# NAME XML::XSS - XML stylesheet system # VERSION version 0.3.5 # SYNOPSIS ```perl use XML::XSS; my $xss = XML::XSS->new; $xss->set( pod => { pre => "=pod\n", post => "=cut\n", } ); $xss->set( section => { pre => \&pre_section } ); sub pre_section { my ( $self, $node, $args ) = @_; return "=head1 " . $node->findvalue( '@title' ) . "\n\n"; } print $xss->render( <<'END_XML' );
XML::XSS - a XML stylesheet system
...
END_XML ``` # DESCRIPTION Caution: this is alpha-quality software. Here be enough dragons to send Beowulf packing. Caveat maximus emptor. `XML::XSS` is a XML stylesheet system loosely similar to CSS and XSLT. A `XML::XSS` object is made up of rendering rules that dictate how the different nodes of an XML document are to be rendered, and can be applied against one or many XML documents. `XML::XSS` is a rewrite of [XML::XPathScript](https://metacpan.org/pod/XML::XPathScript), which was initially part of the [AxKit](https://metacpan.org/pod/AxKit) framework. ## The XML Document `XML::XSS` uses [XML::LibXML](https://metacpan.org/pod/XML::LibXML) under the hood as its XML DOM API. Documents can be passed as strings, in which case the creation of the XML::LibXML object will be done behind the curtain ``` $xss->render( 'yadah' ); ``` or the [XML::LibXML](https://metacpan.org/pod/XML::LibXML) object can be passed directly ```perl my $doc = XML::LibXML->load_xml( location => 'foo.xml' ); $xss->render( $doc ); ``` ## Stylesheet Rules `XML::XSS` has 5 different kinds of rules that reflect the different kinds of nodes that a XML document can have (as per [XML::LibXML](https://metacpan.org/pod/XML::LibXML)): [XML::XSS::Document](https://metacpan.org/pod/XML::XSS::Document), [XML::XSS::Text](https://metacpan.org/pod/XML::XSS::Text), [XML::XSS::Comment](https://metacpan.org/pod/XML::XSS::Comment), [XML::XSS::ProcessingInstruction](https://metacpan.org/pod/XML::XSS::ProcessingInstruction) and [XML::XSS::Element](https://metacpan.org/pod/XML::XSS::Element). Whereas there are can many `XML::LibXML::Element` rules, there is only one instance of each of the first 4 rules per stylesheet. In addition of the regular `XML::LibXML::Element` rules, a special _catch-all_ `XML::LibXML::Element` also exists that will be applied to any document element not explicitly matched by one of the element rules. ## Rules Style Attributes Each rule has a set of style attributes that control how the matching document node is transformed. The different types of rule ([XML::XSS::Document](https://metacpan.org/pod/XML::XSS::Document), [XML::XSS::Element](https://metacpan.org/pod/XML::XSS::Element), [XML::XSS::Text](https://metacpan.org/pod/XML::XSS::Text), [XML::XSS::Comment](https://metacpan.org/pod/XML::XSS::Comment) and [XML::XSS::ProcessingInstruction](https://metacpan.org/pod/XML::XSS::ProcessingInstruction)) have each a different set of style attributes, which are described in their relative manpages. Unless specified otherwise, a style attribute can be assigned a scalar value or a reference to a sub. In the second case, the sub will be evaluated in the context of the processed node and its return value will be used as the style attribute value. Upon execution, the sub references will be passed three parameters: the invoking rule, the `XML::LibXML` node it is rendering and the arguments ref given to `render()`. ```perl $css->set( 'foo' => { pre => '[[[', post => sub { my ( $self, $node, $args ) = @_; return $node->findvalue( '@bar' ); } } ); ``` ## Modifying Rules While Rendering Rules attributes changed while rendering only apply to the current element. ```perl $xss->set( 'section' => { process => sub { my ( $self, $node ) = @_; $self->stash->{section_nbr}++; if ( $self->stash->{section_nbr} == 5 ) { # only applies to the one section $self->set_pre( '>>> this is the fifth section <<<' ); } return 1; } } ); ``` If you want to change the global rule, you have to access the rule from the stylesheet, like so ```perl $xss->set( 'section' => { process => sub { my ( $self, $node ) = @_; $self->stash->{section_nbr}++; if ( $self->stash->{section_nbr} == 6 ) { $self->stylesheet->element('section')->set_pre( '>>> this is after the fifth section <<<' ); } return 1; } } ); ``` # ATTRIBUTES ## document The document rule. Note that this matches against the `XML::LibXML::Document` node, not