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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 .enums import ProbingState 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): super(Latin1Prober, self).__init__() self._last_char_class = None self._freq_counter = None self.reset() def reset(self): self._last_char_class = OTH self._freq_counter = [0] * FREQ_CAT_NUM CharSetProber.reset(self) @property def charset_name(self): return "ISO-8859-1" @property def language(self): return "" def feed(self, byte_str): byte_str = self.filter_with_english_letters(byte_str) for c in byte_str: char_class = Latin1_CharToClass[c] freq = Latin1ClassModel[(self._last_char_class * CLASS_NUM) + char_class] if freq == 0: self._state = ProbingState.NOT_ME break self._freq_counter[freq] += 1 self._last_char_class = char_class return self.state def get_confidence(self): if self.state == ProbingState.NOT_ME: return 0.01 total = sum(self._freq_counter) if total < 0.01: confidence = 0.0 else: confidence = ((self._freq_counter[3] - self._freq_counter[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