1 ## Copyright 2002 Andrew Loewenstern, All Rights Reserved
6 random = open('/dev/urandom', 'r') # sucks for windoze
9 """20 bit hash, big-endian -> long python integer"""
10 assert len(hstr) == 20
11 return long(hstr.encode('hex'), 16)
14 """long int -> 20-character string"""
20 str = str.decode('hex')
21 return (20 - len(str)) *'\x00' + str
24 """distance between two 160-bit hashes expressed as 20-character strings"""
25 return intify(a) ^ intify(b)
29 """returns a new pseudorandom globally unique ID string"""
31 h.update(random.read(20))
34 def newIDInRange(min, max):
35 return stringify(randRange(min,max))
37 def randRange(min, max):
38 return min + intify(newID()) % (max - min)
44 class NewID(unittest.TestCase):
46 self.assertEqual(len(newID()), 20)
47 def testHundreds(self):
51 class Intify(unittest.TestCase):
52 known = [('\0' * 20, 0),
53 ('\xff' * 20, 2L**160 - 1),
56 for str, value in self.known:
57 self.assertEqual(intify(str), value)
58 def testEndianessOnce(self):
60 while h[-1] == '\xff':
62 k = h[:-1] + chr(ord(h[-1]) + 1)
63 self.assertEqual(intify(k) - intify(h), 1)
64 def testEndianessLots(self):
66 self.testEndianessOnce()
68 class Disantance(unittest.TestCase):
70 (("\0" * 20, "\xff" * 20), 2**160L -1),
71 ((sha("foo").digest(), sha("foo").digest()), 0),
72 ((sha("bar").digest(), sha("bar").digest()), 0)
75 for pair, dist in self.known:
76 self.assertEqual(distance(pair[0], pair[1]), dist)
77 def testCommutitive(self):
79 x, y, z = newID(), newID(), newID()
80 self.assertEqual(distance(x,y) ^ distance(y, z), distance(x, z))
82 class RandRange(unittest.TestCase):
88 self.assertEqual(a <= c < b, 1, "output out of range %d %d %d" % (b, c, a))
91 assert b <= c < a, "output out of range %d %d %d" % (b, c, a)
93 def testOneHundredTimes(self):
99 if __name__ == '__main__':