python (3.11.7)
1 ######################## BEGIN LICENSE BLOCK ########################
2 # The Original Code is mozilla.org 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) 1998
7 # the Initial Developer. All Rights Reserved.
8 #
9 # Contributor(s):
10 # Mark Pilgrim - port to Python
11 #
12 # This library is free software; you can redistribute it and/or
13 # modify it under the terms of the GNU Lesser General Public
14 # License as published by the Free Software Foundation; either
15 # version 2.1 of the License, or (at your option) any later version.
16 #
17 # This library is distributed in the hope that it will be useful,
18 # but WITHOUT ANY WARRANTY; without even the implied warranty of
19 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 # Lesser General Public License for more details.
21 #
22 # You should have received a copy of the GNU Lesser General Public
23 # License along with this library; if not, write to the Free Software
24 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
25 # 02110-1301 USA
26 ######################### END LICENSE BLOCK #########################
27
28 from typing import Union
29
30 from .charsetprober import CharSetProber
31 from .codingstatemachine import CodingStateMachine
32 from .enums import MachineState, ProbingState
33 from .mbcssm import UTF8_SM_MODEL
34
35
36 class ESC[4;38;5;81mUTF8Prober(ESC[4;38;5;149mCharSetProber):
37 ONE_CHAR_PROB = 0.5
38
39 def __init__(self) -> None:
40 super().__init__()
41 self.coding_sm = CodingStateMachine(UTF8_SM_MODEL)
42 self._num_mb_chars = 0
43 self.reset()
44
45 def reset(self) -> None:
46 super().reset()
47 self.coding_sm.reset()
48 self._num_mb_chars = 0
49
50 @property
51 def charset_name(self) -> str:
52 return "utf-8"
53
54 @property
55 def language(self) -> str:
56 return ""
57
58 def feed(self, byte_str: Union[bytes, bytearray]) -> ProbingState:
59 for c in byte_str:
60 coding_state = self.coding_sm.next_state(c)
61 if coding_state == MachineState.ERROR:
62 self._state = ProbingState.NOT_ME
63 break
64 if coding_state == MachineState.ITS_ME:
65 self._state = ProbingState.FOUND_IT
66 break
67 if coding_state == MachineState.START:
68 if self.coding_sm.get_current_charlen() >= 2:
69 self._num_mb_chars += 1
70
71 if self.state == ProbingState.DETECTING:
72 if self.get_confidence() > self.SHORTCUT_THRESHOLD:
73 self._state = ProbingState.FOUND_IT
74
75 return self.state
76
77 def get_confidence(self) -> float:
78 unlike = 0.99
79 if self._num_mb_chars < 6:
80 unlike *= self.ONE_CHAR_PROB**self._num_mb_chars
81 return 1.0 - unlike
82 return unlike
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