Coverage for chardet/chardistribution.py: 29%

# Coverage for chardet/chardistribution.py : 29%

## 117 statements 34 run 83 missing 0 excluded

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 | ######################## BEGIN LICENSE BLOCK ######################## # The Original Code is Mozilla Communicator client 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 .euctwfreq import (EUCTW_CHAR_TO_FREQ_ORDER, EUCTW_TABLE_SIZE, EUCTW_TYPICAL_DISTRIBUTION_RATIO) from .euckrfreq import (EUCKR_CHAR_TO_FREQ_ORDER, EUCKR_TABLE_SIZE, EUCKR_TYPICAL_DISTRIBUTION_RATIO) from .gb2312freq import (GB2312_CHAR_TO_FREQ_ORDER, GB2312_TABLE_SIZE, GB2312_TYPICAL_DISTRIBUTION_RATIO) from .big5freq import (BIG5_CHAR_TO_FREQ_ORDER, BIG5_TABLE_SIZE, BIG5_TYPICAL_DISTRIBUTION_RATIO) from .jisfreq import (JIS_CHAR_TO_FREQ_ORDER, JIS_TABLE_SIZE, JIS_TYPICAL_DISTRIBUTION_RATIO) class CharDistributionAnalysis(object): ENOUGH_DATA_THRESHOLD = 1024 SURE_YES = 0.99 SURE_NO = 0.01 MINIMUM_DATA_THRESHOLD = 3 def __init__(self): # Mapping table to get frequency order from char order (get from # GetOrder()) self._char_to_freq_order = None self._table_size = None # Size of above table # This is a constant value which varies from language to language, # used in calculating confidence. See # http://www.mozilla.org/projects/intl/UniversalCharsetDetection.html # for further detail. self.typical_distribution_ratio = None self._done = None self._total_chars = None self._freq_chars = None self.reset() def reset(self): """reset analyser, clear any state""" # If this flag is set to True, detection is done and conclusion has # been made self._done = False self._total_chars = 0 # Total characters encountered # The number of characters whose frequency order is less than 512 self._freq_chars = 0 def feed(self, char, char_len): """feed a character with known length""" if char_len == 2: # we only care about 2-bytes character in our distribution analysis order = self.get_order(char) else: order = -1 if order >= 0: self._total_chars += 1 # order is valid if order < self._table_size: if 512 > self._char_to_freq_order[order]: self._freq_chars += 1 def get_confidence(self): """return confidence based on existing data""" # if we didn't receive any character in our consideration range, # return negative answer if self._total_chars <= 0 or self._freq_chars <= self.MINIMUM_DATA_THRESHOLD: return self.SURE_NO if self._total_chars != self._freq_chars: r = (self._freq_chars / ((self._total_chars - self._freq_chars) * self.typical_distribution_ratio)) if r < self.SURE_YES: return r # normalize confidence (we don't want to be 100% sure) return self.SURE_YES def got_enough_data(self): # It is not necessary to receive all data to draw conclusion. # For charset detection, certain amount of data is enough return self._total_chars > self.ENOUGH_DATA_THRESHOLD def get_order(self, byte_str): # We do not handle characters based on the original encoding string, # but convert this encoding string to a number, here called order. # This allows multiple encodings of a language to share one frequency # table. return -1 class EUCTWDistributionAnalysis(CharDistributionAnalysis): def __init__(self): super(EUCTWDistributionAnalysis, self).__init__() self._char_to_freq_order = EUCTW_CHAR_TO_FREQ_ORDER self._table_size = EUCTW_TABLE_SIZE self.typical_distribution_ratio = EUCTW_TYPICAL_DISTRIBUTION_RATIO def get_order(self, byte_str): # for euc-TW encoding, we are interested # first byte range: 0xc4 -- 0xfe # second byte range: 0xa1 -- 0xfe # no validation needed here. State machine has done that first_char = byte_str[0] if first_char >= 0xC4: return 94 * (first_char - 0xC4) + byte_str[1] - 0xA1 else: return -1 class EUCKRDistributionAnalysis(CharDistributionAnalysis): def __init__(self): super(EUCKRDistributionAnalysis, self).