build_vertex_order Module Subroutine

  module subroutine build_vertex_order(this)
    !! Generate the order of the layers in the network
    !!
    !! This module contains the subroutine to generate the order of the layers
    !! in the network. The order is generated by depth first search (DFS) on the
    !! graph of the network.
    implicit none

    ! Arguments
    class(network_type), intent(inout) :: this
    !! Instance of network

    ! Local variables
    integer :: i, order_index
    !! Loop index
    logical, dimension(this%auto_graph%num_vertices) :: visited
    !! Array to store whether a vertex has been

    visited = .false.
    if(allocated(this%vertex_order)) deallocate(this%vertex_order)
    allocate(this%vertex_order(this%auto_graph%num_vertices), source=0)

    order_index = 0
    do i = this%auto_graph%num_vertices, 1, -1
       if(.not.visited(i)) call this%dfs( &
            i, visited, this%vertex_order, order_index &
       )
    end do

  end subroutine build_vertex_order