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1######################## BEGIN LICENSE BLOCK ######################## 

2# The Original Code is Mozilla Universal charset detector code. 

3# 

4# The Initial Developer of the Original Code is 

5# Netscape Communications Corporation. 

6# Portions created by the Initial Developer are Copyright (C) 2001 

7# the Initial Developer. All Rights Reserved. 

8# 

9# Contributor(s): 

10# Mark Pilgrim - port to Python 

11# Shy Shalom - original C code 

12# 

13# This library is free software; you can redistribute it and/or 

14# modify it under the terms of the GNU Lesser General Public 

15# License as published by the Free Software Foundation; either 

16# version 2.1 of the License, or (at your option) any later version. 

17# 

18# This library is distributed in the hope that it will be useful, 

19# but WITHOUT ANY WARRANTY; without even the implied warranty of 

20# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 

21# Lesser General Public License for more details. 

22# 

23# You should have received a copy of the GNU Lesser General Public 

24# License along with this library; if not, write to the Free Software 

25# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 

26# 02110-1301 USA 

27######################### END LICENSE BLOCK ######################### 

28 

29from .charsetprober import CharSetProber 

30from .enums import ProbingState 

31 

32FREQ_CAT_NUM = 4 

33 

34UDF = 0 # undefined 

35OTH = 1 # other 

36ASC = 2 # ascii capital letter 

37ASS = 3 # ascii small letter 

38ACV = 4 # accent capital vowel 

39ACO = 5 # accent capital other 

40ASV = 6 # accent small vowel 

41ASO = 7 # accent small other 

42CLASS_NUM = 8 # total classes 

43 

44Latin1_CharToClass = ( 

45 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 00 - 07 

46 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 08 - 0F 

47 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 10 - 17 

48 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 18 - 1F 

49 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 20 - 27 

50 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 28 - 2F 

51 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 30 - 37 

52 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 38 - 3F 

53 OTH, ASC, ASC, ASC, ASC, ASC, ASC, ASC, # 40 - 47 

54 ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC, # 48 - 4F 

55 ASC, ASC, ASC, ASC, ASC, ASC, ASC, ASC, # 50 - 57 

56 ASC, ASC, ASC, OTH, OTH, OTH, OTH, OTH, # 58 - 5F 

57 OTH, ASS, ASS, ASS, ASS, ASS, ASS, ASS, # 60 - 67 

58 ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS, # 68 - 6F 

59 ASS, ASS, ASS, ASS, ASS, ASS, ASS, ASS, # 70 - 77 

60 ASS, ASS, ASS, OTH, OTH, OTH, OTH, OTH, # 78 - 7F 

61 OTH, UDF, OTH, ASO, OTH, OTH, OTH, OTH, # 80 - 87 

62 OTH, OTH, ACO, OTH, ACO, UDF, ACO, UDF, # 88 - 8F 

63 UDF, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # 90 - 97 

64 OTH, OTH, ASO, OTH, ASO, UDF, ASO, ACO, # 98 - 9F 

65 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # A0 - A7 

66 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # A8 - AF 

67 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # B0 - B7 

68 OTH, OTH, OTH, OTH, OTH, OTH, OTH, OTH, # B8 - BF 

69 ACV, ACV, ACV, ACV, ACV, ACV, ACO, ACO, # C0 - C7 

70 ACV, ACV, ACV, ACV, ACV, ACV, ACV, ACV, # C8 - CF 

71 ACO, ACO, ACV, ACV, ACV, ACV, ACV, OTH, # D0 - D7 

72 ACV, ACV, ACV, ACV, ACV, ACO, ACO, ACO, # D8 - DF 

73 ASV, ASV, ASV, ASV, ASV, ASV, ASO, ASO, # E0 - E7 

74 ASV, ASV, ASV, ASV, ASV, ASV, ASV, ASV, # E8 - EF 

75 ASO, ASO, ASV, ASV, ASV, ASV, ASV, OTH, # F0 - F7 

76 ASV, ASV, ASV, ASV, ASV, ASO, ASO, ASO, # F8 - FF 

77) 

78 

79# 0 : illegal 

80# 1 : very unlikely 

81# 2 : normal 

82# 3 : very likely 

83Latin1ClassModel = ( 

84# UDF OTH ASC ASS ACV ACO ASV ASO 

85 0, 0, 0, 0, 0, 0, 0, 0, # UDF 

86 0, 3, 3, 3, 3, 3, 3, 3, # OTH 

87 0, 3, 3, 3, 3, 3, 3, 3, # ASC 

88 0, 3, 3, 3, 1, 1, 3, 3, # ASS 

89 0, 3, 3, 3, 1, 2, 1, 2, # ACV 

90 0, 3, 3, 3, 3, 3, 3, 3, # ACO 

91 0, 3, 1, 3, 1, 1, 1, 3, # ASV 

92 0, 3, 1, 3, 1, 1, 3, 3, # ASO 

93) 

94 

95 

96class Latin1Prober(CharSetProber): 

97 def __init__(self): 

98 super(Latin1Prober, self).__init__() 

99 self._last_char_class = None 

100 self._freq_counter = None 

101 self.reset() 

102 

103 def reset(self): 

104 self._last_char_class = OTH 

105 self._freq_counter = [0] * FREQ_CAT_NUM 

106 CharSetProber.reset(self) 

107 

108 @property 

109 def charset_name(self): 

110 return "ISO-8859-1" 

111 

112 @property 

113 def language(self): 

114 return "" 

115 

116 def feed(self, byte_str): 

117 byte_str = self.filter_with_english_letters(byte_str) 

118 for c in byte_str: 

119 char_class = Latin1_CharToClass[c] 

120 freq = Latin1ClassModel[(self._last_char_class * CLASS_NUM) 

121 + char_class] 

122 if freq == 0: 

123 self._state = ProbingState.NOT_ME 

124 break 

125 self._freq_counter[freq] += 1 

126 self._last_char_class = char_class 

127 

128 return self.state 

129 

130 def get_confidence(self): 

131 if self.state == ProbingState.NOT_ME: 

132 return 0.01 

133 

134 total = sum(self._freq_counter) 

135 if total < 0.01: 

136 confidence = 0.0 

137 else: 

138 confidence = ((self._freq_counter[3] - self._freq_counter[1] * 20.0) 

139 / total) 

140 if confidence < 0.0: 

141 confidence = 0.0 

142 # lower the confidence of latin1 so that other more accurate 

143 # detector can take priority. 

144 confidence = confidence * 0.73 

145 return confidence