phpman > perldoc > XML::LibXSLT(3pm)

NAME
    XML::LibXSLT - Interface to the GNOME libxslt library

SYNOPSIS
      use XML::LibXSLT;
      use XML::LibXML;

      my $xslt = XML::LibXSLT->new();

      my $source = XML::LibXML->load_xml(location => 'foo.xml');
      my $style_doc = XML::LibXML->load_xml(location=>'bar.xsl', no_cdata=>1);

      my $stylesheet = $xslt->parse_stylesheet($style_doc);

      my $results = $stylesheet->transform($source);

      print $stylesheet->output_as_bytes($results);

DESCRIPTION
    This module is an interface to the GNOME project's libxslt. This is an extremely good XSLT
    engine, highly compliant and also very fast. I have tests showing this to be more than twice as
    fast as Sablotron.

OPTIONS
    XML::LibXSLT has some global options. Note that these are probably not thread or even fork safe
    - so only set them once per process. Each one of these options can be called either as class
    methods, or as instance methods. However either way you call them, it still sets global options.

    Each of the option methods returns its previous value, and can be called without a parameter to
    retrieve the current value.

    max_depth
          XML::LibXSLT->max_depth(1000);

        This option sets the maximum recursion depth for a stylesheet. See the very end of section
        5.4 of the XSLT specification for more details on recursion and detecting it. If your
        stylesheet or XML file requires seriously deep recursion, this is the way to set it. Default
        value is 250.

    max_vars
          XML::LibXSLT->max_vars(100_000);

        This option sets the maximum number of variables for a stylesheet. If your stylesheet or XML
        file requires many variables, this is the way to increase their limit. Default value is
        system-specific and may vary.

    debug_callback
          XML::LibXSLT->debug_callback($subref);

        Sets a callback to be used for debug messages. If you don't set this, debug messages will be
        ignored.

    register_function
          XML::LibXSLT->register_function($uri, $name, $subref);
          $stylesheet->register_function($uri, $name, $subref);

        Registers an XSLT extension function mapped to the given URI. For example:

          XML::LibXSLT->register_function("urn:foo", "bar",
            sub { scalar localtime });

        Will register a "bar" function in the "urn:foo" namespace (which you have to define in your
        XSLT using "xmlns:...") that will return the current date and time as a string:

          <xsl:stylesheet version="1.0"
            xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
            xmlns:foo="urn:foo">
          <xsl:template match="/">
            The time is: <xsl:value-of select="foo:bar()"/>
          </xsl:template>
          </xsl:stylesheet>

        Parameters can be in whatever format you like. If you pass in a nodelist it will be a
        XML::LibXML::NodeList object in your perl code, but ordinary values (strings, numbers and
        booleans) will be ordinary perl scalars. If you wish them to be "XML::LibXML::Literal",
        "XML::LibXML::Number" and "XML::LibXML::Number" values respectively then set the variable
        $XML::LibXSLT::USE_LIBXML_DATA_TYPES to a true value. Return values can be a nodelist or a
        plain value - the code will just do the right thing. But only a single return value is
        supported (a list is not converted to a nodelist).

    register_element
                $stylesheet->register_element($uri, $name, $subref)

        Registers an XSLT extension element $name mapped to the given URI. For example:

          $stylesheet->register_element("urn:foo", "hello", sub {
                  my $name = $_[2]->getAttribute( "name" );
                  return XML::LibXML::Text->new( "Hello, $name!" );
          });

        Will register a "hello" element in the "urn:foo" namespace that returns a "Hello, X!" text
        node. You must define this namespace in your XSLT and include its prefix in the
        "extension-element-prefixes" list:

          <xsl:stylesheet version="1.0"
            xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
            xmlns:foo="urn:foo"
                extension-element-prefixes="foo">
          <xsl:template match="/">
            <foo:hello name="bob"/>
          </xsl:template>
          </xsl:stylesheet>

        The callback is passed the input document node as $_[1] and the stylesheet node as $_[2].
        $_[0] is reserved for future use.

API
    The following methods are available on the new XML::LibXSLT object:

    parse_stylesheet($stylesheet_doc)
        $stylesheet_doc here is an XML::LibXML::Document object (see XML::LibXML) representing an
        XSLT file. This method will return a XML::LibXSLT::Stylesheet object, or undef on failure.
        If the XSLT is invalid, an exception will be thrown, so wrap the call to parse_stylesheet in
        an eval{} block to trap this.

        IMPORTANT: $stylesheet_doc should not contain CDATA sections, otherwise libxslt may
        misbehave. The best way to assure this is to load the stylesheet with no_cdata flag, e.g.

          my $stylesheet_doc = XML::LibXML->load_xml(location=>"some.xsl", no_cdata=>1);

    parse_stylesheet_file($filename)
        Exactly the same as the above, but parses the given filename directly.

