XML::LibXML::Pattern(3User Contributed Perl DocumentaXML::LibXML::Pattern(3pm)NAMEXML::LibXML::Pattern - 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);
$pattern = XML::LibXML::Pattern->new( pattern, { prefix => namespace_URI, ... } );
$bool = $pattern->matchesNode($node);
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 for other methods involving compiled patterns.
AUTHORS
Matt Sergeant, Christian Glahn, Petr Pajas
VERSION
1.70
COPYRIGHT
2001-2007, AxKit.com Ltd.
2002-2006, Christian Glahn.
2006-2009, Petr Pajas.
perl v5.10.0 2009-10-07 XML::LibXML::Pattern(3pm)
