Module objectiveFunctions

  Use ISO_FORTRAN_ENV, ONLY: WP=>REAL64

  Implicit NONE

  Type, ABSTRACT :: objective_function_t

  Contains

    Procedure(objfn), DEFERRED :: fun

  End Type

  Type, ABSTRACT :: objective_functions_t

  Contains
    Procedure(mobjfn), DEFERRED :: funs
  End Type

  Type, ABSTRACT :: objective_function_deriv_t

  Contains

    Procedure(derivobjfn), DEFERRED :: fun_deriv

  End Type

  Type, ABSTRACT :: constraint_function_t

  Contains

     Procedure(consfn), DEFERRED :: confun

  End Type

  ABSTRACT INTERFACE

    Function objfn(this, x) RESULT (f)

      IMPORT :: objective_function_t, WP

      Implicit NONE

      Class(objective_function_t), Intent(INOUT) :: this
      Real(WP),                    Intent(IN)    :: x(:)
      Real(WP)                                   :: f

    End Function objfn

    Function derivobjfn(this, x) RESULT (fderiv)

      IMPORT :: objective_function_deriv_t, WP

      Implicit NONE

      Class(objective_function_deriv_t), Intent(INOUT) :: this
      Real(WP),                          Intent(IN)    :: x(:)
      Real(WP)                                         :: fderiv

    End Function derivobjfn

    Subroutine mobjfn(this, x, f)

      IMPORT :: objective_functions_t, WP

      Implicit NONE

      Class(objective_functions_t), Intent(INOUT) :: this
      Real(WP),                     Intent(IN)    :: x(:,:)
      Real(WP),                     Intent(INOUT) :: f(:)

    End Subroutine mobjfn

    Subroutine consfn(this, x, penalty, constraint)

      IMPORT :: constraint_function_t, WP

      Implicit NONE

      Class(constraint_function_t), Intent(INOUT) :: this
      Real(WP),                     Intent(IN)    :: x(:,:)
      Real(WP),                     Intent(IN)    :: penalty
      Real(WP),                     Intent(INOUT) :: constraint(:)

    End Subroutine consfn 

  End Interface

End module objectiveFunctions