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md.py
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md.py
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from functools import lru_cache
from typing import Optional, List
from charset_normalizer.constant import UNICODE_SECONDARY_RANGE_KEYWORD
from charset_normalizer.utils import is_punctuation, is_symbol, unicode_range, is_accentuated, is_latin, \
remove_accent, is_separator, is_cjk, is_case_variable, is_hangul, is_katakana, is_hiragana, is_ascii, is_thai
class MessDetectorPlugin:
"""
Base abstract class used for mess detection plugins.
All detectors MUST extend and implement given methods.
"""
def eligible(self, character: str) -> bool:
"""
Determine if given character should be fed in.
"""
raise NotImplementedError # pragma: nocover
def feed(self, character: str) -> None:
"""
The main routine to be executed upon character.
Insert the logic in witch the text would be considered chaotic.
"""
raise NotImplementedError # pragma: nocover
def reset(self) -> None:
"""
Permit to reset the plugin to the initial state.
"""
raise NotImplementedError # pragma: nocover
@property
def ratio(self) -> float:
"""
Compute the chaos ratio based on what your feed() has seen.
Must NOT be lower than 0.; No restriction gt 0.
"""
raise NotImplementedError # pragma: nocover
class TooManySymbolOrPunctuationPlugin(MessDetectorPlugin):
def __init__(self):
self._punctuation_count = 0 # type: int
self._symbol_count = 0 # type: int
self._character_count = 0 # type: int
self._last_printable_char = None # type: Optional[str]
self._frenzy_symbol_in_word = False # type: bool
def eligible(self, character: str) -> bool:
return character.isprintable()
def feed(self, character: str) -> None:
self._character_count += 1
if character != self._last_printable_char and character not in ["<", ">", "=", ":", "/", "&", ";", "{", "}", "[", "]", ",", "|", '"']:
if is_punctuation(character):
self._punctuation_count += 1
elif character.isdigit() is False and is_symbol(character):
self._symbol_count += 2
self._last_printable_char = character
def reset(self) -> None:
self._punctuation_count = 0
self._character_count = 0
self._symbol_count = 0
@property
def ratio(self) -> float:
if self._character_count == 0:
return 0.
ratio_of_punctuation = (self._punctuation_count + self._symbol_count) / self._character_count # type: float
return ratio_of_punctuation if ratio_of_punctuation >= 0.3 else 0.
class TooManyAccentuatedPlugin(MessDetectorPlugin):
def __init__(self):
self._character_count = 0 # type: int
self._accentuated_count = 0 # type: int
def eligible(self, character: str) -> bool:
return character.isalpha()
def feed(self, character: str) -> None:
self._character_count += 1
if is_accentuated(character):
self._accentuated_count += 1
def reset(self) -> None:
self._character_count = 0
self._accentuated_count = 0
@property
def ratio(self) -> float:
if self._character_count == 0:
return 0.
ratio_of_accentuation = self._accentuated_count / self._character_count # type: float
return ratio_of_accentuation if ratio_of_accentuation >= 0.35 else 0.
class UnprintablePlugin(MessDetectorPlugin):
def __init__(self):
self._unprintable_count = 0 # type: int
self._character_count = 0 # type: int
def eligible(self, character: str) -> bool:
return True
def feed(self, character: str) -> None:
if character not in {'\n', '\t', '\r', '\v'} and character.isprintable() is False:
self._unprintable_count += 1
self._character_count += 1
def reset(self) -> None:
self._unprintable_count = 0
@property
def ratio(self) -> float:
if self._character_count == 0:
return 0.
return (self._unprintable_count * 8) / self._character_count
class SuspiciousDuplicateAccentPlugin(MessDetectorPlugin):
def __init__(self):
self._successive_count = 0 # type: int
self._character_count = 0 # type: int
self._last_latin_character = None # type: Optional[str]
def eligible(self, character: str) -> bool:
return character.isalpha() and is_latin(character)
def feed(self, character: str) -> None:
self._character_count += 1
if self._last_latin_character is not None:
if is_accentuated(character) and is_accentuated(self._last_latin_character):
if character.isupper() and self._last_latin_character.isupper():
self._successive_count += 1
# Worse if its the same char duplicated with different accent.
if remove_accent(character) == remove_accent(self._last_latin_character):
self._successive_count += 1
self._last_latin_character = character
def reset(self) -> None:
self._successive_count = 0
self._character_count = 0
self._last_latin_character = None
@property
def ratio(self) -> float:
if self._character_count == 0:
return 0.
