automaton__register_state Subroutine

   pure subroutine automaton__register_state(self, state_set, res)
      implicit none
      class(automaton_t),    intent(inout) :: self
      type(nfa_state_set_t), intent(in)    :: state_set
      integer(int32),        intent(inout) :: res       ! resulting the new dfa index

      integer(int32) :: i

      ! If the set is already registered, returns the index of the corresponding DFA state.
      i = self%dfa%registered(state_set)
      if ( i /= DFA_INVALID_INDEX) then
         res = i
         return
      end if

      ! Execute an error stop statement if the counter exceeds a limit.
      if (self%dfa%dfa_top >= self%dfa%dfa_limit) then
         ! Reallocate
         call self%dfa%reallocate()
      end if

      !> @note The processing here should reflect the semantic change of `dfa_top`.
      i = self%dfa%dfa_top
      self%dfa%dfa_top = i + 1 ! increment dfa_top


      self%dfa%nodes(i)%nfa_set    = state_set
      self%dfa%nodes(i)%accepted   = check_nfa_state(state_set, self%nfa_exit)
      self%dfa%nodes(i)%registered = .true.

      call self%dfa%nodes(i)%increment_tra_top() ! Somehow this is necessary!

      res = i

   end subroutine automaton__register_state