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