Combinator.js

var Combinator = function (opts) {
    var combinations = [];

    function combine(current, remainder) {
        if (remainder.length === 0) {
            if (current.length >= (opts.min || 0) &&
                current.length <= (opts.max || current.length))
                combinations.push(current);
        } else {
            combine(current.concat(remainder[0]), remainder.slice(1, remainder.length));
            combine(current, remainder.slice(1, remainder.length));
        }
        return this;
    }
    return {
        combinations: combinations,
        combine: combine
    }
}

module.exports = Combinator;