return (self._successive_count * 2) / self._character_count
class SuspiciousRange(MessDetectorPlugin):
def __init__(self):
self._suspicious_successive_range_count = 0 # type: int
self._character_count = 0 # type: int
self._last_printable_seen = None # type: Optional[str]
def eligible(self, character: str) -> bool:
return character.isprintable()
def feed(self, character: str) -> None:
self._character_count += 1
if character.isspace() or is_punctuation(character):
self._last_printable_seen = None
return
if self._last_printable_seen is None:
self._last_printable_seen = character
return
unicode_range_a = unicode_range(self._last_printable_seen) # type: Optional[str]
unicode_range_b = unicode_range(character) # type: Optional[str]
if is_suspiciously_successive_range(unicode_range_a, unicode_range_b):
self._suspicious_successive_range_count += 1
self._last_printable_seen = character
def reset(self) -> None:
self._character_count = 0
self._suspicious_successive_range_count = 0
self._last_printable_seen = None
@property
def ratio(self) -> float:
if self._character_count == 0:
return 0.
ratio_of_suspicious_range_usage = (self._suspicious_successive_range_count * 2) / self._character_count # type: float
if ratio_of_suspicious_range_usage < 0.1:
return 0.
return ratio_of_suspicious_range_usage
class SuperWeirdWordPlugin(MessDetectorPlugin):
def __init__(self):
self._word_count = 0 # type: int
self._bad_word_count = 0 # type: int
self._is_current_word_bad = False # type: bool
self._foreign_long_watch = False # type: bool
self._character_count = 0 # type: int
self._bad_character_count = 0 # type: int
self._buffer = "" # type: str
self._buffer_accent_count = 0 # type: int
def eligible(self, character: str) -> bool:
return True
def feed(self, character: str) -> None:
if character.isalpha():
self._buffer = "".join([self._buffer, character])
if is_accentuated(character):
self._buffer_accent_count += 1
if self._foreign_long_watch is False and is_latin(character) is False and is_cjk(character) is False and is_hangul(character) is False and is_katakana(character) is False and is_hiragana(character) is False and is_thai(character) is False:
self._foreign_long_watch = True
return
if not self._buffer:
return
if (character.isspace() or is_punctuation(character) or is_separator(character)) and self._buffer:
self._word_count += 1
buffer_length = len(self._buffer) # type: int
self._character_count += buffer_length
if buffer_length >= 4 and self._buffer_accent_count / buffer_length >= 0.3:
self._is_current_word_bad = True
if buffer_length >= 24 and self._foreign_long_watch:
self._is_current_word_bad = True
if self._is_current_word_bad:
self._bad_word_count += 1
self._bad_character_count += len(self._buffer)
self._is_current_word_bad = False
self._foreign_long_watch = False
self._buffer = ""
self._buffer_accent_count = 0
elif character not in {"<", ">", "-", "="} and character.isdigit() is False and is_symbol(character):
self._is_current_word_bad = True
self._buffer += character
def reset(self) -> None:
self._buffer = ""
self._is_current_word_bad = False
self._foreign_long_watch = False
self._bad_word_count = 0
self._word_count = 0
self._character_count = 0
self._bad_character_count = 0
@property
def ratio(self) -> float:
if self._word_count <= 10:
return 0.
return self._bad_character_count / self._character_count
class CjkInvalidStopPlugin(MessDetectorPlugin):
"""
GB(Chinese) based encoding often render the stop incorrectly when the content does not fit and can be easily detected.
Searching for the overuse of '丅' and '丄'.
"""
def __init__(self):
self._wrong_stop_count = 0 # type: int
self._cjk_character_count = 0 # type: int
def eligible(self, character: str) -> bool:
return True
def feed(self, character: str) -> None:
if character in ["丅", "丄"]:
self._wrong_stop_count += 1
return
if is_cjk(character):
self._cjk_character_count += 1
def reset(self) -> None:
self._wrong_stop_count = 0
self._cjk_character_count = 0
@property
def ratio(self) -> float:
if self._cjk_character_count < 16:
return 0.
