|
######################## 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 (initial port to Python) :author: Shy Shalom (original C code) :author: Dan Blanchard (major refactoring for 3.0) :author: Ian Cordasco """
""" 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
"""
'iso-8859-2': 'Windows-1250', 'iso-8859-5': 'Windows-1251', 'iso-8859-6': 'Windows-1256', 'iso-8859-7': 'Windows-1253', 'iso-8859-8': 'Windows-1255', 'iso-8859-9': 'Windows-1254', 'iso-8859-13': 'Windows-1257'}
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._has_win_bytes = None self.reset()
""" 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, 'language': None} self.done = False self._got_data = False self._has_win_bytes = 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()
""" 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
if not isinstance(byte_str, bytearray): byte_str = bytearray(byte_str)
# 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, 'language': ''} elif byte_str.startswith((codecs.BOM_UTF32_LE, codecs.BOM_UTF32_BE)): # FF FE 00 00 UTF-32, little-endian BOM # 00 00 FE FF UTF-32, big-endian BOM self.result = {'encoding': "UTF-32", 'confidence': 1.0, 'language': ''} 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, 'language': ''} 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, 'language': ''} elif byte_str.startswith((codecs.BOM_LE, codecs.BOM_BE)): # FF FE UTF-16, little endian BOM # FE FF UTF-16, big endian BOM self.result = {'encoding': "UTF-16", 'confidence': 1.0, 'language': ''}
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(), 'language': self._esc_charset_prober.language} 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(), 'language': prober.language} self.done = True break if self.WIN_BYTE_DETECTOR.search(byte_str): self._has_win_bytes = True
""" Stop analyzing the current document and come up with a final prediction.
:returns: The ``result`` attribute, a ``dict`` with the keys `encoding`, `confidence`, and `language`. """ # Don't bother with checks if we're already done if self.done: return self.result self.done = True
if not self._got_data: self.logger.debug('no data received!')
# Default to ASCII if it is all we've seen so far elif self._input_state == InputState.PURE_ASCII: self.result = {'encoding': 'ascii', 'confidence': 1.0, 'language': ''}
# If we have seen non-ASCII, return the best that met MINIMUM_THRESHOLD elif self._input_state == InputState.HIGH_BYTE: prober_confidence = None max_prober_confidence = 0.0 max_prober = None for prober in self._charset_probers: if not prober: continue prober_confidence = prober.get_confidence() if prober_confidence > max_prober_confidence: max_prober_confidence = prober_confidence max_prober = prober if max_prober and (max_prober_confidence > self.MINIMUM_THRESHOLD): charset_name = max_prober.charset_name lower_charset_name = max_prober.charset_name.lower() confidence = max_prober.get_confidence() # Use Windows encoding name instead of ISO-8859 if we saw any # extra Windows-specific bytes if lower_charset_name.startswith('iso-8859'): if self._has_win_bytes: charset_name = self.ISO_WIN_MAP.get(lower_charset_name, charset_name) self.result = {'encoding': charset_name, 'confidence': confidence, 'language': max_prober.language}
# Log all prober confidences if none met MINIMUM_THRESHOLD if self.logger.getEffectiveLevel() == logging.DEBUG: if self.result['encoding'] is None: self.logger.debug('no probers hit minimum threshold') for group_prober in self._charset_probers: if not group_prober: continue if isinstance(group_prober, CharSetGroupProber): for prober in group_prober.probers: self.logger.debug('%s %s confidence = %s', prober.charset_name, prober.language, prober.get_confidence()) else: self.logger.debug('%s %s confidence = %s', prober.charset_name, prober.language, prober.get_confidence()) return self.result |