__init__() self._char_to_freq_order = EUCKR_CHAR_TO_FREQ_ORDER self._table_size = EUCKR_TABLE_SIZE self.typical_distribution_ratio = EUCKR_TYPICAL_DISTRIBUTION_RATIO def get_order(self, byte_str): # for euc-KR encoding, we are interested # first byte range: 0xb0 -- 0xfe # second byte range: 0xa1 -- 0xfe # no validation needed here. State machine has done that first_char = byte_str[0] if first_char >= 0xB0: return 94 * (first_char - 0xB0) + byte_str[1] - 0xA1 else: return -1 class GB2312DistributionAnalysis(CharDistributionAnalysis): def __init__(self): super(GB2312DistributionAnalysis, self).__init__() self._char_to_freq_order = GB2312_CHAR_TO_FREQ_ORDER self._table_size = GB2312_TABLE_SIZE self.typical_distribution_ratio = GB2312_TYPICAL_DISTRIBUTION_RATIO def get_order(self, byte_str): # for GB2312 encoding, we are interested # first byte range: 0xb0 -- 0xfe # second byte range: 0xa1 -- 0xfe # no validation needed here. State machine has done that first_char, second_char = byte_str[0], byte_str[1] if (first_char >= 0xB0) and (second_char >= 0xA1): return 94 * (first_char - 0xB0) + second_char - 0xA1 else: return -1 class Big5DistributionAnalysis(CharDistributionAnalysis): def __init__(self): super(Big5DistributionAnalysis, self).__init__() self._char_to_freq_order = BIG5_CHAR_TO_FREQ_ORDER self._table_size = BIG5_TABLE_SIZE self.typical_distribution_ratio = BIG5_TYPICAL_DISTRIBUTION_RATIO def get_order(self, byte_str): # for big5 encoding, we are interested # first byte range: 0xa4 -- 0xfe # second byte range: 0x40 -- 0x7e , 0xa1 -- 0xfe # no validation needed here. State machine has done that first_char, second_char = byte_str[0], byte_str[1] if first_char >= 0xA4: if second_char >= 0xA1: return 157 * (first_char - 0xA4) + second_char - 0xA1 + 63 else: return 157 * (first_char - 0xA4) + second_char - 0x40 else: return -1 class SJISDistributionAnalysis(CharDistributionAnalysis): def __init__(self): super(SJISDistributionAnalysis, self).__init__() self._char_to_freq_order = JIS_CHAR_TO_FREQ_ORDER self._table_size = JIS_TABLE_SIZE self.typical_distribution_ratio = JIS_TYPICAL_DISTRIBUTION_RATIO def get_order(self, byte_str): # for sjis encoding, we are interested # first byte range: 0x81 -- 0x9f , 0xe0 -- 0xfe # second byte range: 0x40 -- 0x7e, 0x81 -- oxfe # no validation needed here. State machine has done that first_char, second_char = byte_str[0], byte_str[1] if (first_char >= 0x81) and (first_char <= 0x9F): order = 188 * (first_char - 0x81) elif (first_char >= 0xE0) and (first_char <= 0xEF): order = 188 * (first_char - 0xE0 + 31) else: return -1 order = order + second_char - 0x40 if second_char > 0x7F: order = -1 return order class EUCJPDistributionAnalysis(CharDistributionAnalysis): def __init__(self): super(EUCJPDistributionAnalysis, self).__init__() self._char_to_freq_order = JIS_CHAR_TO_FREQ_ORDER self._table_size = JIS_TABLE_SIZE self.typical_distribution_ratio = JIS_TYPICAL_DISTRIBUTION_RATIO def get_order(self, byte_str): # for euc-JP encoding, we are interested # first byte range: 0xa0 -- 0xfe # second byte range: 0xa1 -- 0xfe # no validation needed here. State machine has done that char = byte_str[0] if char >= 0xA0: return 94 * (char - 0xA1) + byte_str[1] - 0xa1 else: return -1