polish_encoding.py

trans_table = {
    'A': ('A', 0),   'a': ('a', 0),
    'Ą': ('A', 1),   'ą': ('a', 1),
    'C': ('C', 0),   'c': ('c', 0),
    'Ć': ('C', 1),   'ć': ('c', 1),
    'E': ('E', 0),   'e': ('e', 0),
    'Ę': ('E', 1),   'ę': ('e', 1),
    'L': ('L', 0),   'l': ('l', 0),
    'Ł': ('L', 1),   'ł': ('l', 1),
    'N': ('N', 0),   'n': ('n', 0),
    'Ń': ('N', 1),   'ń': ('n', 1),
    'O': ('O', 0),   'o': ('o', 0),
    'Ó': ('O', 1),   'ó': ('o', 1),
    'S': ('S', 0),   's': ('s', 0),
    'Ś': ('S', 1),   'ś': ('s', 1),
    'Z': ('Z', 0),   'z': ('z', 0),
    'Ź': ('Z', 2),   'ź': ('z', 2),
    'Ż': ('Z', 3),   'ż': ('z', 3),
}
ternary_chars = {'Z', 'z'}



def pol2ascii(text):
    plain = []
    diacritics = []
    for c in text:
        if c in trans_table:
            ascii_char, diacritic = trans_table.get(c, (c, 0))
            diacritics.append(bin(diacritic)[2:][::-1])
        else:
            ascii_char = c
        plain.append(ascii_char)

    return ''.join(plain) + '_' + hex(int(''.join(reversed(diacritics)), 2))[2:]

reverse_trans_table = {
    k: v for v, k in trans_table.items()
}

def ascii2pol(text):
    plain, diacritics = text.rsplit('_', 1)
    diacritics = int(diacritics, base=16)
    res = []

    for c in plain:
        if c in trans_table:
            diacritic = diacritics % 2
            diacritics = diacritics // 2
            if c in ternary_chars and diacritic == 1:
                diacritic = diacritic * 2 + (diacritics % 2)
                diacritics = diacritics // 2
            pol_char = reverse_trans_table.get((c, diacritic), c)
        else:
            pol_char = c
        res.append(pol_char)

    return ''.join(res)


TESTS = '''
Świętosław Milczący
Dzierżykraj Łaźniński
Józef Soćko
jedną rzucających się zachodzących języka męskorzeczowego męskożywotny. słów, które w polszczyźnie standardowej były
'''

for l in TESTS.strip().splitlines():
    plain = pol2ascii(l)
    original = ascii2pol(plain)
    print(original, plain, f'+{(len(plain) / len(original) - 1) * 100:.1f}%')
    print(l)
    assert original == l