the root element node of the document. ### document() Attribute getter. ## text The text rule. ### text() Attribute getter. ### set\_text( ... ) Shortcut for ``` $xss->text->set( ... ); ``` ### clear\_text() Shortcut for ``` $xss->text->clear; ``` ## comment The comment rule. ### comment() Attribute getter. ### set\_comment( ... ) Shortcut for ``` $xss->comment->set( ... ) ``` ## elements The collection of user-defined element rules. ### element( $name ) Returns the [XML::XSS::Element](https://metacpan.org/pod/XML::XSS::Element) node associated to the tag `$name`. If the element didn't already exist, it is automatically created. ```perl my $elt = $xss->element( 'foo' ); # element for $elt->set( pre => '[foo]' ); ``` ## catchall\_element The catch-all element rule, which is applied to all the element nodes that aren't explicitly matched. ```perl # change all tags to except for $xss->set( 'foo' => { showtag => 1 } ); $xss->set( '*' => { rename => 'unknown' } ); ``` ### catchall\_element() The attribute getter. ## stash The stylesheet has a stash (an hashref) that is accessible to all the rules during the rendering of a document, and can be used to pass information back and forth. ```perl $xss->set( section => { intro => \§ion_title, } ); # turns
... # into 1. blah sub section_title { my ( $self, $node, $args ) = @_; my $section_nbr = $self->stash->{section_nbr}++; return $section_nbr . ". " . $node->findvalue( '@title' ); } ``` By default, the stash is cleared when rendering a document. To change this behavior, see ["use\_clean\_stash" in XML::XSS::Document](https://metacpan.org/pod/XML::XSS::Document#use_clean_stash). ### stash() The attribute getter. ### clear\_stash() Clear the stash. # OVERLOADING ## Concatenation (.) The concatenation operator is overloaded to behave as an alias for `get()`. ```perl my $chapter = $xss.'chapter'; # just like $xss->get('chapter') $chapter->set_pre( '
' ); $chapter->set_post( '
' ); ``` Gets really powerful when used in concert with the overloading of the rules and style attributes: ``` # equivalent as example above $xss.'chapter'.'pre' *= '
'; $xss.'chapter'.'post' *= '
'; ``` # METHODS ## set( $element\_1 => \\%attrs, $element\_2 => \\%attrs\_2, ... ) Sets attributes for a rendering node. The `$name` can be an XML element name, or one of the special keywords `#document`, `#text`, `#comment`, `#pi` or `*` (for the _catch-all_ element), which will resolve to the corresponding rendering object. ```perl $xss->set( 'foo' => { rename => 'bar' } ); # same as $xss->element('foo')->set( rename => 'bar' ); $xss->set( '#text' => { filter => { uc shift } } ); # same as $xss->text->set( filter => { uc shift } ); ``` Note that subsequent calls to `set()` are additive. I.e.: ```perl $xss->set( foo => { pre => 'X' } ); $xss->set( foo => { post => 'Y' } ); # pre is still set to 'X' ``` If you want to delete an attribute, passes it `undef` as its value. ## render( $xml, \\%args ) Returns the output produced by the application of the stylesheet to the xml document. The xml can be passed as a string, or as a `XML::LibXML` object. Several `XML::LibXML` objects can also be passed, in which case the return value will be the concatenation of their transformations. ```perl my $sections = $xss->render( $doc->findnodes( 'section' ) ); ``` The `%args` is optional, and will defaults to an empty hash if not provided. The reference to `%args` is also passed to the recursive calls to `render()` for the children of the processed node, which allows for another way for parent/children nodes to pass information in addition to the `stash`. ```perl # count the descendents of all nodes $xss->set( '*' => { process => sub { my ( $self, $node, $attrs ) = @_; $attrs->{children}++; return 1; }, content => sub { my ( $self, $node, $attrs ) = @_; my %c_attrs; my $c_ref = \%c_attrs; my $output = $self->render( $node->childNodes, $c_ref ); $attrs->{children} += $c_ref->{children}; $self->{post} = "\n>>> node has " . ($c_ref->{children}||0) . " descendents\n"; return $output; }, } ); ``` # AUTHOR Yanick Champoux [![endorse](http://api.coderwall.com/yanick/endorsecount.png)](http://coderwall.com/yanick) # COPYRIGHT AND LICENSE This software is copyright (c) 2017, 2013, 2011, 2010 by Yanick Champoux. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.