return self._wrong_stop_count / self._cjk_character_count
class ArchaicUpperLowerPlugin(MessDetectorPlugin):
def __init__(self):
self._buf = False # type: bool
self._character_count_since_last_sep = 0 # type: int
self._successive_upper_lower_count = 0 # type: int
self._successive_upper_lower_count_final = 0 # type: int
self._character_count = 0 # type: int
self._last_alpha_seen = None # type: Optional[str]
self._current_ascii_only = True # type: bool
def eligible(self, character: str) -> bool:
return True
def feed(self, character: str) -> None:
is_concerned = character.isalpha() and is_case_variable(character)
chunk_sep = is_concerned is False
if chunk_sep and self._character_count_since_last_sep > 0:
if self._character_count_since_last_sep <= 64 and character.isdigit() is False and self._current_ascii_only is False:
self._successive_upper_lower_count_final += self._successive_upper_lower_count
self._successive_upper_lower_count = 0
self._character_count_since_last_sep = 0
self._last_alpha_seen = None
self._buf = False
self._character_count += 1
self._current_ascii_only = True
return
if self._current_ascii_only is True and is_ascii(character) is False:
self._current_ascii_only = False
if self._last_alpha_seen is not None:
if (character.isupper() and self._last_alpha_seen.islower()) or (character.islower() and self._last_alpha_seen.isupper()):
if self._buf is True:
self._successive_upper_lower_count += 2
self._buf = False
else:
self._buf = True
else:
self._buf = False
self._character_count += 1
self._character_count_since_last_sep += 1
self._last_alpha_seen = character
def reset(self) -> None:
self._character_count = 0
self._character_count_since_last_sep = 0
self._successive_upper_lower_count = 0
self._successive_upper_lower_count_final = 0
self._last_alpha_seen = None
self._buf = False
self._current_ascii_only = True
@property
def ratio(self) -> float:
if self._character_count == 0:
return 0.
return self._successive_upper_lower_count_final / self._character_count
def is_suspiciously_successive_range(unicode_range_a: Optional[str], unicode_range_b: Optional[str]) -> bool:
"""
Determine if two Unicode range seen next to each other can be considered as suspicious.
"""
if unicode_range_a is None or unicode_range_b is None:
return True
if unicode_range_a == unicode_range_b:
return False
if "Latin" in unicode_range_a and "Latin" in unicode_range_b:
return False
if "Emoticons" in unicode_range_a or "Emoticons" in unicode_range_b:
return False
keywords_range_a, keywords_range_b = unicode_range_a.split(" "), unicode_range_b.split(" ")
for el in keywords_range_a:
if el in UNICODE_SECONDARY_RANGE_KEYWORD:
continue
if el in keywords_range_b:
return False
# Japanese Exception
if unicode_range_a in ['Katakana', 'Hiragana'] and unicode_range_b in ['Katakana', 'Hiragana']:
return False
if unicode_range_a in ['Katakana', 'Hiragana'] or unicode_range_b in ['Katakana', 'Hiragana']:
if "CJK" in unicode_range_a or "CJK" in unicode_range_b:
return False
if "Hangul" in unicode_range_a or "Hangul" in unicode_range_b:
if "CJK" in unicode_range_a or "CJK" in unicode_range_b:
return False
if unicode_range_a == "Basic Latin" or unicode_range_b == "Basic Latin":
return False
# Chinese/Japanese use dedicated range for punctuation and/or separators.
if ('CJK' in unicode_range_a or 'CJK' in unicode_range_b) or (unicode_range_a in ['Katakana', 'Hiragana'] and unicode_range_b in ['Katakana', 'Hiragana']):
if 'Punctuation' in unicode_range_a or 'Punctuation' in unicode_range_b:
return False
if 'Forms' in unicode_range_a or 'Forms' in unicode_range_b:
return False
return True
@lru_cache(maxsize=2048)
def mess_ratio(decoded_sequence: str, maximum_threshold: float = 0.2, debug: bool = False) -> float:
"""
Compute a mess ratio given a decoded bytes sequence. The maximum threshold does stop the computation earlier.
"""
detectors = [] # type: List[MessDetectorPlugin]
for md_class in MessDetectorPlugin.__subclasses__():
detectors.append(
md_class()
)
length = len(decoded_sequence) # type: int
mean_mess_ratio = 0. # type: float
if length < 512:
intermediary_mean_mess_ratio_calc = 32 # type: int
elif length <= 1024:
intermediary_mean_mess_ratio_calc = 64
else:
intermediary_mean_mess_ratio_calc = 128
for character, index in zip(decoded_sequence, range(0, length)):
for detector in detectors:
if detector.eligible(character):
detector.feed(character)
if (index > 0 and index % intermediary_mean_mess_ratio_calc == 0) or index == length-1:
mean_mess_ratio = sum(
[
dt.ratio for dt in detectors
]
)
if mean_mess_ratio >= maximum_threshold:
break
if debug:
for dt in detectors: # pragma: nocover
print(
dt.__class__,
dt.ratio
)
return round(
mean_mess_ratio,
3
)