Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/chardet/charsetprober.py: 95%

1######################## BEGIN LICENSE BLOCK ######################## 

2# The Original Code is Mozilla Universal charset detector code. 

3# 

4# The Initial Developer of the Original Code is 

5# Netscape Communications Corporation. 

6# Portions created by the Initial Developer are Copyright (C) 2001 

7# the Initial Developer. All Rights Reserved. 

8# 

9# Contributor(s): 

10# Mark Pilgrim - port to Python 

11# Shy Shalom - original C code 

12# 

13# This library is free software; you can redistribute it and/or 

14# modify it under the terms of the GNU Lesser General Public 

15# License as published by the Free Software Foundation; either 

16# version 2.1 of the License, or (at your option) any later version. 

17# 

18# This library is distributed in the hope that it will be useful, 

19# but WITHOUT ANY WARRANTY; without even the implied warranty of 

20# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 

21# Lesser General Public License for more details. 

22# 

23# You should have received a copy of the GNU Lesser General Public 

24# License along with this library; if not, write to the Free Software 

25# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 

26# 02110-1301 USA 

27######################### END LICENSE BLOCK ######################### 

28 

29import logging 

30import re 

31from typing import Optional, Union 

32 

33from .enums import LanguageFilter, ProbingState 

34 

35INTERNATIONAL_WORDS_PATTERN = re.compile( 

36 b"[a-zA-Z]*[\x80-\xFF]+[a-zA-Z]*[^a-zA-Z\x80-\xFF]?" 

37) 

38 

39 

40class CharSetProber: 

41 

42 SHORTCUT_THRESHOLD = 0.95 

43 

44 def __init__(self, lang_filter: LanguageFilter = LanguageFilter.NONE) -> None: 

45 self._state = ProbingState.DETECTING 

46 self.active = True 

47 self.lang_filter = lang_filter 

48 self.logger = logging.getLogger(__name__) 

49 

50 def reset(self) -> None: 

51 self._state = ProbingState.DETECTING 

52 

53 @property 

54 def charset_name(self) -> Optional[str]: 

55 return None 

56 

57 @property 

58 def language(self) -> Optional[str]: 

59 raise NotImplementedError 

60 

61 def feed(self, byte_str: Union[bytes, bytearray]) -> ProbingState: 

62 raise NotImplementedError 

63 

64 @property 

65 def state(self) -> ProbingState: 

66 return self._state 

67 

68 def get_confidence(self) -> float: 

69 return 0.0 

70 

71 @staticmethod 

72 def filter_high_byte_only(buf: Union[bytes, bytearray]) -> bytes: 

73 buf = re.sub(b"([\x00-\x7F])+", b" ", buf) 

74 return buf 

75 

76 @staticmethod 

77 def filter_international_words(buf: Union[bytes, bytearray]) -> bytearray: 

78 """ 

79 We define three types of bytes: 

80 alphabet: english alphabets [a-zA-Z] 

81 international: international characters [\x80-\xFF] 

82 marker: everything else [^a-zA-Z\x80-\xFF] 

83 The input buffer can be thought to contain a series of words delimited 

84 by markers. This function works to filter all words that contain at 

85 least one international character. All contiguous sequences of markers 

86 are replaced by a single space ascii character. 

87 This filter applies to all scripts which do not use English characters. 

88 """ 

89 filtered = bytearray() 

90 

91 # This regex expression filters out only words that have at-least one 

92 # international character. The word may include one marker character at 

93 # the end. 

94 words = INTERNATIONAL_WORDS_PATTERN.findall(buf) 

95 

96 for word in words: 

97 filtered.extend(word[:-1]) 

98 

99 # If the last character in the word is a marker, replace it with a 

100 # space as markers shouldn't affect our analysis (they are used 

101 # similarly across all languages and may thus have similar 

102 # frequencies). 

103 last_char = word[-1:] 

104 if not last_char.isalpha() and last_char < b"\x80": 

105 last_char = b" " 

106 filtered.extend(last_char) 

107 

108 return filtered 

109 

110 @staticmethod 

111 def remove_xml_tags(buf: Union[bytes, bytearray]) -> bytes: 

112 """ 

113 Returns a copy of ``buf`` that retains only the sequences of English 

114 alphabet and high byte characters that are not between <> characters. 

115 This filter can be applied to all scripts which contain both English 

116 characters and extended ASCII characters, but is currently only used by 

117 ``Latin1Prober``. 

118 """ 

119 filtered = bytearray() 

120 in_tag = False 

121 prev = 0 

122 buf = memoryview(buf).cast("c") 

123 

124 for curr, buf_char in enumerate(buf): 

125 # Check if we're coming out of or entering an XML tag 

126 

127 # https://github.com/python/typeshed/issues/8182 

128 if buf_char == b">": # type: ignore[comparison-overlap] 

129 prev = curr + 1 

130 in_tag = False 

131 # https://github.com/python/typeshed/issues/8182 

132 elif buf_char == b"<": # type: ignore[comparison-overlap] 

133 if curr > prev and not in_tag: 

134 # Keep everything after last non-extended-ASCII, 

135 # non-alphabetic character 

136 filtered.extend(buf[prev:curr]) 

137 # Output a space to delimit stretch we kept 

138 filtered.extend(b" ") 

139 in_tag = True 

140 

141 # If we're not in a tag... 

142 if not in_tag: 

143 # Keep everything after last non-extended-ASCII, non-alphabetic 

144 # character 

145 filtered.extend(buf[prev:]) 

146 

147 return filtered