######################## 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 #########################

import constants, sys
from constants import eStart, eError, eItsMe
from charsetprober import CharSetProber
from codingstatemachine import CodingStateMachine
from mbcssm import UTF8SMModel

ONE_CHAR_PROB = 0.5

class UTF8Prober(CharSetProber):
def __init__(self):
CharSetProber.__init__(self)
self._mCodingSM = CodingStateMachine(UTF8SMModel)
self.reset()

def reset(self):
CharSetProber.reset(self)
self._mCodingSM.reset()
self._mNumOfMBChar = 0

def get_charset_name(self):
return "utf-8"

def feed(self, aBuf):
for c in aBuf:
codingState = self._mCodingSM.next_state(c)
if codingState == eError:
self._mState = constants.eNotMe
break
elif codingState == eItsMe:
self._mState = constants.eFoundIt
break
elif codingState == eStart:
if self._mCodingSM.get_current_charlen() >= 2:
self._mNumOfMBChar += 1

if self.get_state() == constants.eDetecting:
if self.get_confidence() > constants.SHORTCUT_THRESHOLD:
self._mState = constants.eFoundIt

return self.get_state()

def get_confidence(self):
unlike = 0.99
if self._mNumOfMBChar < 6:
for i in range(0, self._mNumOfMBChar):
unlike = unlike * ONE_CHAR_PROB
return 1.0 - unlike
else:
return unlike