NAME¶
XML::LibXML::LazyBuilder - easy and lazy way to create XML documents for
XML::LibXML
SYNOPSIS¶
use XML::LibXML::LazyBuilder;
{
package XML::LibXML::LazyBuilder;
$d = DOM (E A => {at1 => "val1", at2 => "val2"},
((E B => {}, ((E "C"),
(E D => {}, "Content of D"))),
(E E => {}, ((E F => {}, "Content of F"),
(E "G")))));
}
DESCRIPTION¶
This module significantly abridges the overhead of working with XML::LibXML by
enabling developers to write concise, nested structures that evaluate into
XML::LibXML objects.
FUNCTIONS¶
DOM¶
my $doc = DOM (E $name => \%attr, @children), $var, $enc;
# With defaults, this is shorthand for:
my $doc = E($name => \%attr,
@children)->(XML::LibXML::Document->new);
Generates a "XML::LibXML::Document" object. The first argument is a
"CODE" reference created by "E". $var represents the
version in the XML declaration, and $enc is the character encoding, which
default to 1.0 and "utf-8", respectively.
my $sub = E tagname => \%attr, @children;
my $doc = DOM $sub;
This function returns a "CODE" reference which itself evaluates to an
XML::LibXML::Element object. The function returned from "E" expects
an XML::LibXML::Document object as its only argument, which is conveniently
provided by "DOM".
Using "E" with an existing XML document
"E" can also be used to compose the subtree of an existing XML
element. Instead of supplying a name as the first argument of "E",
supply an XML::LibXML::Element object. Note, however, that any attributes
present in that object will be overwritten by "\%attr", and the
supplied element
must be bound to a document, or the function will
croak. This is to ensure that the subtree is connected to the element's
document and not some other document.
As such, any XML::LibXML::Document object passed into the function returned by
"E" will be ignored in favour of the document connected to the
supplied element. This also means that "E($elem => \%attr,
@children)->($ignored_dom);" can be called in void context, because it
will just return $elem.
# parse an existing XML document
my $doc = XML::LibXML->load_xml(location => 'my.xml');
# find an element of interest
my ($existing) = $doc->findnodes('//some-element[1]');
# prepare the subtree
my $sub = E $existing => \%attr, @children;
# this will overwrite the attributes of $existing and append
# @children to it; normally the document is passed as an argument
# but in this case it would be derived from $existing.
$sub->();
# we also don't care about the output of this function, since it
# will have modified $doc, which we already have access to.
Note as well that members of @children can be XML::LibXML::Node objects.
Namespaces
Qualified element names and namespace declaration attributes will behave largely
as expected. This means that:
E 'foo:bar' => { 'xmlns:foo' => 'urn:x-foo:' }; # ...
...will properly induct the generated element into the "foo"
namespace. E attempts to infer the namespace mapping from the document, so
child elements with qualified names will inherit the mapping from their
ancestors.
CAVEAT: When "E" is executed in the
context of an element name rather than with an existing
XML::LibXML::Element, the namespace mappings are scanned from the context of
the document root, in document order. This means that the last namespace
declaration that appears in the existing document (depth-first) will occupy
the given prefix. When an existing element is passed into "E", the
namespace search begins there and ascends to the root. If you have any
concerns about collisions of namespace declarations, use that form
instead.
my $sub = P target => { key => 'value' }, @othertext;
This function returns a "CODE" reference which returns a processing
instruction. If you pass in a HASH reference as the first argument, it will be
turned into key-value pairs using double-quotes on the values. This means you
have to take care of your own escaping of any double quotes that may be in the
values. The rest of the arguments are concatenated into a string (intended to
behave like "print" in perlfunc, which means if you want spaces
between them, you likewise need to add them yourself).
my $sub = C @text;
This function creates a "CODE" reference which returns a comment.
Again, @text is simply concatenated, so if you wish to do any additional
formatting, do so before passing it in.
my $sub = D @text;
This function creates a "CODE" reference which returns a CDATA
section. Works identically to "C".
my $sub = F @children;
This function creates a "CODE" reference which returns a document
fragment. Since "DOM" can only accept a single node-generating
function, it is particularly useful for the following idiom:
my $doc = DOM F(
(P 'xml-stylesheet' => { type => 'text/xsl', href => '/foo.xsl' }),
(E mydoc => {}, @children));
Which produces:
<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type="text/xsl" href="/foo.xsl"?>
<mydoc>...</mydoc>
DTD¶
my $sub = DTD $name => $public, $system;
This function creates a "CODE" reference which returns a DTD
declaration. Both $public and $system can be "undef".
EXPORT¶
None by default.
:all¶
Exports "E", "P", "C", "D",
"F" and "DOM".
EXAMPLES¶
If you nest your code in braces and use a "package" declaration like
so, you can avoid polluting the calling package's namespace:
my $d;
{
package XML::LibXML::LazyBuilder;
$d = DOM (E A => {at1 => "val1", at2 => "val2"},
((E B => {}, ((E "C"),
(E D => {}, "Content of D"))),
(E E => {}, ((E F => {}, "Content of F"),
(E "G")))));
}
Then, "$d->toString" will generate XML like this:
<?xml version="1.0" encoding="utf-8"?>
<A at1="val1" at2="val2"><B><C/><D>Content of D</D></B><E><F>Content of F</F><G/></E></A>
SEE ALSO¶
XML::LibXML
The Python module lxml.etree <
http://lxml.de/tutorial.html>
AUTHOR¶
Toru Hisai <mailto:toru@torus.jp>
Namespace and non-element support by Dorian Taylor
<mailto:dorian@cpan.org>
COPYRIGHT AND LICENSE¶
Copyright (C) 2008, 2012 by Toru Hisai
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself, either Perl version 5.10.0 or, at your option,
any later version of Perl 5 you may have available.