Method: Kleene::DSL#with_err!

Defined in:
lib/kleene/dsl.rb

#with_err!(nfa, alphabet = nfa.alphabet) ⇒ Object

adds and error state to the NFA, create error transitions from all non-error states to the error state on any unhandled token. the error state transitions to itself on any token.



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# File 'lib/kleene/dsl.rb', line 62

def with_err!(nfa, alphabet = nfa.alphabet)
  error_state = nfa.states.find(&:error?)
  return nfa if error_state

  error_state = State.new_error_state
  nfa.add_state(error_state)

  nfa.states.each do |state|
    tokens_on_outbound_transitions = nfa.transitions_from(state).map(&:token)
    missing_tokens = alphabet - tokens_on_outbound_transitions
    missing_tokens.each do |token|
      nfa.add_transition(token, state, error_state)
    end
  end

  nfa.remove_state(error_state) if nfa.all_transitions.none? {|transition| transition.from == error_state || transition.to == error_state }

  nfa.set_regex_pattern("/#{nfa.regex_pattern}/E")
end