Mercurial Repositories > eric / file comparison
comparison: ThirdParty/CharDet/chardet/sbcharsetprober.py
ThirdParty/CharDet/chardet/sbcharsetprober.py
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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 | |
| 29 import constants, sys | |
| 30 from charsetprober import CharSetProber | |
| 31 | |
| 32 SAMPLE_SIZE = 64 | |
| 33 SB_ENOUGH_REL_THRESHOLD = 1024 | |
| 34 POSITIVE_SHORTCUT_THRESHOLD = 0.95 | |
| 35 NEGATIVE_SHORTCUT_THRESHOLD = 0.05 | |
| 36 SYMBOL_CAT_ORDER = 250 | |
| 37 NUMBER_OF_SEQ_CAT = 4 | |
| 38 POSITIVE_CAT = NUMBER_OF_SEQ_CAT - 1 | |
| 39 #NEGATIVE_CAT = 0 | |
| 40 | |
| 41 class SingleByteCharSetProber(CharSetProber): | |
| 42 def __init__(self, model, reversed=constants.False, nameProber=None): | |
| 43 CharSetProber.__init__(self) | |
| 44 self._mModel = model | |
| 45 self._mReversed = reversed # TRUE if we need to reverse every pair in the model lookup | |
| 46 self._mNameProber = nameProber # Optional auxiliary prober for name decision | |
| 47 self.reset() | |
| 48 | |
| 49 def reset(self): | |
| 50 CharSetProber.reset(self) | |
| 51 self._mLastOrder = 255 # char order of last character | |
| 52 self._mSeqCounters = [0] * NUMBER_OF_SEQ_CAT | |
| 53 self._mTotalSeqs = 0 | |
| 54 self._mTotalChar = 0 | |
| 55 self._mFreqChar = 0 # characters that fall in our sampling range | |
| 56 | |
| 57 def get_charset_name(self): | |
| 58 if self._mNameProber: | |
| 59 return self._mNameProber.get_charset_name() | |
| 60 else: | |
| 61 return self._mModel['charsetName'] | |
| 62 | |
| 63 def feed(self, aBuf): | |
| 64 if not self._mModel['keepEnglishLetter']: | |
| 65 aBuf = self.filter_without_english_letters(aBuf) | |
| 66 aLen = len(aBuf) | |
| 67 if not aLen: | |
| 68 return self.get_state() | |
| 69 for c in aBuf: | |
| 70 order = self._mModel['charToOrderMap'][ord(c)] | |
| 71 if order < SYMBOL_CAT_ORDER: | |
| 72 self._mTotalChar += 1 | |
| 73 if order < SAMPLE_SIZE: | |
| 74 self._mFreqChar += 1 | |
| 75 if self._mLastOrder < SAMPLE_SIZE: | |
| 76 self._mTotalSeqs += 1 | |
| 77 if not self._mReversed: | |
| 78 self._mSeqCounters[self._mModel['precedenceMatrix'][(self._mLastOrder * SAMPLE_SIZE) + order]] += 1 | |
| 79 else: # reverse the order of the letters in the lookup | |
| 80 self._mSeqCounters[self._mModel['precedenceMatrix'][(order * SAMPLE_SIZE) + self._mLastOrder]] += 1 | |
| 81 self._mLastOrder = order | |
| 82 | |
| 83 if self.get_state() == constants.eDetecting: | |
| 84 if self._mTotalSeqs > SB_ENOUGH_REL_THRESHOLD: | |
| 85 cf = self.get_confidence() | |
| 86 if cf > POSITIVE_SHORTCUT_THRESHOLD: | |
| 87 if constants._debug: | |
| 88 sys.stderr.write('%s confidence = %s, we have a winner\n' % (self._mModel['charsetName'], cf)) | |
| 89 self._mState = constants.eFoundIt | |
| 90 elif cf < NEGATIVE_SHORTCUT_THRESHOLD: | |
| 91 if constants._debug: | |
| 92 sys.stderr.write('%s confidence = %s, below negative shortcut threshhold %s\n' % (self._mModel['charsetName'], cf, NEGATIVE_SHORTCUT_THRESHOLD)) | |
| 93 self._mState = constants.eNotMe | |
| 94 | |
| 95 return self.get_state() | |
| 96 | |
| 97 def get_confidence(self): | |
| 98 r = 0.01 | |
| 99 if self._mTotalSeqs > 0: | |
| 100 # print self._mSeqCounters[POSITIVE_CAT], self._mTotalSeqs, self._mModel['mTypicalPositiveRatio'] | |
| 101 r = (1.0 * self._mSeqCounters[POSITIVE_CAT]) / self._mTotalSeqs / self._mModel['mTypicalPositiveRatio'] | |
| 102 # print r, self._mFreqChar, self._mTotalChar | |
| 103 r = r * self._mFreqChar / self._mTotalChar | |
| 104 if r >= 1.0: | |
| 105 r = 0.99 | |
| 106 return r |
