XML::LibXML::Devel(3) User Contributed Perl DocumentationXML::LibXML::Devel(3)NAMEXML::LibXML::Devel - makes functions from LibXML.xs available
SYNOPSIS
// C functions
xmlNode *return_node();
void receive_node(xmlNode *);
# XS Code
void *
xs_return_node
CODE:
RETVAL = return_node();
OUTPUT:
RETVAL
void
xs_receive_node
void *n
CODE:
receive_node(n);
# Perl code
use XML::LibXML::Devel;
sub return_node
{
my $raw_node = xs_return_node();
my $node = XML::LibXML::Devel::node_to_perl($raw_node);
XML::LibXML::Devel::refcnt_inc($raw_node);
return $node;
}
sub receive_node
{
my ($node) = @_;
my $raw_node = XML::LibXML::Devel::node_from_perl($node);
xs_receive_node($raw_node);
XML::LibXML::Devel::refcnt_inc($raw_node);
}
DESCRIPTION
"XML::LibXML::Devel" makes functions from LibXML.xs available that are
needed to wrap libxml2 nodes in and out of XML::LibXML::Nodes. This
gives cleaner dependencies than using LibXML.so directly.
To XS a library that uses libxml2 nodes the first step is to do this so
that xmlNodePtr is passed as void *. These raw nodes are then turned
into libxml nodes by using this Devel functions.
Be aware that this is currently rather experimental. The function names
may change if I XS more functions and introduce a reasonable naming
convention.
Be also aware that this is a great tool to cause segfaults and
introduce memory leaks.
FUNCTIONS
NODE MANAGEMENT
node_to_perl
node_to_perl($raw_node);
Returns a LibXML::Node object. This has a proxy node with a reference
counter and an owner attached. The raw node will be deleted as soon as
the reference counter reaches zero. If the C library is keeping a
pointer to the raw node, you need to call refcnt_inc immediately. You
also need to replace xmlFreeNode by a call to refcnt_dec.
node_to_perl
node_from_perl($node);
Returns a raw node. This is a void * pointer and you can do nothing
but passing it to functions that treat it as an xmlNodePtr. The raw
node will be freed as soon as its reference counter reaches zero. If
the C library is keeping a pointer to the raw node, you need to call
refcnt_inc immediately. You also need to replace xmlFreeNode by a
call to refcnt_dec.
refcnt_inc
refcnt_inc($raw_node);
Increments the raw nodes reference counter. The raw node must already
be known to perl to have a reference counter.
refcnt_dec
refcnt_dec($raw_node);
Decrements the raw nodes reference counter and returns the value it
had before. if the counter becomes zero or less, this method will free
the proxy node holding the reference counter. If the node is part of
a subtree, refcnt_dec will fix the reference counts and delete the
subtree if it is not required any more.
refcnt
refcnt($raw_node);
Returns the value of the reference counter.
fix_owner
fix_owner($raw_node, $raw_parent);
This functions fixes the reference counts for an entire subtree. it
is very important to fix an entire subtree after node operations where
the documents or the owner node may get changed. this method is aware
about nodes that already belong to a certain owner node.
MEMORY DEBUGGING
$ENV{DEBUG_MEMORY}
BEGIN {$ENV{DEBUG_MEMORY} = 1;};
use XML::LibXML;
This turns on libxml2 memory debugging. It must be set before
XML::LibXML is loaded.
mem_used
mem_used();
Returns the number of bytes currently allocated.
EXPORT
None by default.
SEE ALSO
This was created to support the needs of Apache2::ModXml2. So this can
serve as an example.
AUTHOR
Joachim Zobel <jz-2011@heute-morgen.de>
COPYRIGHT AND LICENSE
Copyright (C) 2011 by Joachim Zobel
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, either Perl version 5.10.1 or, at
your option, any later version of Perl 5 you may have available.
perl v5.14.2 2012-01-08 XML::LibXML::Devel(3)
