Savage.plugin(function (Savage, Element, Paper, glob) {
    var names = {},
        reUnit = /[a-z]+$/i,
        Str = String;
    names.stroke = names.fill = "colour";
    function getEmpty(item) {
        var l = item[0];
        switch (l.toLowerCase()) {
            case "t": return [l, 0, 0];
            case "m": return [l, 1, 0, 0, 1, 0, 0];
            case "r": if (item.length == 4) {
                return [l, 0, item[2], item[3]];
            } else {
                return [l, 0];
            }
            case "s": if (item.length == 5) {
                return [l, 1, 1, item[3], item[4]];
            } else if (item.length == 3) {
                return [l, 1, 1];
            } else {
                return [l, 1];
            }
        }
    }
    function equaliseTransform(t1, t2) {
        t2 = Str(t2).replace(/\.{3}|\u2026/g, t1);
        t1 = Savage.parseTransformString(t1) || [];
        t2 = Savage.parseTransformString(t2) || [];
        var maxlength = Math.max(t1.length, t2.length),
            from = [],
            to = [],
            i = 0, j, jj,
            tt1, tt2;
        for (; i < maxlength; i++) {
            tt1 = t1[i] || getEmpty(t2[i]);
            tt2 = t2[i] || getEmpty(tt1);
            if ((tt1[0] != tt2[0]) ||
                (tt1[0].toLowerCase() == "r" && (tt1[2] != tt2[2] || tt1[3] != tt2[3])) ||
                (tt1[0].toLowerCase() == "s" && (tt1[3] != tt2[3] || tt1[4] != tt2[4]))
                ) {
                return;
            }
            from[i] = [];
            to[i] = [];
            for (j = 0, jj = Math.max(tt1.length, tt2.length); j < jj; j++) {
                j in tt1 && (from[i][j] = tt1[j]);
                j in tt2 && (to[i][j] = tt2[j]);
            }
        }
        return {
            from: path2array(from),
            to: path2array(to),
            f: getPath(from)
        };
    }
    function getNumber(val) {
        return val;
    }
    function getUnit(unit) {
        return function (val) {
            return +val.toFixed(3) + unit;
        };
    }
    function getColour(clr) {
        return Savage.rgb(clr[0], clr[1], clr[2]);
    }
    function getPath(path) {
        var k = 0, i, ii, j, jj, out, a, b = [];
        for (i = 0, ii = path.length; i < ii; i++) {
            out = "[";
            a = ['"' + path[i][0] + '"'];
            for (j = 1, jj = path[i].length; j < jj; j++) {
                a[j] = "val[" + (k++) + "]";
            }
            out += a + "]";
            b[i] = out;
        }
        return Function("val", "return Savage.path.toString.call([" + b + "])");
    }
    function path2array(path) {
        var out = [];
        for (var i = 0, ii = path.length; i < ii; i++) {
            for (var j = 1, jj = path[i].length; j < jj; j++) {
                out.push(path[i][j]);
            }
        }
        return out;
    }
    Element.prototype.equal = function (name, b) {
        var A, B, a = Str(this.attr(name) || "");
        if (a == +a && b == +b) {
            return {
                from: +a,
                to: +b,
                f: getNumber
            };
        }
        if (names[name] == "colour") {
            A = Savage.color(a);
            B = Savage.color(b);
            return {
                from: [A.r, A.g, A.b, A.opacity],
                to: [B.r, B.g, B.b, B.opacity],
                f: getColour
            };
        }
        if (name == "transform" || name == "gradientTransform" || name == "patternTransform") {
            // TODO: b could be an SVG transform string or matrix
            return equaliseTransform(a.local, b);
        }
        if (name == "d" || name == "path") {
            A = Savage.path.toCubic(a, b);
            return {
                from: path2array(A[0]),
                to: path2array(A[1]),
                f: getPath(A[0])
            };
        }
        var aUnit = a.match(reUnit),
            bUnit = b.match(reUnit);
        if (aUnit && aUnit == bUnit) {
            return {
                from: parseFloat(a),
                to: parseFloat(b),
                f: getUnit(aUnit)
            };
        } else {
            return {
                from: this.asPX(name),
                to: this.asPX(name, b),
                f: getNumber
            };
        }
    };
});