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bitarray.py
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bitarray.py
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from __future__ import annotations
from secrets import token_bytes
import sys
class BitArray:
def __init__(self, init_value=None, length=None):
if isinstance(init_value, int):
if init_value < 0:
raise ValueError('cannot initialize BitArray with negative value')
self._int = init_value
if init_value != 0:
self.length = length or init_value.bit_length()
else:
self.length = length or 1
elif isinstance(init_value, str):
if not init_value:
self._int = 0
else:
try:
self._int = int(init_value[::-1], 2)
except ValueError as ex:
raise ValueError("str for BitArray must contain only '0' and '1'")
self.length = length or len(init_value)
elif isinstance(init_value, (bytes, bytearray)):
self._int = int.from_bytes(init_value, 'little')
self.length = length or len(init_value) * 8
elif isinstance(init_value, BitArray):
self._int = init_value._int
self.length = init_value.length
elif hasattr(init_value, '__iter__'):
self._int = 0
for i, a in enumerate(init_value):
if a:
self._int |= 1 << i
self.length = length or len(init_value)
elif init_value is None:
self._int = 0
self.length = length or 0
else:
raise TypeError(
f'init_value for BitArray must be iterable or int or string '
f'in binary format, not {init_value.__class__.__name__}'
)
if self.length < self._int.bit_length():
self._int &= (1 << self.length) - 1
def __len__(self):
return self.length
def __repr__(self):
if self.length == 0:
return 'BitArray()'
elif self.length <= 70:
bin_value = f'{self._int:0{self.length}b}'[::-1]
return f"BitArray('{bin_value}')"
elif self.length <= 56 * 4:
hex_value = f'{self._int:0{(self.length + 3) // 4}x}'[::-1]
return f"BitArray(0x{hex_value}, length={self.length})"
else:
first_bytes = f'{self._int & (1 << 16) - 1:016b}'[::-1]
last_bytes = f'{(self._int >> (self.length - 16)):016b}'[::-1]
return (f"BitArray('{first_bytes} <...> "
f"{last_bytes}', length={self.length})")
def __add__(self, other):
if not isinstance(other, BitArray):
raise TypeError(
f'unsupported operation + between BitArray and {other.__class__.__name__}'
)
return BitArray(
self._int + (other._int << self.length), self.length + other.length
)
def __and__(self, other):
if isinstance(other, BitArray):
return BitArray(
self._int & other._int,
min(self.length, other.length)
)
elif isinstance(other, int):
return BitArray(
self._int & other,
self.length
)
else:
raise TypeError(
f'unsupported operation & between BitArray and {other.__class__.__name__}'
)
def __bool__(self):
return self.length > 0
def __eq__(self, other):
if isinstance(other, BitArray):
return self.length == other.length and self._int == other._int
else:
return False
def __int__(self):
return self._int
def __invert__(self):
invert_value = ~self._int & (1 << self.length) - 1
return BitArray(invert_value, self.length)
def __iter__(self):
return map(int, self.binstr)
def __or__(self, other):
if isinstance(other, BitArray):
return BitArray(
self._int | other._int,
max(self.length, other.length)
)
elif isinstance(other, int):
return BitArray(
self._int | other,
self.length
)
else:
raise TypeError(
f'unsupported operation | between BitArray and {other.__class__.__name__}'
)
def __xor__(self, other):
if isinstance(other, BitArray):
return BitArray(
self._int ^ other._int,
max(self.length, other.length)
)
elif isinstance(other, int):
return BitArray(
self._int ^ other,
self.length
)
else:
raise TypeError(
f'unsupported operation ^ between BitArray and {other.__class__.__name__}'
)
def __getitem__(self, index):
if isinstance(index, int):
if index < 0:
index += self.length
return self._int >> index & 1
elif isinstance(index, slice):
start, stop, step = self._slice_check(index)
if step == 1:
return BitArray(
self._int >> start & ((1 << (stop - start)) - 1),
length=(stop - start)
)
else:
res = 0
if step > 0:
for i in range(start, stop, step):
res |= (self._int >> i & 1) << (i - start) // step
else:
for i in reversed(range(start, stop, -step)):
res |= (self._int >> i & 1) << (stop - i - 1) // -step
return BitArray(res, abs((stop - start) // step))
else:
raise TypeError(
