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Edit File: universaldetector.py

######################## BEGIN LICENSE BLOCK ######################## # The Original Code is Mozilla Universal charset detector code. # # The Initial Developer of the Original Code is # Netscape Communications Corporation. # Portions created by the Initial Developer are Copyright (C) 2001 # the Initial Developer. All Rights Reserved. # # Contributor(s): # Mark Pilgrim - port to Python # Shy Shalom - original C code # # 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 . import constants import sys import codecs from .latin1prober import Latin1Prober # windows-1252 from .mbcsgroupprober import MBCSGroupProber # multi-byte character sets from .sbcsgroupprober import SBCSGroupProber # single-byte character sets from .escprober import EscCharSetProber # ISO-2122, etc. import re MINIMUM_THRESHOLD = 0.20 ePureAscii = 0 eEscAscii = 1 eHighbyte = 2 class UniversalDetector: def __init__(self): self._highBitDetector = re.compile(b'[\x80-\xFF]') self._escDetector = re.compile(b'(\033|~{)') self._mEscCharSetProber = None self._mCharSetProbers = [] self.reset() def reset(self): self.result = {'encoding': None, 'confidence': 0.0} self.done = False self._mStart = True self._mGotData = False self._mInputState = ePureAscii self._mLastChar = b'' if self._mEscCharSetProber: self._mEscCharSetProber.reset() for prober in self._mCharSetProbers: prober.reset() def feed(self, aBuf): if self.done: return aLen = len(aBuf) if not aLen: return if not self._mGotData: # If the data starts with BOM, we know it is UTF if aBuf[:3] == codecs.BOM: # EF BB BF UTF-8 with BOM self.result = {'encoding': "UTF-8", 'confidence': 1.0} elif aBuf[:4] == codecs.BOM_UTF32_LE: # FF FE 00 00 UTF-32, little-endian BOM self.result = {'encoding': "UTF-32LE", 'confidence': 1.0} elif aBuf[:4] == codecs.BOM_UTF32_BE: # 00 00 FE FF UTF-32, big-endian BOM self.result = {'encoding': "UTF-32BE", 'confidence': 1.0} elif aBuf[:4] == b'\xFE\xFF\x00\x00': # FE FF 00 00 UCS-4, unusual octet order BOM (3412) self.result = { 'encoding': "X-ISO-10646-UCS-4-3412", 'confidence': 1.0 } elif aBuf[:4] == b'\x00\x00\xFF\xFE': # 00 00 FF FE UCS-4, unusual octet order BOM (2143) self.result = { 'encoding': "X-ISO-10646-UCS-4-2143", 'confidence': 1.0 } elif aBuf[:2] == codecs.BOM_LE: # FF FE UTF-16, little endian BOM self.result = {'encoding': "UTF-16LE", 'confidence': 1.0} elif aBuf[:2] == codecs.BOM_BE: # FE FF UTF-16, big endian BOM self.result = {'encoding': "UTF-16BE", 'confidence': 1.0} self._mGotData = True if self.result['encoding'] and (self.result['confidence'] > 0.0): self.done = True return if self._mInputState == ePureAscii: if self._highBitDetector.search(aBuf): self._mInputState = eHighbyte elif ((self._mInputState == ePureAscii) and self._escDetector.search(self._mLastChar + aBuf)): self._mInputState = eEscAscii self._mLastChar = aBuf[-1:] if self._mInputState == eEscAscii: if not self._mEscCharSetProber: self._mEscCharSetProber = EscCharSetProber() if self._mEscCharSetProber.feed(aBuf) == constants.eFoundIt: self.result = {'encoding': self._mEscCharSetProber.get_charset_name(), 'confidence': self._mEscCharSetProber.get_confidence()} self.done = True elif self._mInputState == eHighbyte: if not self._mCharSetProbers: self._mCharSetProbers = [MBCSGroupProber(), SBCSGroupProber(), Latin1Prober()] for prober in self._mCharSetProbers: if prober.feed(aBuf) == constants.eFoundIt: self.result = {'encoding': prober.get_charset_name(), 'confidence': prober.get_confidence()} self.done = True break def close(self): if self.done: return if not self._mGotData: if constants._debug: sys.stderr.write('no data received!\n') return self.done = True if self._mInputState == ePureAscii: self.result = {'encoding': 'ascii', 'confidence': 1.0} return self.result if self._mInputState == eHighbyte: proberConfidence = None maxProberConfidence = 0.0 maxProber = None for prober in self._mCharSetProbers: if not prober: continue proberConfidence = prober.get_confidence() if proberConfidence > maxProberConfidence: maxProberConfidence = proberConfidence maxProber = prober if maxProber and (maxProberConfidence > MINIMUM_THRESHOLD): self.result = {'encoding': maxProber.get_charset_name(), 'confidence': maxProber.get_confidence()} return self.result if constants._debug: sys.stderr.write('no probers hit minimum threshhold\n') for prober in self._mCharSetProbers[0].mProbers: if not prober: continue sys.stderr.write('%s confidence = %s\n' % (prober.get_charset_name(), prober.get_confidence()))