def merge_streams(streams):
"""Merges sorted streams into one sorted list.
:param streams: list of MyStream objects.
:return: sorted list of integers.
"""
min_buffer = PriorityQueue()
all_streams_are_empty = False
iterations = 0
next_i = None
while not all_streams_are_empty:
all_streams_are_empty = True
for i, stream in enumerate(streams):
while not stream.empty:
if (next_i is not None) and i != next_i:
break
new_int = stream.pop()
if new_int is not None:
min_buffer.insert((i, new_int))
if iterations < 1: # first step is to get the top
# "layer" of all streams
break
else: # if we already have our top "layer"
# we will run the main sorting algorithm
next_i, min_int = min_buffer.pop_min()
yield min_int # return minimums one by one
next_i = None if streams[next_i].empty else next_i
all_streams_are_empty = all_streams_are_empty and stream.empty
iterations += 1
while len(min_buffer): # when all streams became empty
# we just ineratively pop all heap content
yield min_buffer.pop_min()
print ('DEBUG: heap (list) of real size == %s were allocated '
'during sorting.' % len(min_buffer.heap))
