module tree

  use typedef, only: &
       int64

  implicit none

  save

  integer(kind=int64) :: &
       nstar = -1
  integer(kind=int64), dimension(:), allocatable :: &
       order, hierarchy

contains

  subroutine clear_order()

    if (allocated(order)) deallocate(order)
    if (allocated(hierarchy)) deallocate(hierarchy)
    nstar = -1

  end subroutine clear_order


  subroutine set_order(order_, hierarchy_)

    use typedef, only: &
         int64

    integer(kind=int64), dimension(:), intent(in) :: &
         order_, hierarchy_

    integer(kind=int64) :: &
         nstar_

    nstar_ = size(order_, 1)
    if (size(hierarchy_, 1) /= nstar_) &
         error stop 'dimension mismatch for order and hierarchy'

    if (nstar /= nstar_) then
       if (allocated(order)) deallocate(order)
       if (allocated(hierarchy)) deallocate(hierarchy)
       nstar = nstar_
       allocate(order(nstar), hierarchy(nstar))
    endif

    order(:) = order_(:)
    hierarchy(:) = hierarchy_(:)

  end subroutine set_order




end module tree