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# Regina - A Normal Surface Theory Calculator
# Fine-grained timing for Python iteration
#
# The motivation behind this test is that, in January 2023, SageMath was
# found to impose a significant time penalty on catching a StopIteration
# exception. This is unfortunate because this is the mechanism by which
# Python iteration is meant to work. The issue does appear to be specific
# to SageMath, since (using this script) it seems that running the same code
# in a plain Python interpreter does _not_ exhibit the same time penalty.
#
# Copyright (c) 2023-2025, Ben Burton
# For further details contact Ben Burton (bab@debian.org).
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of the
# License, or (at your option) any later version.
#
# As an exception, when this program is distributed through (i) the
# App Store by Apple Inc.; (ii) the Mac App Store by Apple Inc.; or
# (iii) Google Play by Google Inc., then that store may impose any
# digital rights management, device limits and/or redistribution
# restrictions that are required by its terms of service.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#
import regina
import time
t = regina.Example3.weberSeifert()
e = t.edge(0)
print('All times in ms')
# Note: can stop iteration via PyErr_SetString(PyExc_StopIteration, "")
print('--- Start timer: manual iteration ---')
start = time.time()
it = e.embeddings().__iter__()
# print(type(it))
try:
while True:
emb = it.__next__()
print(emb, (time.time() - start) * 1000)
except:
print('Except:', (time.time() - start) * 1000)
it = None
print('TOTAL MANUAL:', (time.time() - start) * 1000)
print('--- Start timer: loop iteration ---')
start = time.time()
for emb in e.embeddings():
print(emb, (time.time() - start) * 1000)
print('TOTAL LOOP:', (time.time() - start) * 1000)
print('--- Start timer: loop iteration over range() ---')
start = time.time()
for i in range(e.degree()):
print(e.embedding(i), (time.time() - start) * 1000)
print('TOTAL RANGE:', (time.time() - start) * 1000)
class It:
count = 0
limit = 0
def __init__(self, edge):
self.limit = edge.degree()
def __iter__(self):
return self
def __next__(self):
if self.count == self.limit:
raise StopIteration
ret = self.count
self.count = self.count + 1
return ret
print('--- Start timer: pure python iteration ---')
start = time.time()
for i in It(e):
print(e.embedding(i), (time.time() - start) * 1000)
print('TOTAL PURE PYTHON:', (time.time() - start) * 1000)
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