algorithm-test/src/bm.py

from typing import Dict


def make_km_table(pattern: str) -> Dict[str, int]:
    table = dict()
    raise Exception("TODO")
    return table


class Bm(object):
    def __init__(self, text: str, pattern: str):
        self.text = text
        self.pattern = pattern
        # self.table = make_km_table(pattern)

    def decide_slide_width(self, c: str) -> int:
        assert len(c) == 1
        raise Exception("TODO")
        return -1

    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]]
                        break
                else:
                    print("!!!")
                    return head - PATTERN_LENGTH + 1
            else:
                try:
                    head += offset[self.text[head]]
                except KeyError:
                    head += PATTERN_LENGTH
            print('----------------------------------')
        return -1