document.getElementsBySelector = function(css)
{
    var xpath = cssToXPath(css);

    var result = this.evaluate(xpath, this, null, XPathResult.ANY_TYPE, null);

    var nodes = [];
    for (var item = result.iterateNext(); item; item = result.iterateNext())
        nodes.push(item);

    return nodes;
}

function cssToXPath(rule)
{
    var regElement = /^([#.]?)([a-z0-9\\*_-]*)((\|)([a-z0-9\\*_-]*))?/i;
    var regAttr1 = /^\[([^\]]*)\]/i;
    var regAttr2 = /^\[\s*([^~=\s]+)\s*(~?=)\s*"([^"]+)"\s*\]/i;
    var regPseudo = /^:([a-z_-])+/i;
    var regCombinator = /^(\s*[>+\s])?/i;
    var regComma = /^\s*,/i;

    var index = 1;
    var parts = ["//", "*"];
    var lastRule = null;
    
    while (rule.length && rule != lastRule)
    {
        lastRule = rule;

        // Trim leading whitespace
        rule = rule.replace(/^\s*|\s*$/g,"");
        if (!rule.length)
            break;
        
        // Match the element identifier
        var m = regElement.exec(rule);
        if (m)
        {
            if (!m[1])
            {
                // XXXjoe Namespace ignored for now
                if (m[5])
                    parts[index] = m[5];
                else
                    parts[index] = m[2];
            }
            else if (m[1] == '#')
                parts.push("[@id='" + m[2] + "']"); 
            else if (m[1] == '.')
                parts.push("[contains(@class, '" + m[2] + "')]"); 
            
            rule = rule.substr(m[0].length);
        }
        
        // Match attribute selectors
        m = regAttr2.exec(rule);
        if (m)
        {
            if (m[2] == "~=")
                parts.push("[contains(@" + m[1] + ", '" + m[3] + "')]");
            else
                parts.push("[@" + m[1] + "='" + m[3] + "']");

            rule = rule.substr(m[0].length);
        }
        else
        {
            m = regAttr1.exec(rule);
            if (m)
            {
                parts.push("[@" + m[1] + "]");
                rule = rule.substr(m[0].length);
            }
        }
        
        // Skip over pseudo-classes and pseudo-elements, which are of no use to us
        m = regPseudo.exec(rule);
        while (m)
        {
            rule = rule.substr(m[0].length);
            m = regPseudo.exec(rule);
        }
        
        // Match combinators
        m = regCombinator.exec(rule);
        if (m && m[0].length)
        {
            if (m[0].indexOf(">") != -1)
                parts.push("/");
            else if (m[0].indexOf("+") != -1)
                parts.push("/following-sibling::");
            else
                parts.push("//");

            index = parts.length;
            parts.push("*");
            rule = rule.substr(m[0].length);
        }
        
        m = regComma.exec(rule);
        if (m)
        {
            parts.push(" | ", "//", "*");
            index = parts.length-1;
            rule = rule.substr(m[0].length);
            
        }
    }
    
    var xpath = parts.join("");
    return xpath;
}