######################## 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 ######################### """ Module containing the UniversalDetector detector class, which is the primary class a user of ``chardet`` should use. :author: Mark Pilgrim (intial port to Python) :author: Shy Shalom (original C code) :author: Dan Blanchard (major refactoring for 3.0) :author: Ian Cordasco """ import codecs import logging import re from .enums import InputState, LanguageFilter, ProbingState from .escprober import EscCharSetProber from .latin1prober import Latin1Prober from .mbcsgroupprober import MBCSGroupProber from .sbcsgroupprober import SBCSGroupProber class UniversalDetector(object): """ The ``UniversalDetector`` class underlies the ``chardet.detect`` function and coordinates all of the different charset probers. To get a ``dict`` containing an encoding and its confidence, you can simply run: .. code:: u = UniversalDetector() u.feed(some_bytes) u.close() detected = u.result """ MINIMUM_THRESHOLD = 0.20 HIGH_BYTE_DETECTOR = re.compile(b'[\x80-\xFF]') ESC_DETECTOR = re.compile(b'(\033|~{)') def __init__(self, lang_filter=LanguageFilter.all): self._esc_charset_prober = None self._charset_probers = [] self.result = None self.done = None self._got_data = None self._input_state = None self._last_char = None self.lang_filter = lang_filter self.logger = logging.getLogger(__name__) self.reset() def reset(self): """ Reset the UniversalDetector and all of its probers back to their initial states. This is called by ``__init__``, so you only need to call this directly in between analyses of different documents. """ self.result = {'encoding': None, 'confidence': 0.0} self.done = False self._got_data = False self._input_state = InputState.pure_ascii self._last_char = b'' if self._esc_charset_prober: self._esc_charset_prober.reset() for prober in self._charset_probers: prober.reset() def feed(self, byte_str): """ Takes a chunk of a document and feeds it through all of the relevant charset probers. After calling ``feed``, you can check the value of the ``done`` attribute to see if you need to continue feeding the ``UniversalDetector`` more data, or if it has made a prediction (in the ``result`` attribute). .. note:: You should always call ``close`` when you're done feeding in your document if ``done`` is not already ``True``. """ if self.done: return if not len(byte_str): return # First check for known BOMs, since these are guaranteed to be correct if not self._got_data: # If the data starts with BOM, we know it is UTF if byte_str.startswith(codecs.BOM_UTF8): # EF BB BF UTF-8 with BOM self.result = {'encoding': "UTF-8-SIG", 'confidence': 1.0} elif byte_str.startswith(codecs.BOM_UTF32_LE): # FF FE 00 00 UTF-32, little-endian BOM self.result = {'encoding': "UTF-32LE", 'confidence': 1.0} elif byte_str.startswith(codecs.BOM_UTF32_BE): # 00 00 FE FF UTF-32, big-endian BOM self.result = {'encoding': "UTF-32BE", 'confidence': 1.0} elif byte_str.startswith(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 byte_str.startswith(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 byte_str.startswith(codecs.BOM_LE): # FF FE UTF-16, little endian BOM self.result = {'encoding': "UTF-16LE", 'confidence': 1.0} elif byte_str.startswith(codecs.BOM_BE): # FE FF UTF-16, big endian BOM self.result = {'encoding': "UTF-16BE", 'confidence': 1.0} self._got_data = True if self.result['encoding'] is not None: self.done = True return # If none of those matched and we've only see ASCII so far, check # for high bytes and escape sequences if self._input_state == InputState.pure_ascii: if self.HIGH_BYTE_DETECTOR.search(byte_str): self._input_state = InputState.high_byte elif self._input_state == InputState.pure_ascii and \ self.ESC_DETECTOR.search(self._last_char + byte_str): self._input_state = InputState.esc_ascii self._last_char = byte_str[-1:] # If we've seen escape sequences, use the EscCharSetProber, which # uses a simple state machine to check for known escape sequences in # HZ and ISO-2022 encodings, since those are the only encodings that # use such sequences. if self._input_state == InputState.esc_ascii: if not self._esc_charset_prober: self._esc_charset_prober = EscCharSetProber(self.lang_filter) if self._esc_charset_prober.feed(byte_str) == ProbingState.found_it: self.result = {'encoding': self._esc_charset_prober.charset_name, 'confidence': self._esc_charset_prober.get_confidence()} self.done = True # If we've seen high bytes (i.e., those with values greater than 127), # we need to do more complicated checks using all our multi-byte and # single-byte probers that are left. The single-byte probers # use character bigram distributions to determine the encoding, whereas # the multi-byte probers use a combination of character unigram and # bigram distributions. elif self._input_state == InputState.high_byte: if not self._charset_probers: self._charset_probers = [MBCSGroupProber(self.lang_filter)] # If we're checking non-CJK encodings, use single-byte prober if self.lang_filter & LanguageFilter.non_cjk: self._charset_probers.append(SBCSGroupProber()) self._charset_probers.append(Latin1Prober()) for prober in self._charset_probers: if prober.feed(byte_str) == ProbingState.found_it: self.result = {'encoding': prober.charset_name, 'confidence': prober.get_confidence()} self.done = True break def close(self): """ Stop analyzing the current document and come up with a final prediction. :returns: The ``result`` attribute if a prediction was made, otherwise ``None``. """ if self.done: return self.result if not self._got_data: self.logger.debug('no data received!') return self.done = True if self._input_state == InputState.pure_ascii: self.result = {'encoding': 'ascii', 'confidence': 1.0} return self.result if self._input_state == InputState.high_byte: proberConfidence = None max_prober_confidence = 0.0 max_prober = None for prober in self._charset_probers: if not prober: continue proberConfidence = prober.get_confidence() if proberConfidence > max_prober_confidence: max_prober_confidence = proberConfidence max_prober = prober if max_prober and (max_prober_confidence > self.MINIMUM_THRESHOLD): self.result = {'encoding': max_prober.charset_name, 'confidence': max_prober.get_confidence()} return self.result if self.logger.getEffectiveLevel() == logging.DEBUG: self.logger.debug('no probers hit minimum threshhold') for prober in self._charset_probers[0].mProbers: if not prober: continue self.logger.debug('%s confidence = %s', prober.charset_name, prober.get_confidence())