Source code for chardet.utf8prober

######################## 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 .charsetprober import CharSetProber
from .codingstatemachine import CodingStateMachine
from .enums import MachineState, ProbingState
from .mbcssm import UTF8_SM_MODEL


[docs]class UTF8Prober(CharSetProber): ONE_CHAR_PROB = 0.5 def __init__(self): super().__init__() self.coding_sm = CodingStateMachine(UTF8_SM_MODEL) self._num_mb_chars = None self.reset()
[docs] def reset(self): super().reset() self.coding_sm.reset() self._num_mb_chars = 0
@property def charset_name(self): return "utf-8" @property def language(self): return ""
[docs] def feed(self, byte_str): for c in byte_str: coding_state = self.coding_sm.next_state(c) if coding_state == MachineState.ERROR: self._state = ProbingState.NOT_ME break elif coding_state == MachineState.ITS_ME: self._state = ProbingState.FOUND_IT break elif 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
[docs] def get_confidence(self): unlike = 0.99 if self._num_mb_chars < 6: unlike *= self.ONE_CHAR_PROB ** self._num_mb_chars return 1.0 - unlike else: return unlike