######################## BEGIN LICENSE BLOCK ######################## # The Original Code is mozilla.org code. # # The Initial Developer of the Original Code is # Netscape Communications Corporation. # Portions created by the Initial Developer are Copyright (C) 1998 # the Initial Developer. All Rights Reserved. # # Contributor(s): # Mark Pilgrim - port to Python # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 2.1 of the License, or (at your option) any later version. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA # 02110-1301 USA ######################### END LICENSE BLOCK ######################### from typing import Union from .charsetprober import CharSetProber from .codingstatemachine import CodingStateMachine from .enums import MachineState, ProbingState from .mbcssm import UTF8_SM_MODEL class UTF8Prober(CharSetProber): ONE_CHAR_PROB = 0.5 def __init__(self) -> None: super().__init__() self.coding_sm = CodingStateMachine(UTF8_SM_MODEL) self._num_mb_chars = 0 self.reset() def reset(self) -> None: super().reset() self.coding_sm.reset() self._num_mb_chars = 0 @property def charset_name(self) -> str: return "utf-8" @property def language(self) -> str: return "" def feed(self, byte_str: Union[bytes, bytearray]) -> ProbingState: for c in byte_str: coding_state = self.coding_sm.next_state(c) if coding_state == MachineState.ERROR: self._state = ProbingState.NOT_ME break if coding_state == MachineState.ITS_ME: self._state = ProbingState.FOUND_IT break if coding_state == MachineState.START: if self.coding_sm.get_current_charlen() >= 2: self._num_mb_chars += 1 if self.state == ProbingState.DETECTING: if self.get_confidence() > self.SHORTCUT_THRESHOLD: self._state = ProbingState.FOUND_IT return self.state def get_confidence(self) -> float: unlike = 0.99 if self._num_mb_chars < 6: unlike *= self.ONE_CHAR_PROB**self._num_mb_chars return 1.0 - unlike return unlike