59 lines
2 KiB
Python
59 lines
2 KiB
Python
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from emis_funky_funktions import *
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from typing import AbstractSet, FrozenSet, TypeAlias, TypeGuard, TypeVar
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Lexeme = TypeVar('Lexeme')
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Token = TypeVar('Token')
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Variable = TypeVar('Variable')
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Handle: TypeAlias = Sequence[Variable | Token]
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Production: TypeAlias = Tuple[Variable, Handle[Variable, Token]]
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Grammar: TypeAlias = Sequence[Production[Variable, Token]]
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NfaState: TypeAlias = Tuple[int, int]
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Nfa: TypeAlias = Callable[[NfaState, Variable | Token], FrozenSet[NfaState]]
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DfaState: TypeAlias = FrozenSet(Tuple[int, int])
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Dfa: TypeAlias = Callable[[DfaState, Variable | Token], FrozenSet[NfaState]]
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def build_nfa(
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is_var: Callable[[Variable | Token], TypeGuard[Variable]],
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grammar: Grammar[Variable, Token],
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) -> Nfa[Variable, Token]:
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def epsilon_closure_step(state: NfaState) -> FrozenSet[NfaState]:
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production_no, symbol_no = state
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_, production = grammar[production_no]
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next_symbol = production[symbol_no]
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if is_var(next_symbol):
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possible_productions: Iterator[NfaState] = ((i, 0) for i, (variable, handle) in enumerate(grammar) if variable == next_symbol)
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return fset(state, *possible_productions)
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else:
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return fset(state,)
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def epsilon_closure(states: FrozenSet[NfaState], previous_states: FrozenSet[NfaState] = fset()) -> FrozenSet[NfaState]:
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new_states = FSet(new_state for old_state in states for new_state in epsilon_closure_step(old_state)) - previous_states - states
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if len(new_states) == 0:
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return states | previous_states
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else:
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return epsilon_closure(new_states, states | previous_states)
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def nfa(state: Tuple[int, int], symbol: Variable | Token) -> FrozenSet[NfaState]:
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production_no, symbol_no = state
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production = grammar[production_no]
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next_symbol = production[symbol_no]
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if next_symbol == symbol:
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return epsilon_closure(fset((production_no, symbol_no + 1)))
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else:
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return fset()
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def dfa(dstate: DfaState, symbol: Variable | Token) -> DfaState:
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return FSet(
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new_nstate
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for nstate in dstate
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for new_nstate in nfa(nstate, symbol)
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)
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return nfa
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