관리-도구

편집 파일: chardistribution.py

######################## 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 (EUCTWCharToFreqOrder, EUCTW_TABLE_SIZE, EUCTW_TYPICAL_DISTRIBUTION_RATIO) from .euckrfreq import (EUCKRCharToFreqOrder, EUCKR_TABLE_SIZE, EUCKR_TYPICAL_DISTRIBUTION_RATIO) from .gb2312freq import (GB2312CharToFreqOrder, GB2312_TABLE_SIZE, GB2312_TYPICAL_DISTRIBUTION_RATIO) from .big5freq import (Big5CharToFreqOrder, BIG5_TABLE_SIZE, BIG5_TYPICAL_DISTRIBUTION_RATIO) from .jisfreq import (JISCharToFreqOrder, JIS_TABLE_SIZE, JIS_TYPICAL_DISTRIBUTION_RATIO) from .compat import wrap_ord ENOUGH_DATA_THRESHOLD = 1024 SURE_YES = 0.99 SURE_NO = 0.01 MINIMUM_DATA_THRESHOLD = 3 class CharDistributionAnalysis: def __init__(self): # Mapping table to get frequency order from char order (get from # GetOrder()) self._mCharToFreqOrder = None self._mTableSize = 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._mTypicalDistributionRatio = 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._mDone = False self._mTotalChars = 0 # Total characters encountered # The number of characters whose frequency order is less than 512 self._mFreqChars = 0 def feed(self, aBuf, aCharLen): """feed a character with known length""" if aCharLen == 2: # we only care about 2-bytes character in our distribution analysis order = self.get_order(aBuf) else: order = -1 if order >= 0: self._mTotalChars += 1 # order is valid if order < self._mTableSize: if 512 > self._mCharToFreqOrder[order]: self._mFreqChars += 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._mTotalChars <= 0 or self._mFreqChars <= MINIMUM_DATA_THRESHOLD: return SURE_NO if self._mTotalChars != self._mFreqChars: r = (self._mFreqChars / ((self._mTotalChars - self._mFreqChars) * self._mTypicalDistributionRatio)) if r < SURE_YES: return r # normalize confidence (we don't want to be 100% sure) return 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._mTotalChars > ENOUGH_DATA_THRESHOLD def get_order(self, aBuf): # 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): CharDistributionAnalysis.__init__(self) self._mCharToFreqOrder = EUCTWCharToFreqOrder self._mTableSize = EUCTW_TABLE_SIZE self._mTypicalDistributionRatio = EUCTW_TYPICAL_DISTRIBUTION_RATIO def get_order(self, aBuf): # 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 = wrap_ord(aBuf[0]) if first_char >= 0xC4: return 94 * (first_char - 0xC4) + wrap_ord(aBuf[1]) - 0xA1 else: return -1 class EUCKRDistributionAnalysis(CharDistributionAnalysis): def __init__(self): CharDistributionAnalysis.__init__(self) self._mCharToFreqOrder = EUCKRCharToFreqOrder self._mTableSize = EUCKR_TABLE_SIZE self._mTypicalDistributionRatio = EUCKR_TYPICAL_DISTRIBUTION_RATIO def get_order(self, aBuf): # 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 = wrap_ord(aBuf[0]) if first_char >= 0xB0: return 94 * (first_char - 0xB0) + wrap_ord(aBuf[1]) - 0xA1 else: return -1 class GB2312DistributionAnalysis(CharDistributionAnalysis): def __init__(self): CharDistributionAnalysis.__init__(self) self._mCharToFreqOrder = GB2312CharToFreqOrder self._mTableSize = GB2312_TABLE_SIZE self._mTypicalDistributionRatio = GB2312_TYPICAL_DISTRIBUTION_RATIO def get_order(self, aBuf): # 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 = wrap_ord(aBuf[0]), wrap_ord(aBuf[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): CharDistributionAnalysis.__init__(self) self._mCharToFreqOrder = Big5CharToFreqOrder self._mTableSize = BIG5_TABLE_SIZE self._mTypicalDistributionRatio = BIG5_TYPICAL_DISTRIBUTION_RATIO def get_order(self, aBuf): # 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 = wrap_ord(aBuf[0]), wrap_ord(aBuf[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): CharDistributionAnalysis.__init__(self) self._mCharToFreqOrder = JISCharToFreqOrder self._mTableSize = JIS_TABLE_SIZE self._mTypicalDistributionRatio = JIS_TYPICAL_DISTRIBUTION_RATIO def get_order(self, aBuf): # 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 = wrap_ord(aBuf[0]), wrap_ord(aBuf[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): CharDistributionAnalysis.__init__(self) self._mCharToFreqOrder = JISCharToFreqOrder self._mTableSize = JIS_TABLE_SIZE self._mTypicalDistributionRatio = JIS_TYPICAL_DISTRIBUTION_RATIO def get_order(self, aBuf): # 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 = wrap_ord(aBuf[0]) if char >= 0xA0: return 94 * (char - 0xA1) + wrap_ord(aBuf[1]) - 0xa1 else: return -1