<?php

function getElementsByClassName(DOMDocument $DOMDocument, $ClassName)
{
    $Elements = $DOMDocument -> getElementsByTagName("*");
    $Matched = array();

    foreach($Elements as $node)
    {
        if( ! $node -> hasAttributes())
            continue;

        $classAttribute = $node -> attributes -> getNamedItem('class');

        if( ! $classAttribute)
            continue;

        $classes = explode(' ', $classAttribute -> nodeValue);

        if(in_array($ClassName, $classes))
            $Matched[] = $node;
    }

    return $Matched;
}