if(_SARISSA_HAS_DOM_FEATURE && document.implementation.hasFeature("XPath", "3.0")){

    function SarissaNodeList(i){
        this.length = i;
    };
    SarissaNodeList.prototype = new Array(0);
    SarissaNodeList.prototype.constructor = Array;
    SarissaNodeList.prototype.item = function(i) {
        return (i < 0 || i >= this.length)?null:this[i];
    };
    SarissaNodeList.prototype.expr = "";
    XMLDocument.prototype.setProperty  = function(x,y){};
    Sarissa.setXpathNamespaces = function(oDoc, sNsSet) {
        oDoc._sarissa_useCustomResolver = true;
        var namespaces = sNsSet.indexOf(" ")>-1?sNsSet.split(" "):new Array(sNsSet);
        oDoc._sarissa_xpathNamespaces = new Array(namespaces.length);
        for(var i=0;i < namespaces.length;i++){
            var ns = namespaces[i];
            var colonPos = ns.indexOf(":");
            var assignPos = ns.indexOf("=");
            if(colonPos == 5 && assignPos > colonPos+2){
                var prefix = ns.substring(colonPos+1, assignPos);
                var uri = ns.substring(assignPos+2, ns.length-1);
                oDoc._sarissa_xpathNamespaces[prefix] = uri;
            }else{
                throw "Bad format on namespace declaration(s) given";
            };
        };
    };
    XMLDocument.prototype._sarissa_useCustomResolver = false;
    XMLDocument.prototype._sarissa_xpathNamespaces = new Array();
    XMLDocument.prototype.selectNodes = function(sExpr, contextNode){
        var nsDoc = this;
        var nsresolver = this._sarissa_useCustomResolver
        ? function(prefix){
            var s = nsDoc._sarissa_xpathNamespaces[prefix];
            if(s)return s;
            else throw "No namespace URI found for prefix: '" + prefix+"'";
            }
        : this.createNSResolver(this.documentElement);
            var oResult = this.evaluate(sExpr,
                    (contextNode?contextNode:this),
                    nsresolver,
                    XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
        var nodeList = new SarissaNodeList(oResult.snapshotLength);
        nodeList.expr = sExpr;
        for(var i=0;i<nodeList.length;i++)
            nodeList[i] = oResult.snapshotItem(i);
        return nodeList;
    };
    Element.prototype.selectNodes = function(sExpr){
        var doc = this.ownerDocument;
        if(doc.selectNodes)
            return doc.selectNodes(sExpr, this);
        else
            throw "Method selectNodes is only supported by XML Elements";
    };
    XMLDocument.prototype.selectSingleNode = function(sExpr, contextNode){
        var ctx = contextNode?contextNode:null;
        sExpr = "("+sExpr+")[1]";
        var nodeList = this.selectNodes(sExpr, ctx);
        if(nodeList.length > 0)
            return nodeList.item(0);
        else
            return null;
    };
    Element.prototype.selectSingleNode = function(sExpr){
        var doc = this.ownerDocument;
        if(doc.selectSingleNode)
            return doc.selectSingleNode(sExpr, this);
        else
            throw "Method selectNodes is only supported by XML Elements";
    };
    Sarissa.IS_ENABLED_SELECT_NODES = true;
};