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# Proofpoint, Inc.
13#
14# This library is free software; you can redistribute it and/or
15# modify it under the terms of the GNU Lesser General Public
16# License as published by the Free Software Foundation; either
17# version 2.1 of the License, or (at your option) any later version.
18#
19# This library is distributed in the hope that it will be useful,
20# but WITHOUT ANY WARRANTY; without even the implied warranty of
21# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22# Lesser General Public License for more details.
23#
24# You should have received a copy of the GNU Lesser General Public
25# License along with this library; if not, write to the Free Software
26# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
27# 02110-1301 USA
28######################### END LICENSE BLOCK #########################
29
30from typing import Optional, Union
31
32from .chardistribution import CharDistributionAnalysis
33from .charsetprober import CharSetProber
34from .codingstatemachine import CodingStateMachine
35from .enums import LanguageFilter, MachineState, ProbingState
36
37
38class MultiByteCharSetProber(CharSetProber):
39 """
40 MultiByteCharSetProber
41 """
42
43 def __init__(self, lang_filter: LanguageFilter = LanguageFilter.NONE) -> None:
44 super().__init__(lang_filter=lang_filter)
45 self.distribution_analyzer: Optional[CharDistributionAnalysis] = None
46 self.coding_sm: Optional[CodingStateMachine] = None
47 self._last_char = bytearray(b"\0\0")
48
49 def reset(self) -> None:
50 super().reset()
51 if self.coding_sm:
52 self.coding_sm.reset()
53 if self.distribution_analyzer:
54 self.distribution_analyzer.reset()
55 self._last_char = bytearray(b"\0\0")
56
57 def feed(self, byte_str: Union[bytes, bytearray]) -> ProbingState:
58 assert self.coding_sm is not None
59 assert self.distribution_analyzer is not None
60
61 for i, byte in enumerate(byte_str):
62 coding_state = self.coding_sm.next_state(byte)
63 if coding_state == MachineState.ERROR:
64 self.logger.debug(
65 "%s %s prober hit error at byte %s",
66 self.charset_name,
67 self.language,
68 i,
69 )
70 self._state = ProbingState.NOT_ME
71 break
72 if coding_state == MachineState.ITS_ME:
73 self._state = ProbingState.FOUND_IT
74 break
75 if coding_state == MachineState.START:
76 char_len = self.coding_sm.get_current_charlen()
77 if i == 0:
78 self._last_char[1] = byte
79 self.distribution_analyzer.feed(self._last_char, char_len)
80 else:
81 self.distribution_analyzer.feed(byte_str[i - 1 : i + 1], char_len)
82
83 self._last_char[0] = byte_str[-1]
84
85 if self.state == ProbingState.DETECTING:
86 if self.distribution_analyzer.got_enough_data() and (
87 self.get_confidence() > self.SHORTCUT_THRESHOLD
88 ):
89 self._state = ProbingState.FOUND_IT
90
91 return self.state
92
93 def get_confidence(self) -> float:
94 assert self.distribution_analyzer is not None
95 return self.distribution_analyzer.get_confidence()