f'BitArray indices must be integers or slices, not {index.__class__.__name__}'
)
def __setitem__(self, index, item):
if isinstance(index, int):
if item:
self._int |= 1 << index
else:
self._int -= (self._int >> index & 1) << index
elif isinstance(index, slice):
start, stop, step = self._slice_check(index)
if step == 1:
result = self[:start] + BitArray(item) + self[stop:]
self._int = result._int
self.length = result.length
else:
raise UserWarning('only slices with step 1 implemented')
else:
raise TypeError(
f'BitArray indices must be integers or slices, not {index.__class__.__name__}'
)
def _slice_check(self, sl):
start = sl.start or 0
stop = sl.stop or self.length
step = sl.step or 1
if not (isinstance(start, int) and isinstance(stop, int) and isinstance(step, int)):
raise TypeError('slice indices must be integers or None')
if step == 0:
raise ValueError('slice step cannot be zero')
if start < 0:
start += self.length
if stop < 0:
stop += self.length
return start, stop, step
def __sizeof__(self):
size = 56 + sys.getsizeof(self.__dict__)
for k, v in self.__dict__.items():
size += sys.getsizeof(k) + sys.getsizeof(v)
return size
def append(self, item):
self._int |= bool(item) << self.length
self.length += 1
def to_bytes(self, byteorder='little'):
return self._int.to_bytes((self.length + 7) // 8, byteorder)
@classmethod
def from_bytes(cls, byteobject, length=None, byteorder='little'):
if not isinstance(byteobject, (bytes, bytearray)):
raise TypeError(
f'bytes or bytearray object required for method from_bytes, '
f'not {byteobject.__class__.__name__}'
)
_int = int.from_bytes(byteobject, byteorder)
length = length or len(byteobject) * 8
return cls(_int, length)
def to_file(self, filename, byteorder='little'):
with open(filename, 'wb') as file:
file.write(self.to_bytes(byteorder))
@classmethod
def from_file(cls, filename, length=None, byteorder='little'):
with open(filename, 'rb') as file:
return cls.from_bytes(file.read(), length, byteorder)
def set_all(self, value=True):
if value:
self._int = (1 << self.length) - 1
else:
self._int = 0
@classmethod
def encode(cls, code_dict, string):
cls._check_dict(code_dict, string)
temp_str = ''
for c in string:
temp_str += code_dict[c]
return cls(temp_str)
def decode(self, code_dict):
self._check_dict(code_dict)
rev_dict = {v: k for k, v in sorted(code_dict.items(), key=lambda x: x[1])}
max_code_len = max(map(len, rev_dict.keys()))
temp_str = ''
res = ''
for c in self.binstr:
temp_str += c
if temp_str in rev_dict:
res += rev_dict[temp_str]
temp_str = ''
elif len(temp_str) > max_code_len:
raise ValueError(f"cannot resolve code '{temp_str}'")
if len(temp_str) > 0:
raise ValueError(f"cannot resolve code '{temp_str}'")
return res
@staticmethod
def _check_dict(code_dict, string=''):
for sym, code in code_dict.items():
if not isinstance(sym, str):
raise ValueError(f'keys for code_dict must be str not {sym.__class__.__name__}')
if not isinstance(code, str):
raise ValueError(f'codes must be str not {code.__class__.__name__}')
if len(code) == 0:
raise ValueError(f'empty code for symbol {sym}')
try:
int(code, 2)
except ValueError:
raise ValueError(f'non-binary code {code}')
for c in string:
if c not in code_dict:
raise ValueError(f'no code for symbol {c} in code_dict')
codes = sorted(code_dict.items(), key=lambda x: x[1])
for i in range(1, len(codes)):
if codes[i][1].startswith(codes[i - 1][1]):
raise ValueError(
f'code {codes[i][1]} for symbol {codes[i][0]} '
f'starts with code {codes[i - 1][1]} for symbol {codes[i - 1][0]}'
)
@classmethod
def random(cls, length):
val = int.from_bytes(token_bytes((length + 7) // 8), 'little')
return cls(val, length)
def count(self, value=1):
value = '1' if value else '0'
return self.binstr.count(value)
@staticmethod
def encrypt(msg: str):
bin_msg = BitArray.from_bytes(msg.encode('utf-8'))
token = BitArray.random(len(bin_msg))
secret_msg = bin_msg ^ token
return secret_msg, token
def decrypt(self, key: BitArray):
temp = self ^ key
msg_bytes = temp.to_bytes()
return msg_bytes.decode('utf-8')
def to_list(self):
return list(map(int, self.binstr))
@property
def binstr(self):
res = bin(self._int)[:1:-1]
res += '0' * (len(self) - len(res))
return res
@property
def int_value(self):
return self._int