def boyer_moore(t, w, n, m):
BM = suffix.boyer_moore_shift(w, m)
i = 1
while i <= n - m + 1:
j = m
while j > 0 and t[i + j - 1] == w[j]:
j = j - 1
if j == 0:
yield i
i = i + BM[j]
def boyer_moore_bad_shift(t, w, n, m):
BM, LAST = suffix.boyer_moore_shift(w, m), suffix.last_occurrence(w[:-1])
i = 1
while i <= n - m + 1:
j = m
while j > 0 and t[i + j - 1] == w[j]:
j = j - 1
if j == 0:
yield i
bad_character = LAST.get(t[i + j - 1], 0)
i = i + max(BM[j], j - bad_character)
def boyer_moore_galil(t, w, n, m):
BM = suffix.boyer_moore_shift(w, m)
i, memory = 1, 0
while i <= n - m + 1:
j = m
while j > memory and t[i + j - 1] == w[j]:
j = j - 1
if j == memory:
yield i
i, memory = i + BM[0], m - BM[0]
else:
i, memory = i + BM[j], 0
def boyer_moore_apostolico_giancarlo(t, w, n, m):
def Q(i, k):
return w[max(0, i - k) + 1:i] == w[m - min(k, i) + 1:m]
BM = suffix.boyer_moore_shift(w, m)
skip = [0] * (n + 1)
i = 1
while i <= n - m + 1:
j = m
while j > 0:
if Q(j, skip[i + j - 1]) and t[i + j - 1] == w[j]:
j = j - max(1, skip[i + j - 1])
else:
break
if j <= 0:
yield i
j = 1
skip[i + m - 1] = m - j
i = i + BM[j]
def boyer_moore_turbo(t, w, n, m):
BM = suffix.boyer_moore_shift(w, m)
i, memory, shift = 1, 0, 0
while i <= n - m + 1:
j = m
while j > 0 and t[i + j - 1] == w[j]:
if memory != 0 and j == m - shift:
j = j - memory
else:
j = j - 1
if j == 0:
yield i
match = m - j
turbo_shift = memory - match
shift = max(BM[j], turbo_shift)
if shift > BM[j]:
i = i + max(shift, match + 1)
memory = 0
else:
i = i + shift
memory = min(m - shift, match)
def check_boyer_moore_shift(self, t, n, reference): self.assertEqual(suffix.boyer_moore_shift_brute_force(t, n), reference) self.assertEqual(suffix.boyer_moore_shift(t, n), reference)