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latin1prober.py
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Thu, Jul 10, 01:51

latin1prober.py
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######################## BEGIN LICENSE BLOCK ########################
# The Original Code is Mozilla Universal charset detector code.
#
# The Initial Developer of the Original Code is
# Netscape Communications Corporation.
# Portions created by the Initial Developer are Copyright (C) 2001
# the Initial Developer. All Rights Reserved.
#
# Contributor(s):
# Mark Pilgrim - port to Python
# Shy Shalom - original C code
#
# 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 .constants import eNotMe
from .compat import wrap_ord
FREQ_CAT_NUM = 4
UDF = 0 # undefined
OTH = 1 # other
ASC = 2 # ascii capital letter
ASS = 3 # ascii small letter
ACV = 4 # accent capital vowel
ACO = 5 # accent capital other
ASV = 6 # accent small vowel
ASO = 7 # accent small other
CLASS_NUM = 8 # total classes
Latin1_CharToClass = (
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 00 - 07
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 08 - 0F
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 10 - 17
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 18 - 1F
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 20 - 27
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 28 - 2F
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 30 - 37
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 38 - 3F
OTH, ASC, ASC, ASC, ASC, ASC, ASC, ASC, # 40 - 47
ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC, # 48 - 4F
ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC, # 50 - 57
ASC, ASC, ASC, OTH, OTH, OTH, OTH, OTH, # 58 - 5F
OTH, ASS, ASS, ASS, ASS, ASS, ASS, ASS, # 60 - 67
ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS, # 68 - 6F
ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS, # 70 - 77
ASS, ASS, ASS, OTH, OTH, OTH, OTH, OTH, # 78 - 7F
OTH, UDF, OTH, ASO, OTH, OTH, OTH, OTH, # 80 - 87
OTH, OTH, ACO, OTH, ACO, UDF, ACO, UDF, # 88 - 8F
UDF, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 90 - 97
OTH, OTH, ASO, OTH, ASO, UDF, ASO, ACO, # 98 - 9F
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # A0 - A7
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # A8 - AF
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # B0 - B7
OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # B8 - BF
ACV, ACV, ACV, ACV, ACV, ACV, ACO, ACO, # C0 - C7
ACV, ACV, ACV, ACV, ACV, ACV, ACV, ACV, # C8 - CF
ACO, ACO, ACV, ACV, ACV, ACV, ACV, OTH, # D0 - D7
ACV, ACV, ACV, ACV, ACV, ACO, ACO, ACO, # D8 - DF
ASV, ASV, ASV, ASV, ASV, ASV, ASO, ASO, # E0 - E7
ASV, ASV, ASV, ASV, ASV, ASV, ASV, ASV, # E8 - EF
ASO, ASO, ASV, ASV, ASV, ASV, ASV, OTH, # F0 - F7
ASV, ASV, ASV, ASV, ASV, ASO, ASO, ASO, # F8 - FF
)
# 0 : illegal
# 1 : very unlikely
# 2 : normal
# 3 : very likely
Latin1ClassModel = (
# UDF OTH ASC ASS ACV ACO ASV ASO
0, 0, 0, 0, 0, 0, 0, 0, # UDF
0, 3, 3, 3, 3, 3, 3, 3, # OTH
0, 3, 3, 3, 3, 3, 3, 3, # ASC
0, 3, 3, 3, 1, 1, 3, 3, # ASS
0, 3, 3, 3, 1, 2, 1, 2, # ACV
0, 3, 3, 3, 3, 3, 3, 3, # ACO
0, 3, 1, 3, 1, 1, 1, 3, # ASV
0, 3, 1, 3, 1, 1, 3, 3, # ASO
)
class Latin1Prober(CharSetProber):
def __init__(self):
CharSetProber.__init__(self)
self.reset()
def reset(self):
self._mLastCharClass = OTH
self._mFreqCounter = [0] * FREQ_CAT_NUM
CharSetProber.reset(self)
def get_charset_name(self):
return "windows-1252"
def feed(self, aBuf):
aBuf = self.filter_with_english_letters(aBuf)
for c in aBuf:
charClass = Latin1_CharToClass[wrap_ord(c)]
freq = Latin1ClassModel[(self._mLastCharClass * CLASS_NUM)
+ charClass]
if freq == 0:
self._mState = eNotMe
break
self._mFreqCounter[freq] += 1
self._mLastCharClass = charClass
return self.get_state()
def get_confidence(self):
if self.get_state() == eNotMe:
return 0.01
total = sum(self._mFreqCounter)
if total < 0.01:
confidence = 0.0
else:
confidence = ((self._mFreqCounter[3] - self._mFreqCounter[1] * 20.0)
/ total)
if confidence < 0.0:
confidence = 0.0
# lower the confidence of latin1 so that other more accurate
# detector can take priority.
confidence = confidence * 0.73
return confidence

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