Source code for chardet.charsetprober

######################## 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 #########################

import logging
import re

from .enums import ProbingState


[docs]class CharSetProber: SHORTCUT_THRESHOLD = 0.95 def __init__(self, lang_filter=None): self._state = None self.lang_filter = lang_filter self.logger = logging.getLogger(__name__)
[docs] def reset(self): self._state = ProbingState.DETECTING
@property def charset_name(self): return None
[docs] def feed(self, buf): pass
@property def state(self): return self._state
[docs] def get_confidence(self): return 0.0
[docs] @staticmethod def filter_high_byte_only(buf): buf = re.sub(b"([\x00-\x7F])+", b" ", buf) return buf
[docs] @staticmethod def filter_international_words(buf): """ We define three types of bytes: alphabet: english alphabets [a-zA-Z] international: international characters [\x80-\xFF] marker: everything else [^a-zA-Z\x80-\xFF] The input buffer can be thought to contain a series of words delimited by markers. This function works to filter all words that contain at least one international character. All contiguous sequences of markers are replaced by a single space ascii character. This filter applies to all scripts which do not use English characters. """ filtered = bytearray() # This regex expression filters out only words that have at-least one # international character. The word may include one marker character at # the end. words = re.findall(b"[a-zA-Z]*[\x80-\xFF]+[a-zA-Z]*[^a-zA-Z\x80-\xFF]?", buf) for word in words: filtered.extend(word[:-1]) # If the last character in the word is a marker, replace it with a # space as markers shouldn't affect our analysis (they are used # similarly across all languages and may thus have similar # frequencies). last_char = word[-1:] if not last_char.isalpha() and last_char < b"\x80": last_char = b" " filtered.extend(last_char) return filtered
[docs] @staticmethod def remove_xml_tags(buf): """ Returns a copy of ``buf`` that retains only the sequences of English alphabet and high byte characters that are not between <> characters. This filter can be applied to all scripts which contain both English characters and extended ASCII characters, but is currently only used by ``Latin1Prober``. """ filtered = bytearray() in_tag = False prev = 0 for curr in range(len(buf)): # Slice here to get bytes instead of an int with Python 3 buf_char = buf[curr : curr + 1] # Check if we're coming out of or entering an XML tag if buf_char == b">": prev = curr + 1 in_tag = False elif buf_char == b"<": if curr > prev and not in_tag: # Keep everything after last non-extended-ASCII, # non-alphabetic character filtered.extend(buf[prev:curr]) # Output a space to delimit stretch we kept filtered.extend(b" ") in_tag = True # If we're not in a tag... if not in_tag: # Keep everything after last non-extended-ASCII, non-alphabetic # character filtered.extend(buf[prev:]) return filtered