2><anchor name="sql"/>
<s2 title= "SQL library">
<p><em>**Experimental**</em> Provides extension functions for connecting to a JDBC data source, executing a query,
and working incrementally through "streamable" result set.</p>
<p><em>The SQL extension use of a single row-set node to incrementally return a query result set is experimental. Keep in mind that you
can only access row elements one at a time moving forward through the result set. The use of XPath expressions in your stylesheet, for
example, that attempt to return nodes from the result set in any other manner may produce unpredictable results.</em></p>
<p><jump href="apidocs/org/apache/xalan/lib/sql/XConnection.html">org.apache.xalan.lib.sql.XConnection</jump> provides three extension functions that you can use in your stylesheet.</p>
    <ol>
      <li>new() -- Use one of the XConnection constructors to connect to a data source, and return an XConnection
       object.<br/><br/></li>
      <li>query() -- Use the XConnection object query() method to return a "streamable" result set in the form of a row-set
       node. Work your way through the row-set one row at a time. The same row element is used over and over again, so you can
       begin "transforming" the row-set before the entire result set has been returned.<br/><br/></li>
      <li>close() -- Use the XConnection object close() method to terminate the connection.</li>      
    </ol>
    <p>The query() extension function returns a Document node that contains (as needed) an array of column-header elements, 
    a single row element that is used repeatedly, and an array of col elements. Each column-header element (one per column in
    the row-set) contains an attribute (ColumnAttribute) for each of the column descriptors in the ResultSetMetaData object. 
    Each col element contains a text node with a textual representation of the value for that column in the current row.</p>
    <anchor name="ex-sql"/> 
    <s3 title="Example with SQL library">
    <p>This example displays the result set from a table in a sample InstantDB database. It is also
    available as a sample application; see 
    <link idref="samples" anchor="ext6">6-sqllib-instantdb</link>.</p>
<source>&lt;?xml version="1.0"?&gt;
&lt;xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0"
                xmlns:sql="org.apache.xalan.lib.sql.XConnection"
                extension-element-prefixes="sql"&gt;
  &lt;xsl:output method="html" indent="yes"/&gt;
  &lt;xsl:param name="query" select="'SELECT * FROM import1'"/&gt;
 
  &lt;xsl:template match="/"&gt;
    &lt;!-- 1. Make the connection --&gt;
    &lt;xsl:variable name="products"
                  select="sql:new('org.enhydra.instantdb.jdbc.idbDriver',
                                'jdbc:idb:.\instantdb\sample.prp')"/&gt;
    &lt;HTML&gt;
      &lt;HEAD&gt;
      &lt;/HEAD&gt;
      &lt;BODY&gt;
        &lt;TABLE border="1"&gt;
        &lt;!--2. Execute the query --&gt;
        &lt;xsl:variable name="table" select='sql:query($products, $query)'/&gt;
          &lt;TR&gt;
          &lt;!-- Get column-label attribute from each column-header--&gt;
          &lt;xsl:for-each select="$table/row-set/column-header"&gt;
            &lt;TH&gt;&lt;xsl:value-of select="@column-label"/&gt;&lt;/TH&gt;
          &lt;/xsl:for-each&gt;
          &lt;/TR&gt;
          &lt;xsl:apply-templates select="$table/row-set/row"/&gt;
          &lt;xsl:text&gt;&amp;#10;&lt;/xsl:text&gt;
        &lt;/TABLE&gt;
      &lt;/BODY&gt;
    &lt;/HTML&gt; 
    &lt;!-- 3. Close the connection --&gt;
    &lt;xsl:value-of select="sql:close($products)"/&gt;
  &lt;/xsl:template&gt;

  &lt;xsl:template match="row"&gt;
        &lt;TR&gt;
          &lt;xsl:apply-templates select="col"/&gt;
        &lt;/TR&gt;
  &lt;/xsl:template&gt;

  &lt;xsl:template match="col"&gt;
    &lt;TD&gt;
      &lt;!-- Here is the column data -->
      &lt;xsl:value-of select="text()"/>
    &lt;/TD>
  &lt;/xsl:template>

&lt;/xsl:stylesheet&gt;
</source>
</s3>
</s2><anchor name="evaluate"/>
<s2 title= "evaluate">
<p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
<code>evaluate (xpath-expression)</code> function returns the result of evaluating the xpath-expression in the current 
XPath expression context (automatically passed in by the extension mechanism).</p>
<p>Use the evaluation extension function when the value of the expression is not known until run time.</p>
</s2><anchor name="tokenize"/>
<s2 title="tokenize">
<p>Implemented in <jump href="apidocs/org/apache/xalan/lib/Extensions.html">org.apache.xalan.lib.Extensions</jump>,<br/>
<code>tokenize (tokenize-string, delimiters)</code><br/>
or<br/>
<code>tokenize (tokenize-string)</code> function returns a node-set containing one text node for each token in the tokenize-string.</p>
<p>The delimiters determine which characters are used to divide the tokenize-string into individual tokens. If you do not include
the delimiters argument, the function uses tab (&amp;#x09), linefeed (&amp;#x0A), return (&amp;#x0D), and space (&amp;#x20) as delimiters.
If tokenize-string is an empty string or contains only delimiters, the result is an empty node-set.</p>
</s2><anchor name="groupitem"/>
<s2 title= "group and item">
<p><em>To be done.</em> Provides efficient grouping of items with a common value.</p>
</s2><anchor name="type"/>
<s2 title= "type">
<p><em>To be done.</em> Returns a string that represents the Schema or DTD type.</p>
</s2><anchor name="todate"/>
<s2 title="to-date">
<p><em>To be done.</em> Takes a string as input, and returns a long value representing the date.</p>
</s2><anchor name="formatdate"/>
<s2 title="format-date">
<p><em>To be done.</em> Takes a date string, and formats it according to a specification.</p>
</s2><anchor name="grep"/>
<s2 title="grep">
<p><em>To be done.</em> Performs a grep function and returns the substring.</p>
</s2><anchor name="foreachtoken"/>
<s2 title="for-each-token">
<p><em>To be done.</em> Tokenizes a string, treats each token as a DOM Text node, and executes the
sub-template.</p>
</s2>
</s1>