notes_on_generators.py

"""
Reference: https://www.python-course.eu/python3_generators.php
"""


def fibonacci():
	""" generates fib sequence """
	a,b = 0,1
	while 1:
		yield a
		a,b = b, a + b

def test_fib():
	counter = 0
	for i in fibonacci():
		print(i)
		if counter > 12:
			break
		counter += 1


def gen_with_return():
	yield 1
	return  # having return in generator is equivalent of raising StopIteration


def test_gen_with_return():
	g = gen_with_return()
	print(next(g))
	print(next(g))


def send_in_coro():
	"""
	Coroutine can accept objects.
	this demo intended to highlight this concept

	"""
	print("initialized generator")
	x = yield
	# do something with x
	print("got value for x: {}".format(x))
	yield x
	yield x


def test_send_in_coro():
	g = send_in_coro()
	next(g)
	print(g.send(10))
	print(next(g))


def infinite_looper(word: str):
	"""
	Demoes how to send into generator messages 
	"""
	count = 0
	while True:
		if count >= len(word):
			count = 0
		message = yield word[count]
		if message != None:
			count = 0 if message < 0 else message
		else:
			count += 1


def test_infinite_looper():
	g = infinite_looper("abcdefg")
	print(next(g))
	print(g.send(1))
	print(g.send(0))
	print(g.send(6))




def main():
	# test_fib()
	# test_gen_with_return()
	# test_send_in_coro()
	test_infinite_looper()

	

if __name__ == '__main__':
	main()