e67a95f15a
Implemented Rabin-Karp rolling hash class abstraction. After testing muliple algorithms for efficient substring searching in a stream abstracted by a ring buffer, I've dropped the idea of using KMP in favor of implementing my own algorithm based of the Rabin-Karp rolling hash algorithm.
61 lines
1.6 KiB
Python
61 lines
1.6 KiB
Python
import unittest
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from byteb4rb1e_utils.string import RollingHash
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class test_compute_initial_hash(unittest.TestCase):
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"""RollingHash.compute_initial_hash()
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i calculated the hashes by hand, as a basis for this test case. Hopefully
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there's no logical flaw...
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"""
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def test_default(self):
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"""computation of hash"""
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result = RollingHash.compute_initial_hash(
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b'abcdefg',
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base = 31,
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mod = 10**9 + 7
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)
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self.assertEqual(result, 988021244)
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class test___init__(unittest.TestCase):
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"""RollingHash.__init__()
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Make sure the class instance is initialized correctly
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I calculated the hashes by hand, as a basis for this test case. Hopefully
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there's no logical flaw...
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"""
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def test_default(self):
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"""computation of initial hash and highest base factor"""
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instance = RollingHash(b'abcdefg')
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self.assertEqual(instance._hash, 988021244)
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self.assertEqual(instance._hbase_factor, 887503681)
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def test_defaults_override(self):
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"""override of defaults"""
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instance = RollingHash(
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b'abcdefg',
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base = 9,
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mod = 4
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)
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self.assertEqual(instance._mod, 4)
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self.assertEqual(instance._base, 9)
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class test_roll(unittest.TestCase):
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"""RollingHash.roll()"""
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def test_rolling_hash(self):
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base=31
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mod=10**9 + 7
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rh = RollingHash(b"foobar", base=base, mod=mod)
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rolled_hash = rh.roll(ord("f"), ord("n"))
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control_hash = RollingHash.compute_initial_hash(b"oobarn", base, mod)
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self.assertEqual(rolled_hash, control_hash)
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