automaton__initialize Subroutine

   pure subroutine automaton__initialize(self)
      implicit none
      class(automaton_t), intent(inout) :: self

      type(nfa_state_set_t) :: initial_closure
      integer(int32) :: new_index

      !-- DFA initialize
      ! Invokes DFA preprocessing.
      call self%dfa%preprocess()

      ! Check if it has been initialized.
      if (self%dfa%dfa_top /= DFA_INITIAL_INDEX) then
         error stop "DFA graph initialization is failed."
      end if

      call init_state_set(self%entry_set, self%nfa%nfa_top)
      ! Constructing a DFA initial state from the NFA initial state.
      call add_nfa_state(self%entry_set, self%nfa_entry)

      call init_state_set(initial_closure, self%nfa%nfa_top)
      initial_closure = self%entry_set
      ! Add an NFA node reachable by epsilon transitions to the entrance state set within DFA.
      call self%epsilon_closure(initial_closure, self%nfa_entry)

      ! Assign the computed initial closure into self%entry_set
      self%entry_set = initial_closure

      ! Register `entry_set` as a new DFA state in the graph.
      call self%register_state(self%entry_set, new_index)

      ! Assign the returned index to the `initial_index` of the graph.
      self%initial_index = new_index

   end subroutine automaton__initialize