Current File : //usr/lib/python2.7/site-packages/pip/_vendor/chardet/utf8prober.py
######################## 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 .enums import ProbingState, MachineState
from .codingstatemachine import CodingStateMachine
from .mbcssm import UTF8_SM_MODEL
class UTF8Prober(CharSetProber):
ONE_CHAR_PROB = 0.5
def __init__(self):
super(UTF8Prober, self).__init__()
self.coding_sm = CodingStateMachine(UTF8_SM_MODEL)
self._num_mb_chars = None
self.reset()
def reset(self):
super(UTF8Prober, self).reset()
self.coding_sm.reset()
self._num_mb_chars = 0
@property
def charset_name(self):
return "utf-8"
@property
def language(self):
return ""
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
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
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