iterate through a sequence in random order. When all the values have been drawn, if forever=1, the drawing is done again. # noqa: E501 If renewkeys=0, the draw will be in the same order, guaranteeing that the same # noqa: E501 number will be drawn in not less than the number o
| 41 | |
| 42 | |
| 43 | class RandomEnumeration: |
| 44 | """iterate through a sequence in random order. |
| 45 | When all the values have been drawn, if forever=1, the drawing is done again. # noqa: E501 |
| 46 | If renewkeys=0, the draw will be in the same order, guaranteeing that the same # noqa: E501 |
| 47 | number will be drawn in not less than the number of integers of the sequence""" # noqa: E501 |
| 48 | |
| 49 | def __init__(self, inf, sup, seed=None, forever=1, renewkeys=0): |
| 50 | # type: (int, int, Optional[int], int, int) -> None |
| 51 | self.forever = forever |
| 52 | self.renewkeys = renewkeys |
| 53 | self.inf = inf |
| 54 | self.rnd = random.Random(seed) |
| 55 | self.sbox_size = 256 |
| 56 | |
| 57 | self.top = sup - inf + 1 |
| 58 | |
| 59 | n = 0 |
| 60 | while (1 << n) < self.top: |
| 61 | n += 1 |
| 62 | self.n = n |
| 63 | |
| 64 | self.fs = min(3, (n + 1) // 2) |
| 65 | self.fsmask = 2**self.fs - 1 |
| 66 | self.rounds = max(self.n, 3) |
| 67 | self.turns = 0 |
| 68 | self.i = 0 |
| 69 | |
| 70 | def __iter__(self): |
| 71 | # type: () -> RandomEnumeration |
| 72 | return self |
| 73 | |
| 74 | def next(self): |
| 75 | # type: () -> int |
| 76 | while True: |
| 77 | if self.turns == 0 or (self.i == 0 and self.renewkeys): |
| 78 | self.cnt_key = self.rnd.randint(0, 2**self.n - 1) |
| 79 | self.sbox = [self.rnd.randint(0, self.fsmask) |
| 80 | for _ in range(self.sbox_size)] |
| 81 | self.turns += 1 |
| 82 | while self.i < 2**self.n: |
| 83 | ct = self.i ^ self.cnt_key |
| 84 | self.i += 1 |
| 85 | for _ in range(self.rounds): # Unbalanced Feistel Network |
| 86 | lsb = ct & self.fsmask |
| 87 | ct >>= self.fs |
| 88 | lsb ^= self.sbox[ct % self.sbox_size] |
| 89 | ct |= lsb << (self.n - self.fs) |
| 90 | |
| 91 | if ct < self.top: |
| 92 | return self.inf + ct |
| 93 | self.i = 0 |
| 94 | if not self.forever: |
| 95 | raise StopIteration |
| 96 | __next__ = next |
| 97 | |
| 98 | |
| 99 | _T = TypeVar('_T') |
no outgoing calls
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