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¶

2.0018

COPYRIGHT¶

2001-2007, AxKit.com Ltd.

2002-2006, Christian Glahn.

2006-2009, Petr Pajas.