typedef enum logic [1:0] {
  TWO_LEGS,
  FOUR_LEGS,
  SIX_LEGS,
  EIGHT_LEGS
} leg_e;

typedef enum logic [2:0] {
  HUMAN,
  DOGS,
  CAT,
  ELEPHANT,
  FLY,
  COCKROACH,
  SPIDER
} animal_e;

class parameterized_class #( type enum_type);
  static int initial_allocation;
  static enum_type list[$];

  rand int unsigned ptr;

  constraint ptr_c {
            ptr < list.size();
  }

 function new();
   enum_type my_enum;
    if(initial_allocation == 0) begin
      initial_allocation = 1;
      for(int unsigned i = 0; i < my_enum.num(); i++)
        repeat($urandom_range(1,10)) list.push_back(my_enum);
    end
  endfunction
endclass

class random_class;
  rand parameterized_class#(leg_e) leg_select;
  rand parameterized_class#(animal_e) animal_select;

  rand leg_e leg_q[$];
  rand animal_e animal_q[$];

  constraint leg_animal_c {
      leg_select.list[leg_select.ptr] == TWO_LEGS -> animal_select.list[animal_select.ptr] inside {HUMAN};
      leg_select.list[leg_select.ptr] == FOUR_LEGS -> animal_select.list[animal_select.ptr] inside {DOGS, CAT, ELEPHANT};
      leg_select.list[leg_select.ptr] == SIX_LEGS -> animal_select.list[animal_select.ptr] inside {FLY, COCKROACH};
      leg_select.list[leg_select.ptr] == EIGHT_LEGS -> animal_select.list[animal_select.ptr] inside {SPIDER};
  }

  constraint q_c {
      leg_q.size() dist {[0:5] := 50, [6:10] := 50};
      animal_q.size() == leg_q.size();
  }
  function new();
    leg_select = new;
    animal_select = new;
  endfunction
endclass

module tb;
  initial begin
    random_class rnd = new;
    repeat (10) begin
      rnd.randomize();
      $display("Animals in queue = %p", rnd.animal_q);
      $display("Legs in queue = %p", rnd.leg_q);
    end
  end
endmodule