(1). Except as provided in section five an assignee of moneys, or any part thereof, due or to become due under a contract for public improvement, whose assignment is duly filed prior to the filing of a notice of lien or assignment of every other party to the action, shall have priority over those parties to the extent of advances made upon such assignment before the filing of the notice of lien or assignment next subsequent to his assignment, but as to advances made subsequent to a notice of lien or assignment filed and unsatisfied or not discharged such assignee for the purpose of determining his proportionate share of moneys available for distribution as provided in subdivision four of this section shall be treated as a lienor having a lien to the extent of advances so made.

(2) An assignee of moneys or any part thereof, due or to become due under a contract for a public improvement whose assignment is duly filed subsequent to the filing of the notice of lien or assignment of any other party shall for the purpose of determining his proportionate share of moneys available for distribution, as provided in subdivision four of this section be treated as a lienor having a lien to the extent of advances actually made upon such assignment prior to the filing thereof.

(3) Laborers for daily or weekly wages having liens under a contract for a public improvement, shall have preference as a class for the full amount of their unpaid wages over all other lienors having liens arising under the same contract and without reference to the time when such laborers shall have filed their notices of liens.

(4) There shall be no priority among labor lienors, as a class or among other lienors as a class, and any moneys available for distribution among lienors of any class shall be distributed pro rata in accordance with their respective valid liens.

(5) Every assignment of moneys, or any part thereof, due or to become due under a contract for a public improvement shall contain a covenant by the assignor that he will receive any moneys advanced thereunder by the assignee and will hold the right to receive such moneys as a trust fund to be first applied to the payment of trust claims as defined in section seventy-one of the lien law, and that he will apply the same to such payments only, before using any part of the moneys for any other purpose.