XML::LibXML::Pattern

Section: User Contributed Perl Documentation (3pm)
Updated: 2014-04-12
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NAME

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

SYNOPSIS

  use XML::LibXML;
  my $pattern = XML::LibXML::Pattern->new('/x:html/x:body//x:div', { 'x' => 'http://www.w3.org/1999/xhtml' });
  # test a match on an XML::LibXML::Node $node

  if ($pattern->matchesNode($node)) { ... }

  # or on an 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 limited 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 an 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

2.0116  

COPYRIGHT

2001-2007, AxKit.com Ltd.

2002-2006, Christian Glahn.

2006-2009, Petr Pajas.  

LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


 

Index

NAME
SYNOPSIS
DESCRIPTION
SEE ALSO
AUTHORS
VERSION
COPYRIGHT
LICENSE