| ######################## 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 |
