Mercurial > repos > shellac > guppy_basecaller

comparison env/lib/python3.7/site-packages/chardet/charsetprober.py @ 0:26e78fe6e8c4 draft

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"planemo upload commit c699937486c35866861690329de38ec1a5d9f783"
author shellac
date Sat, 02 May 2020 07:14:21 -0400
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-1:000000000000 0:26e78fe6e8c4
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
29 import logging
30 import re
31
32 from .enums import ProbingState
33
34
35 class CharSetProber(object):
36
37 SHORTCUT_THRESHOLD = 0.95
38
39 def __init__(self, lang_filter=None):
40 self._state = None
41 self.lang_filter = lang_filter
42 self.logger = logging.getLogger(__name__)
43
44 def reset(self):
45 self._state = ProbingState.DETECTING
46
47 @property
48 def charset_name(self):
49 return None
50
51 def feed(self, buf):
52 pass
53
54 @property
55 def state(self):
56 return self._state
57
58 def get_confidence(self):
59 return 0.0
60
61 @staticmethod
62 def filter_high_byte_only(buf):
63 buf = re.sub(b'([\x00-\x7F])+', b' ', buf)
64 return buf
65
66 @staticmethod
67 def filter_international_words(buf):
68 """
69 We define three types of bytes:
70 alphabet: english alphabets [a-zA-Z]
71 international: international characters [\x80-\xFF]
72 marker: everything else [^a-zA-Z\x80-\xFF]
73
74 The input buffer can be thought to contain a series of words delimited
75 by markers. This function works to filter all words that contain at
76 least one international character. All contiguous sequences of markers
77 are replaced by a single space ascii character.
78
79 This filter applies to all scripts which do not use English characters.
80 """
81 filtered = bytearray()
82
83 # This regex expression filters out only words that have at-least one
84 # international character. The word may include one marker character at
85 # the end.
86 words = re.findall(b'[a-zA-Z]*[\x80-\xFF]+[a-zA-Z]*[^a-zA-Z\x80-\xFF]?',
87 buf)
88
89 for word in words:
90 filtered.extend(word[:-1])
91
92 # If the last character in the word is a marker, replace it with a
93 # space as markers shouldn't affect our analysis (they are used
94 # similarly across all languages and may thus have similar
95 # frequencies).
96 last_char = word[-1:]
97 if not last_char.isalpha() and last_char < b'\x80':
98 last_char = b' '
99 filtered.extend(last_char)
100
101 return filtered
102
103 @staticmethod
104 def filter_with_english_letters(buf):
105 """
106 Returns a copy of ``buf`` that retains only the sequences of English
107 alphabet and high byte characters that are not between <> characters.
108 Also retains English alphabet and high byte characters immediately
109 before occurrences of >.
110
111 This filter can be applied to all scripts which contain both English
112 characters and extended ASCII characters, but is currently only used by
113 ``Latin1Prober``.
114 """
115 filtered = bytearray()
116 in_tag = False
117 prev = 0
118
119 for curr in range(len(buf)):
120 # Slice here to get bytes instead of an int with Python 3
121 buf_char = buf[curr:curr + 1]
122 # Check if we're coming out of or entering an HTML tag
123 if buf_char == b'>':
124 in_tag = False
125 elif buf_char == b'<':
126 in_tag = True
127
128 # If current character is not extended-ASCII and not alphabetic...
129 if buf_char < b'\x80' and not buf_char.isalpha():
130 # ...and we're not in a tag
131 if curr > prev and not in_tag:
132 # Keep everything after last non-extended-ASCII,
133 # non-alphabetic character
134 filtered.extend(buf[prev:curr])
135 # Output a space to delimit stretch we kept
136 filtered.extend(b' ')
137 prev = curr + 1
138
139 # If we're not in a tag...
140 if not in_tag:
141 # Keep everything after last non-extended-ASCII, non-alphabetic
142 # character
143 filtered.extend(buf[prev:])
144
145 return filtered