XML::LibXML::Pattern - interface to libxml2 XPath patterns

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);

Description
This is a perl interface to libxml2's pattern matching support 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 XML::LibXML::Reader interface.
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 <a xmlns="http://foo.bar"</a>, one should use a pattern like this:

$pattern = XML::LibXML::Pattern->new( 'foo:a', { foo => 'http://foo.bar' });

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.

SEE ALSO
XML::LibXML::Reader - interface to libxml2 pull parser for other methods involving compiled patterns.