Self-Contained Generator Function (JavaScript)

Question

Create a function that takes in a generator function as its only parameter, and returns an object that can be used as both as a generator and a generator function for said generator. The idea is to be able to create an object that behaves like a generator (that is, it follows the iteration protocols) but also has the ability to restart itself.

For the rules:

• SelfGenerator is the function you're creating.

• sg is the return value of SelfGenerator.

• genFunc is the parameter passed into SelfGenerator.

Rules:

• sg must have a start method that returns a generator that behaves the same as the generator that would be returned by genFunc.

• sg.start must accept parameters that will be used to create the generator it returns such that it is the same as the generator returned by passing those parameters into genFunc.

• After sg.start(...params) has been executed, if genFunc(...params)[prop] is callable, then sg[prop] is also callable and will return the same value.

• sg.start(...params).next(value); let a = sg.next(); and sg.start(...params); sg.next(value); let a = sg.next(); must end up with the same value for a.

• smallest source code wins

Example:

let sg = SelfGenerator(function*(n) {
    yield n;
    yield n + 1;
    yield n + 2;
});

sg.start(1);         // Generator
sg.next();           // {value: 1, done: false}
sg.next();           // {value: 2, done: false}
sg.start(10).next(); // {value: 10, done: false}
sg.next();           // {value: 11, done: false}