README

Functional XML-reader for PHP 5.3+.

A somewhat different approach to reading/parsing XML files with PHP, using a hierarchy of anonymous functions (closures) reflecting the hierarchy of the XML document itself.

This is useful when reading structured XML documents - e.g. XML documents with a predictable structure. It's probably less than enjoyable when reading unstructured documents, such as XHTML documents.

Parsing happens on-the-fly, e.g. avoiding the overhead of loading an entire document into memory and performing repetitive queries against it. This approach is memory efficient, enabling you to parse very large documents in a streaming fashion - it is not super fast (throughput ~500 KB/sec on my laptop) but XML parsing is never truly fast, so you should definitely always cache the parsed results.

Usage

Let's say you wish to read the following XML file:

<?xml version="1.0" encoding="UTF-8"?>
<cats>
    <cat name="whiskers">
        <kitten name="mittens"/>
    </cat>
    <cat name="tinker">
        <kitten name="binky"/>
    </cat>
</cats>

Your reader might look something like this:

$doc = new Parser();

$doc['cats/cat'] = function (Visitor $cat, $name) {
    echo "a cat named: {$name}\n";

    $cat['kitten'] = function ($name) {
        echo "a kitten named: {$name}\n";
    };
};

$doc->parseFile('my_cats.xml');

The output would be this:

a cat named: whiskers
a kitten named: mittens
a cat named: tinker
a kitten named: binky

If it's not obvious, the path cats/cat designates a <cat> node inside a <cats> node.

You can also match text-nodes, e.g. a path like foo/bar#text will match YO in <foo><bar>YO</bar></foo>.

And finally, you can use #end to match closing tags, if needed.

Incidentally, I don't actually have cats - but if I did, you can bet those would be their names.

See "test.php" and "example/cd_catalog.php" for more examples of how to use this.