103 lines
3.9 KiB
Python
103 lines
3.9 KiB
Python
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######################## BEGIN LICENSE BLOCK ########################
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# The Original Code is mozilla.org code.
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#
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# The Initial Developer of the Original Code is
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# Netscape Communications Corporation.
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# Portions created by the Initial Developer are Copyright (C) 1998
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# the Initial Developer. All Rights Reserved.
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#
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# Contributor(s):
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# Mark Pilgrim - port to Python
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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# 02110-1301 USA
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######################### END LICENSE BLOCK #########################
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from typing import Optional, Union
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from .charsetprober import CharSetProber
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from .codingstatemachine import CodingStateMachine
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from .enums import LanguageFilter, MachineState, ProbingState
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from .escsm import (
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HZ_SM_MODEL,
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ISO2022CN_SM_MODEL,
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ISO2022JP_SM_MODEL,
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ISO2022KR_SM_MODEL,
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)
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class EscCharSetProber(CharSetProber):
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"""
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This CharSetProber uses a "code scheme" approach for detecting encodings,
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whereby easily recognizable escape or shift sequences are relied on to
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identify these encodings.
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"""
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def __init__(self, lang_filter: LanguageFilter = LanguageFilter.NONE) -> None:
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super().__init__(lang_filter=lang_filter)
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self.coding_sm = []
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if self.lang_filter & LanguageFilter.CHINESE_SIMPLIFIED:
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self.coding_sm.append(CodingStateMachine(HZ_SM_MODEL))
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self.coding_sm.append(CodingStateMachine(ISO2022CN_SM_MODEL))
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if self.lang_filter & LanguageFilter.JAPANESE:
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self.coding_sm.append(CodingStateMachine(ISO2022JP_SM_MODEL))
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if self.lang_filter & LanguageFilter.KOREAN:
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self.coding_sm.append(CodingStateMachine(ISO2022KR_SM_MODEL))
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self.active_sm_count = 0
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self._detected_charset: Optional[str] = None
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self._detected_language: Optional[str] = None
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self._state = ProbingState.DETECTING
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self.reset()
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def reset(self) -> None:
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super().reset()
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for coding_sm in self.coding_sm:
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coding_sm.active = True
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coding_sm.reset()
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self.active_sm_count = len(self.coding_sm)
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self._detected_charset = None
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self._detected_language = None
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@property
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def charset_name(self) -> Optional[str]:
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return self._detected_charset
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@property
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def language(self) -> Optional[str]:
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return self._detected_language
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def get_confidence(self) -> float:
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return 0.99 if self._detected_charset else 0.00
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def feed(self, byte_str: Union[bytes, bytearray]) -> ProbingState:
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for c in byte_str:
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for coding_sm in self.coding_sm:
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if not coding_sm.active:
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continue
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coding_state = coding_sm.next_state(c)
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if coding_state == MachineState.ERROR:
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coding_sm.active = False
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self.active_sm_count -= 1
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if self.active_sm_count <= 0:
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self._state = ProbingState.NOT_ME
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return self.state
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elif coding_state == MachineState.ITS_ME:
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self._state = ProbingState.FOUND_IT
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self._detected_charset = coding_sm.get_coding_state_machine()
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self._detected_language = coding_sm.language
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return self.state
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return self.state
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