1! { dg-do run }
2!
3! PR fortran/51972
4!
5! Contributed by Damian Rouson
6!
7module surrogate_module
8  type ,abstract :: surrogate
9  end type
10end module
11
12module strategy_module
13  use surrogate_module
14
15  type :: strategy
16  end type
17end module
18
19module integrand_module
20  use surrogate_module
21  use strategy_module
22  implicit none
23
24  type ,abstract, extends(surrogate) :: integrand
25    class(strategy), allocatable :: quadrature
26  end type
27end module integrand_module
28
29module lorenz_module
30  use strategy_module
31  use integrand_module
32  implicit none
33
34  type ,extends(integrand) :: lorenz
35    real, dimension(:), allocatable :: state
36  contains
37    procedure ,public :: assign   => assign_lorenz
38  end type
39contains
40  type(lorenz) function constructor(initial_state, this_strategy)
41    real ,dimension(:) ,intent(in)  :: initial_state
42    class(strategy)    ,intent(in)  :: this_strategy
43    constructor%state=initial_state
44    allocate (constructor%quadrature, source=this_strategy)
45  end function
46
47  subroutine assign_lorenz(lhs,rhs)
48    class(lorenz)    ,intent(inout) :: lhs
49    class(integrand) ,intent(in)    :: rhs
50    select type(rhs)
51      class is (lorenz)
52        allocate (lhs%quadrature, source=rhs%quadrature)
53        lhs%state=rhs%state
54    end select
55  end subroutine
56end module lorenz_module
57
58module runge_kutta_2nd_module
59  use surrogate_module,only : surrogate
60  use strategy_module ,only : strategy
61  use integrand_module,only : integrand
62  implicit none
63
64  type, extends(strategy) ,public :: runge_kutta_2nd
65  contains
66    procedure, nopass :: integrate
67  end type
68contains
69  subroutine integrate(this)
70    class(surrogate) ,intent(inout) :: this
71    class(integrand) ,allocatable   :: this_half
72
73    select type (this)
74      class is (integrand)
75        allocate (this_half, source=this)
76    end select
77  end subroutine
78end module
79
80program main
81  use lorenz_module
82  use runge_kutta_2nd_module ,only : runge_kutta_2nd, integrate
83  implicit none
84
85  type(runge_kutta_2nd) :: timed_lorenz_integrator
86  type(lorenz)          :: attractor
87
88  attractor = constructor( [1., 1., 1.] , timed_lorenz_integrator)
89  call integrate(attractor)
90end program main
91