Source code for chardet.codingstatemachine

######################## 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.
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# Contributor(s):
#   Mark Pilgrim - port to Python
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# Lesser General Public License for more details.
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import logging

from .enums import MachineState


[docs]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): self._model = sm self._curr_byte_pos = 0 self._curr_char_len = 0 self._curr_state = None self.logger = logging.getLogger(__name__) self.reset()
[docs] def reset(self): self._curr_state = MachineState.START
[docs] def next_state(self, c): # 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
[docs] def get_current_charlen(self): return self._curr_char_len
[docs] def get_coding_state_machine(self): return self._model["name"]
@property def language(self): return self._model["language"]