automaton__epsilon_closure Subroutine

private pure recursive subroutine automaton__epsilon_closure(self, closure, n_index)

Uses

Compute the ε-closure for a set of NFA states.

The ε-closure is the set of NFA states reachable from a given set of NFA states via ε-transition. This subroutine calculates the ε-closure and stores it in the closure parameter.

Type Bound

automaton_t

Arguments

Type IntentOptional Attributes Name
class(automaton_t), intent(inout) :: self
type(nfa_state_set_t), intent(inout) :: closure
integer, intent(in) :: n_index

Source Code

   pure recursive subroutine automaton__epsilon_closure(self, closure, n_index)
      use :: forgex_nfa_node_m
      implicit none
      class(automaton_t), intent(inout) :: self
      type(nfa_state_set_t), intent(inout) :: closure
      integer, intent(in) :: n_index

      type(nfa_state_node_t) :: n_node
      type(nfa_transition_t) :: n_tra
      integer :: j

      call add_nfa_state(closure, n_index)

      n_node = self%nfa%nodes(n_index)

      if (.not. allocated(n_node%forward)) return

       ! すべての順方向の遷移をスキャンする
      do j = 1, n_node%forward_top
         ! 一時変数にコピー
         n_tra = n_node%forward(j)

         if (.not. allocated(n_tra%c)) cycle

         if (any(n_tra%c == SEG_EPSILON) .and. .not. check_nfa_state(closure, n_tra%dst)) then
            if (n_tra%dst /= NFA_NULL_TRANSITION) call self%epsilon_closure(closure, n_tra%dst)
         end if

      end do

   end subroutine automaton__epsilon_closure