Input Callbacks
    To define XML::LibXSLT or XML::LibXSLT::Stylesheet specific input callbacks, reuse the
    XML::LibXML input callback API as described in XML::LibXML::InputCallback(3).

    input_callbacks($icb)
        Enable the callbacks in $icb only for this XML::LibXSLT object. $icb should be a
        "XML::LibXML::InputCallback" object. This will call "init_callbacks" and "cleanup_callbacks"
        automatically during parsing or transformation.

Security Callbacks
    To create security preferences for the transformation see XML::LibXSLT::Security. Once the
    security preferences have been defined you can apply them to an XML::LibXSLT or
    XML::LibXSLT::Stylesheet instance using the "security_callbacks()" method.

XML::LibXSLT::Stylesheet
    The main API is on the stylesheet, though it is fairly minimal.

    One of the main advantages of XML::LibXSLT is that you have a generic stylesheet object which
    you call the transform() method passing in a document to transform. This allows you to have
    multiple transformations happen with one stylesheet without requiring a reparse.

    transform(doc, %params)
          my $results = $stylesheet->transform($doc, foo => "'bar'");
          print $stylesheet->output_as_bytes($results);

        Transforms the passed in XML::LibXML::Document object, and returns a new
        XML::LibXML::Document. Extra hash entries are used as parameters. Be sure to keep in mind
        the caveat with regard to quotes explained in the section on "Parameters" below.

    transform_file(filename, %params)
          my $results = $stylesheet->transform_file($filename, bar => "'baz'");

        Note the string parameter caveat, detailed in the section on "Parameters" below.

    output_as_bytes(result)
        Returns a scalar that is the XSLT rendering of the XML::LibXML::Document object using the
        desired output format (specified in the xsl:output tag in the stylesheet). Note that you can
        also call $result->toString, but that will *always* output the document in XML format which
        may not be what you asked for in the xsl:output tag. The scalar is a byte string encoded in
        the output encoding specified in the stylesheet.

    output_as_chars(result)
        Like "output_as_bytes(result)", but always return the output as (UTF-8 encoded) string of
        characters.

    output_string(result)
        DEPRECATED: This method is something between "output_as_bytes(result)" and
        "output_as_bytes(result)": The scalar returned by this function appears to Perl as
        characters (UTF8 flag is on) if the output encoding specified in the XSLT stylesheet was
        UTF-8 and as bytes if no output encoding was specified or if the output encoding was other
        than UTF-8. Since the behavior of this function depends on the particular stylesheet, it is
        deprecated in favor of "output_as_bytes(result)" and "output_as_chars(result)".

    output_fh(result, fh)
        Outputs the result to the filehandle given in $fh.

    output_file(result, filename)
        Outputs the result to the file named in $filename.

    output_encoding()
        Returns the output encoding of the results. Defaults to "UTF-8".

    output_method()
        Returns the value of the "method" attribute from "xsl:output" (usually "xml", "html" or
        "text"). If this attribute is unspecified, the default value is initially "xml". If the
        transform method is used to produce an HTML document, as per the XSLT spec
        <http://www.w3.org/TR/xslt#output>, the default value will change to "html". To override
        this behavior completely, supply an "xsl:output" element in the stylesheet source document.

    media_type()
        Returns the value of the "media-type" attribute from "xsl:output". If this attribute is
        unspecified, the default media type is initially "text/xml". This default changes to
        "text/html" under the same conditions as output_method.

    input_callbacks($icb)
        Enable the callbacks in $icb only for this stylesheet. $icb should be a
        "XML::LibXML::InputCallback" object. This will call "init_callbacks" and "cleanup_callbacks"
        automatically during transformation.

Parameters
    LibXSLT expects parameters in XPath format. That is, if you wish to pass a string to the XSLT
    engine, you actually have to pass it as a quoted string:

      $stylesheet->transform($doc, param => "'string'");

    Note the quotes within quotes there!

    Obviously this isn't much fun, so you can make it easy on yourself:

      $stylesheet->transform($doc, XML::LibXSLT::xpath_to_string(
            param => "string"
            ));

    The utility function does the right thing with respect to strings in XPath, including when you
    have quotes already embedded within your string.

XML::LibXSLT::Security
    Provides an interface to the libxslt security framework by allowing callbacks to be defined that
    can restrict access to various resources (files or URLs) during a transformation.

