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=head1 NAME
XML::LibXML::Pattern - XML::LibXML::Pattern - interface to libxml2 XPath patterns
=head1 SYNOPSIS
use XML::LibXML;
my $pattern = new XML::LibXML::Pattern('/x:html/x:body//x:div', { 'x' => 'http://www.w3.org/1999/xhtml' });
# test a match on a XML::LibXML::Node $node
if ($pattern->matchesNode($node)) { ... }
# or on a XML::LibXML::Reader
if ($reader->matchesPattern($pattern)) { ... }
# or skip reading all nodes that do not match
print $reader->nodePath while $reader->nextPatternMatch($pattern);
$pattern = XML::LibXML::Pattern->new( pattern, { prefix => namespace_URI, ... } );
$bool = $pattern->matchesNode($node);
=head1 DESCRIPTION
This is a perl interface to libxml2's pattern matching support I<<<<<< http://xmlsoft.org/html/libxml-pattern.html >>>>>>. This feature requires recent versions of libxml2.
Patterns are a small subset of XPath language, which is limitted to
(disjunctions of) location paths involving the child and descendant axes in
abbreviated form as described by the extended BNF given below:
Selector ::= Path ( '|' Path )*
Path ::= ('.//' | '//' | '/' )? Step ( '/' Step )*
Step ::= '.' | NameTest
NameTest ::= QName | '*' | NCName ':' '*'
For readability, whitespace may be used in selector XPath expressions even
though not explicitly allowed by the grammar: whitespace may be freely added
within patterns before or after any token, where
token ::= '.' | '/' | '//' | '|' | NameTest
Note that no predicates or attribute tests are allowed.
Patterns are particularly useful for stream parsing provided via the C<<<<<< XML::LibXML::Reader >>>>>> interface.
=over 4
=item new()
$pattern = XML::LibXML::Pattern->new( pattern, { prefix => namespace_URI, ... } );
The constructor of a pattern takes a pattern expression (as described by the
BNF grammar above) and an optional HASH reference mapping prefixes to namespace
URIs. The method returns a compiled pattern object.
Note that if the document has a default namespace, it must still be given an
prefix in order to be matched (as demanded by the XPath 1.0 specification). For
example, to match an element C<<<<<< <a xmlns="http://foo.bar"</a> >>>>>>, one should use a pattern like this:
$pattern = XML::LibXML::Pattern->new( 'foo:a', { foo => 'http://foo.bar' });
=item matchesNode($node)
$bool = $pattern->matchesNode($node);
Given a XML::LibXML::Node object, returns a true value if the node is matched
by the compiled pattern expression.
=back
=head1 SEE ALSO
L<<<<<< XML::LibXML::Reader >>>>>> for other methods involving compiled patterns.
=head1 AUTHORS
Matt Sergeant,
Christian Glahn,
Petr Pajas
=head1 VERSION
1.70
=head1 COPYRIGHT
2001-2007, AxKit.com Ltd.
2002-2006, Christian Glahn.
2006-2009, Petr Pajas.
=cut
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