XML::Li...Pattern(3)

💖 XML::LibXML::Pattern — the manual page, but make it make sense 💖

okay bestie, so this is a section 3 page from the User Contributed Perl Documentation — it's the whole vibe on XML::LibXML::Pattern, which is basically your backstage pass to libxml2's XPath pattern matching. no cap. 🦋

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✨ NAME ✨

XML::LibXML::Pattern — the interface to libxml2 XPath patterns. that's it, that's the name, periodt. 💅

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🌸 SYNOPSIS 🌸

here's the whole thing in action, copy it exactly bestie:

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);

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🧚 DESCRIPTION 🧚

so this is a perl interface to libxml2's pattern matching support, which lives over at http://xmlsoft.org/html/libxml-pattern.html. lowkey important: this feature requires recent versions of libxml2. so if yours is ancient, that's a vibe check it's gonna fail. 😭

Patterns are a small subset of the XPath language. like, a tiny subset. it's limited to (disjunctions of) location paths involving the child and descendant axes in abbreviated form, exactly as described by this extended BNF:

Selector ::=     Path ( '|' Path )*
Path     ::=     ('.//' | '//' | '/' )? Step ( '/' Step )*
Step     ::=     '.' | NameTest
NameTest ::=     QName | '*' | NCName ':' '*'

and for readability — because we love readability — whitespace may be used in selector XPath expressions even though the grammar above doesn't explicitly allow it. whitespace can be freely added within patterns before or after any token, where:

token     ::=     '.' | '/' | '//' | '|' | NameTest

heads up bestie: no predicates or attribute tests are allowed. none. not a single one. 🙈

Patterns are particularly useful for stream parsing, which you get via the XML::LibXML::Reader interface. streaming girlies, this one's for you. 💜

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🎀 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 up there ⬆️) plus an optional HASH reference mapping prefixes to namespace URIs. it hands you back a compiled pattern object. iconic. ✨

important: if the document has a default namespace, it must still be given a prefix in order to be matched (as demanded by the XPath 1.0 specification). yes, even though it's the default namespace. that's just how XPath 1.0 woke up and chose violence. 💀

so for example, to match an element "<a xmlns="http://foo.bar"</a>", you'd want a pattern like this:

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

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🌈 matchesNode($node) 🌈

$bool = $pattern->matchesNode($node);

Give it an XML::LibXML::Node object and it returns a true value if the node is matched by the compiled pattern expression. that's the whole thing. slay. 🫶

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👑 SEE ALSO 👑

XML::LibXML::Reader — for other methods involving compiled patterns. go read that one too bestie, they're a package deal. 💖

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⭐ AUTHORS ⭐

Matt Sergeant, Christian Glahn, Petr Pajas

the literal main characters. 🧚

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🍓 VERSION 🍓

2.0213

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💅 COPYRIGHT 💅

2001-2007, AxKit.com Ltd.

2002-2006, Christian Glahn.

2006-2009, Petr Pajas.

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🔥 LICENSE 🔥

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

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and that's the whole page babes!! 🌸 this was perl v5.42.2, dated 2026-05-25, and you just read XML::Li...Pattern(3) — tysm for coming to my ted talk, go match some nodes, no cap 💖✨🎀🦋