Express Python yield in JavaScript or Java

I thought about how to express the yield of Python in Java and JavaScript.

This time, I didn't try to make something practical, but I thought about how to replace it if I made a code generator.

For the time being, I tried to use this as a subject.

http://ideone.com/PG6xOJ

# your code goes here
def Generator(n):
	yield 1;
	
	idx = 0
	while idx < n:
		yield 2
		idx += 1

	yield 3
	
g = Generator(5)
for x in g:
	print x

A little thought policy

Loops can be replaced with something like a goto statement
A goto statement can be expressed by combining a while statement and a switch statement.
Save the yielded position as state

I wrote it in JavaScript with this policy.

http://ideone.com/24L64n

// your code goes here
function Generator(n) {
	var ctx = { state:0, idx:0 };

	return function() {
		while (1) {
			switch (ctx.state) {
				case 0:
					ctx.state = 1;
					return 1;
				
				case 1:
					if (ctx.idx < n) {
						ctx.idx++;
						return 2;
					}

					ctx.state = 2;
					break;
					
				case 2:
					ctx.state = -1;
					return 3;
				
				default:
					return undefined;
			}
		}
	};
}

(function() {
	var g = Generator(5);
	while (1) {
		var x = g();
		if (x === undefined)
			break;
		print(x);
	}
})();

I wrote it in Java as well.

http://ideone.com/YnxHkv

/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	private static class Generator {
		final int n_;
		int state_ = 0, idx_ = 0;
		boolean completed_ = false;
		
		Generator(int n) {
			n_ = n;
		}
		
		int generate() {
			while (true) switch (state_) {
				case 0:
					state_ = 1; return 1;
					
				case 1:
					if (idx_ < n_) {
						idx_++;
						return 2;
					}
					else {
						state_ = 2;
					}
					break;
					
				case 2:
					completed_ = true;
					return 3;
			}
		}
		
		boolean isCompleted() { return completed_; }
	}

	public static void main (String[] args) throws java.lang.Exception
	{
		Generator g = new Generator(5);
		while (! g.isCompleted()) {
			int x = g.generate();
			System.out.println(x + "");
		}
	}
}

Both are moving for the time being.

Do you already have a code generator like this?

In an era when the yield statement can be used normally in a browser, you don't have to think about this.