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import unittest
from bitarray import bitarray
PATTERN = [0, 1, 4, 8, 16, 24, 32, 40, 48, 56, 64, 76, 88, 100, 112, 124, 136]
def get_alloc(a):
return a.buffer_info()[4]
def resize(a, n):
increase = n - len(a)
if increase > 0:
a.extend(bitarray(increase))
elif increase < 0:
del a[n:]
def show(a):
info = a.buffer_info()
size = info[1]
alloc = info[4]
print('%d %d' % (size, alloc))
class ResizeTests(unittest.TestCase):
def test_pattern(self):
pat = []
a = bitarray()
prev = -1
while len(a) < 1000:
alloc = get_alloc(a)
if prev != alloc:
pat.append(alloc)
prev = alloc
a.append(0)
self.assertEqual(pat, PATTERN)
def test_increase(self):
# make sure sequence of appends will always increase allocated size
a = bitarray()
prev = -1
while len(a) < 100_000:
alloc = get_alloc(a)
self.assertTrue(prev <= alloc)
prev = alloc
a.append(1)
def test_decrease(self):
# ensure that when we start from a large array and delete part, we
# always get a decreasing allocation
a = bitarray(10_000_000)
prev = get_alloc(a)
while a:
del a[-100_000:]
alloc = a.buffer_info()[4]
self.assertTrue(alloc <= prev)
prev = alloc
def test_no_overalloc(self):
# initalizing a bitarray from a list or bitarray does not overallocate
for n in range(1000):
a = bitarray(8 * n * [1])
self.assertEqual(get_alloc(a), n)
b = bitarray(a)
self.assertEqual(get_alloc(b), n)
c = bitarray(8 * n)
self.assertEqual(get_alloc(c), n)
def test_no_overalloc_large(self):
# starting from a large bitarray, make we sure we don't realloc each
# time we extend
a = bitarray(1_000_000) # no overallocation
self.assertEqual(get_alloc(a), 125_000)
a.extend(bitarray(8)) # overallocation happens here
alloc = get_alloc(a)
for _ in range(1000):
a.extend(bitarray(8))
self.assertEqual(get_alloc(a), alloc)
if __name__ == '__main__':
unittest.main()
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