dom_varimport: a simple PHP extension to convert nested arrays into DOMDocument
Dmitry Koterov, http://en.dklab.ru/lib/dom_varimport/
License: PHP License 3.01

Motivation

Some of projects use XSLT as a templating engine. To build XML for such engines, we need a very fast and memory efficient way to convert PHP nested arrays and objects into DOMDocument object. Also, produced XML should be straight-forward and as simple as it could be (BTW XMLRPC, SOAP and other XML-based formats are quite sloppy in this case). So dom_varimport has been introduced: it produces DOMDocument from a nested array near 20 times faster than a hand-made code in native PHP (1 MB XML with thousands of nodes could be generated in 1-2 ms).

How to build

phpize
./configure
make
make test
make install  # or copy modules/dom_varimport.so manually
phpize --clean

Then, add the following to your php.ini file:

extension=dom_varimport.so

RPMs for Fedora, RHEL and CentOS are available in remi repository.

Synopsis

The code:

$doc = new DOMDocument();
$doc->formatOutput = true;
dom_varimport(
    $doc,
    array(
        "a" => 111,
        123,
        0.5,
        "arr" => array("1a" => "1a"),
        "obj" => (object)array("prop" => "val"),
        true,
        false,
        "b" => null,
        "empty" => array(),
    ),
    "root", // optional, defaults to "root"
    "item", // optional, defaults to "item", if NULL - invalid tag names are hidden
    "key",  // optional, defaults to "key", if NULL - no key attributes are inserted
    false   // optional, if true - show notices when keys are not valid XML elements
);
echo $doc->saveXML();

prints:

<?xml version="1.0"?>
<root>
  <a key="a">111</a>           <!-- plain key=value -->
  <item key="0">123</item>     <!-- numeric keys are "item" tags -->
  <item key="1">0.5</item>     <!-- double -->
  <arr key="arr">              <!-- nested array -->
    <item key="1a">1a</item>   <!-- invalid tag names are converted to "item" -->
  </arr>
  <obj key="obj">              <!-- nested object -->
    <prop key="prop">val</prop>
  </obj>
  <item key="2">1</item>       <!-- true converts to 1 -->
  <item key="3"/>              <!-- false converts to an empty string -->
  <b key="b"/>                 <!-- null also converts to an empty string -->
  <empty key="empty"/>         <!-- empty array is an empty element -->
</root>