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Bm: Break out lookup table, and remove prints

master
Nathan Bergey 5 months ago
parent
commit
0f44e93680
  1. 49
      src/bm.py

49
src/bm.py

@ -2,8 +2,10 @@ from typing import Dict
def make_km_table(pattern: str) -> Dict[str, int]:
table = dict()
raise Exception("TODO")
PATTERN_LENGTH = len(pattern)
table = {}
for index_from_left, char in enumerate(pattern[:-1]):
table[char] = PATTERN_LENGTH - index_from_left - 1
return table
@ -11,44 +13,25 @@ class Bm(object):
def __init__(self, text: str, pattern: str):
self.text = text
self.pattern = pattern
# self.table = make_km_table(pattern)
self.table = make_km_table(pattern)
def decide_slide_width(self, c: str) -> int:
assert len(c) == 1
raise Exception("TODO")
return -1
try:
return self.table[c]
except KeyError:
return len(self.pattern)
def search(self) -> int:
PATTERN_LENGTH = len(self.pattern)
TEXT_LENGTH = len(self.text)
END_OF_PATTERN = PATTERN_LENGTH - 1
LAST_CHAR_OF_PATTERN = self.pattern[-1]
offset = {c: PATTERN_LENGTH - i -1 for i, c in enumerate(self.pattern[:-1])}
print(offset)
matches = []
head = END_OF_PATTERN
while head < TEXT_LENGTH:
print(f'{" " * (head - PATTERN_LENGTH + 1)}{self.pattern}')
print(self.text[:head + 1])
print(f'{" " * head}^')
if self.text[head] == LAST_CHAR_OF_PATTERN:
for i, c in enumerate(reversed(self.pattern)):
# print(text[head - i], c)
if self.text[head - i] != c:
head += offset[self.text[head]]
head = PATTERN_LENGTH - 1
while head < len(self.text):
if self.text[head] == self.pattern[-1]:
for index_from_right, char in enumerate(reversed(self.pattern)):
if self.text[head - index_from_right] != char:
head += self.decide_slide_width(self.text[head])
break
else:
print("!!!")
return head - PATTERN_LENGTH + 1
else:
try:
head += offset[self.text[head]]
except KeyError:
head += PATTERN_LENGTH
print('----------------------------------')
head += self.decide_slide_width(self.text[head])
return -1
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