(function(root) {
    "use strict";
    var RED = 0, BLACK = 1;
    function Tree(color, left, key, value, right) {
        this.color = color;
        this.left = left;
        this.right = right;
        this.key = key;
        this.value = value;
    }
    Tree.prototype.has = function(key) {
        if (key < this.key) {
            return this.left.has(key);
        } else if (key > this.key) {
            return this.right.has(key);
        } else {
            return true;
        }
    };
    Tree.prototype.add = function(key, value) {
        if (key < this.key) {
            return this.$Tree_balance(this.color, this.left.add(key, value), this.key, this.value, this.right);
        } else if (key > this.key) {
            return this.$Tree_balance(this.color, this.left, this.key, this.value, this.right.add(key, value));
        } else {
            return new Tree(this.color, this.left, this.key, value, this.right);
        }
    };
    Tree.prototype.$Tree_balance = function(color, left, key, value, right) {
        if (color === BLACK) {
            if (left instanceof Tree && left.color === RED) {
                if (left.left instanceof Tree && left.left.color === RED) {
                    var level2 = left.left, l = new Tree(BLACK, level2.left, level2.key, level2.value, level2.right), r = new Tree(BLACK, left.right, key, value, right);
                    return new Tree(RED, l, left.key, left.value, r);
                } else if (left.right instanceof Tree && left.right.color === RED) {
                    var level2 = left.right, l = new Tree(BLACK, left.left, left.key, left.value, level2.left), r = new Tree(BLACK, level2.right, key, value, right);
                    return new Tree(RED, l, level2.key, level2.value, r);
                }
            } else if (right instanceof Tree && right.color === RED) {
                if (right.left instanceof Tree && right.left.color === RED) {
                    var level2 = right.left, l = new Tree(BLACK, left, key, value, level2.left), r = new Tree(BLACK, level2.right, right.key, right.value, right.right);
                    return new Tree(RED, l, level2.key, level2.value, r);
                } else if (right.right instanceof Tree && right.right.color === RED) {
                    var level2 = right.right;
                    l = new Tree(BLACK, left, key, value, right.left);
                    r = new Tree(BLACK, level2.left, level2.key, level2.value, level2.right);
                    return new Tree(RED, l, right.key, right.value, level2.right);
                }
            }
        }
        return new Tree(color, left, key, value, right);
    };
    Tree.prototype.get = function(key) {
        if (key < this.key) {
            return this.left.get(key);
        } else if (key > this.key) {
            return this.right.get(key);
        } else {
            return this.value;
        }
    };
    Tree.prototype.count = function() {
        return this.left.count() + 1 + this.right.count();
    };
    Tree.prototype.iter = function(fn) {
        this.left.iter(fn);
        fn(this.key, this.value);
        this.right.iter(fn);
    };
    Tree.prototype.map = function(fn) {
        var left = this.left.map(fn), value = fn(this.key, this.value), right = this.right.map(fn);
        return new Tree(this.color, left, this.key, value, right);
    };
    Tree.prototype.reduce = function(fn, acc) {
        acc = this.left.reduce(fn, acc);
        acc = fn(this.key, this.value, acc);
        return this.right.reduce(fn, acc);
    };
    Tree.prototype.toObject = function() {
        var obj = {};
        this.iter(function(k, v) {
            obj[k] = v;
        });
        return obj;
    };
    function Empty() {}
    Empty.prototype.has = function(key) {
        return false;
    };
    Empty.prototype.add = function(key, value) {
        return new Tree(RED, empty, key, value, empty);
    };
    Empty.prototype.get = function(key) {
        return null;
    };
    Empty.prototype.count = function() {
        return 0;
    };
    Empty.prototype.iter = function(fn) {};
    Empty.prototype.map = function(fn) {
        return this;
    };
    Empty.prototype.reduce = function(fn, acc) {
        return acc;
    };
    Empty.prototype.toObject = function() {
        return {};
    };
    var empty = new Empty();
    function fromObject(obj) {
        var t = empty;
        for (var key in obj) {
            if (obj.hasOwnProperty(key)) {
                t = t.add(key, obj[key]);
            }
        }
        return t;
    }
    var moduleObj = {
        empty: empty,
        RBTree: Tree,
        fromObject: fromObject
    };
    if (typeof exports !== "undefined") {
        if (typeof module !== "undefined" && module.exports) {
            exports = module.exports = moduleObj;
        } else {
            root.rbtree = moduleObj;
        }
    }
})(this);