    The libxslt security framework allows callbacks to be defined for certain actions that a
    stylesheet may attempt during a transformation. It may be desirable to restrict some of these
    actions (for example, writing a new file using exsl:document). The actions that may be
    restricted are:

    read_file
        Called when the stylesheet attempts to open a local file (ie: when using the document()
        function).

    write_file
        Called when an attempt is made to write a local file (ie: when using the exsl:document
        element).

    create_dir
        Called when a directory needs to be created in order to write a file.

        NOTE: By default, create_dir is not allowed. To enable it a callback must be registered.

    read_net
        Called when the stylesheet attempts to read from the network.

    write_net
        Called when the stylesheet attempts to write to the network.

  Using XML::LibXSLT::Security
    The interface for this module is similar to XML::LibXML::InputCallback. After creating a new
    instance you may register callbacks for each of the security options listed above. Then you
    apply the security preferences to the XML::LibXSLT or XML::LibXSLT::Stylesheet object using
    "security_callbacks()".

      my $security = XML::LibXSLT::Security->new();
      $security->register_callback( read_file  => $read_cb );
      $security->register_callback( write_file => $write_cb );
      $security->register_callback( create_dir => $create_cb );
      $security->register_callback( read_net   => $read_net_cb );
      $security->register_callback( write_net  => $write_net_cb );

      $xslt->security_callbacks( $security );
       -OR-
      $stylesheet->security_callbacks( $security );

    The registered callback functions are called when access to a resource is requested. If the
    access should be allowed the callback should return 1, if not it should return 0. The callback
    functions should accept the following arguments:

    $tctxt
        This is the transform context (XML::LibXSLT::TransformContext). You can use this to get the
        current XML::LibXSLT::Stylesheet object by calling "stylesheet()".

          my $stylesheet = $tctxt->stylesheet();

        The stylesheet object can then be used to share contextual information between different
        calls to the security callbacks.

    $value
        This is the name of the resource (file or URI) that has been requested.

    If a particular option (except for "create_dir") doesn't have a registered callback, then the
    stylesheet will have full access for that action.

  Interface
    new()
        Creates a new XML::LibXSLT::Security object.

    register_callback( $option, $callback )
        Registers a callback function for the given security option (listed above).

    unregister_callback( $option )
        Removes the callback for the given option. This has the effect of allowing all access for
        the given option (except for "create_dir").

BENCHMARK
    Included in the distribution is a simple benchmark script, which has two drivers - one for
    LibXSLT and one for Sablotron. The benchmark requires the testcases files from the XSLTMark
    distribution which you can find at http://www.datapower.com/XSLTMark/

    Put the testcases directory in the directory created by this distribution, and then run:

      perl benchmark.pl -h

    to get a list of options.

    The benchmark requires XML::XPath at the moment, but I hope to factor that out of the equation
    fairly soon. It also requires Time::HiRes, which I could be persuaded to factor out, replacing
    it with Benchmark.pm, but I haven't done so yet.

    I would love to get drivers for XML::XSLT and XML::Transformiix, if you would like to contribute
    them. Also if you get this running on Win32, I'd love to get a driver for MSXSLT via OLE, to see
    what we can do against those Redmond boys!

LIBRARY VERSIONS
    For debugging purposes, XML::LibXSLT provides version information about the libxslt C library
    (but do not confuse it with the version number of XML::LibXSLT module itself, i.e. with
    $XML::LibXSLT::VERSION). XML::LibXSLT issues a warning if the runtime version of the library is
    less then the compile-time version.

    XML::LibXSLT::LIBXSLT_VERSION()
        Returns version number of libxslt library which was used to compile XML::LibXSLT as an
        integer. For example, for libxslt-1.1.18, it will return 10118.

    XML::LibXSLT::LIBXSLT_DOTTED_VERSION()
        Returns version number of libxslt library which was used to compile XML::LibXSLT as a
        string, e.g. "1.1.18".

    XML::LibXSLT::LIBXSLT_RUNTIME_VERSION()
        Returns version number of libxslt library to which XML::LibXSLT is linked at runtime (either
        dynamically or statically). For example, for example, for libxslt.so.1.1.18, it will return
        10118.

    XML::LibXSLT::HAVE_EXLT()
        Returns 1 if the module was compiled with libexslt, 0 otherwise.

LICENSE
    This is free software, you may use it and distribute it under the same terms as Perl itself.

    Copyright 2001-2009, AxKit.com Ltd.

AUTHOR
    Matt Sergeant, matt AT sergeant.org

    Security callbacks implementation contributed by Shane Corgatelli.

MAINTAINER
    Petr Pajas , pajas AT matfyz.org

BUGS
    Please report bugs via

      http://rt.cpan.org/NoAuth/Bugs.html?Dist=XML-LibXSLT

SEE ALSO
    XML::LibXML