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| ######################## BEGIN LICENSE BLOCK ######################## | |
| # The Original Code is mozilla.org code. | |
| # | |
| # The Initial Developer of the Original Code is | |
| # Netscape Communications Corporation. | |
| # Portions created by the Initial Developer are Copyright (C) 1998 | |
| # the Initial Developer. All Rights Reserved. | |
| # | |
| # Contributor(s): | |
| # Mark Pilgrim - port to Python | |
| # | |
| # This library is free software; you can redistribute it and/or | |
| # modify it under the terms of the GNU Lesser General Public | |
| # License as published by the Free Software Foundation; either | |
| # version 2.1 of the License, or (at your option) any later version. | |
| # | |
| # This library is distributed in the hope that it will be useful, | |
| # but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| # Lesser General Public License for more details. | |
| # | |
| # You should have received a copy of the GNU Lesser General Public | |
| # License along with this library; if not, write to the Free Software | |
| # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA | |
| # 02110-1301 USA | |
| ######################### END LICENSE BLOCK ######################### | |
| import logging | |
| from .codingstatemachinedict import CodingStateMachineDict | |
| from .enums import MachineState | |
| class CodingStateMachine: | |
| """ | |
| A state machine to verify a byte sequence for a particular encoding. For | |
| each byte the detector receives, it will feed that byte to every active | |
| state machine available, one byte at a time. The state machine changes its | |
| state based on its previous state and the byte it receives. There are 3 | |
| states in a state machine that are of interest to an auto-detector: | |
| START state: This is the state to start with, or a legal byte sequence | |
| (i.e. a valid code point) for character has been identified. | |
| ME state: This indicates that the state machine identified a byte sequence | |
| that is specific to the charset it is designed for and that | |
| there is no other possible encoding which can contain this byte | |
| sequence. This will to lead to an immediate positive answer for | |
| the detector. | |
| ERROR state: This indicates the state machine identified an illegal byte | |
| sequence for that encoding. This will lead to an immediate | |
| negative answer for this encoding. Detector will exclude this | |
| encoding from consideration from here on. | |
| """ | |
| def __init__(self, sm: CodingStateMachineDict) -> None: | |
| self._model = sm | |
| self._curr_byte_pos = 0 | |
| self._curr_char_len = 0 | |
| self._curr_state = MachineState.START | |
| self.active = True | |
| self.logger = logging.getLogger(__name__) | |
| self.reset() | |
| def reset(self) -> None: | |
| self._curr_state = MachineState.START | |
| def next_state(self, c: int) -> int: | |
| # for each byte we get its class | |
| # if it is first byte, we also get byte length | |
| byte_class = self._model["class_table"][c] | |
| if self._curr_state == MachineState.START: | |
| self._curr_byte_pos = 0 | |
| self._curr_char_len = self._model["char_len_table"][byte_class] | |
| # from byte's class and state_table, we get its next state | |
| curr_state = self._curr_state * self._model["class_factor"] + byte_class | |
| self._curr_state = self._model["state_table"][curr_state] | |
| self._curr_byte_pos += 1 | |
| return self._curr_state | |
| def get_current_charlen(self) -> int: | |
| return self._curr_char_len | |
| def get_coding_state_machine(self) -> str: | |
| return self._model["name"] | |
| def language(self) -> str: | |
| return self._model["language"] | |