autoptr 0.3.4-beta

Autoptr

C++-style smart pointers for D using std.experimental.allocator.

This library contains:

• SharedPtr is a smart pointer that retains shared ownership of an object through a pointer. Support weak pointers and aliasing like C++ std::shared_ptr. Pointer to managed object is separated from pointer to control block conataining reference counter. SharedPtr contains 2 pointers or 2 pointers + length if managed object is slice).
• RcPtr is a smart pointer that retains shared ownership of an object through a pointer. Support weak pointers and only limited aliasing unlike SharedPtr. Managed object must be allcoated with control block (reference counter) in one continuous memory block. RcPtr contains only 1 pointer or 1 pointer + length if managed object is slice.
• UniquePtr is a smart pointer that owns and manages object through a pointer and disposes of that object when the UniquePtr goes out of scope.

SharedPtr, RcPtr and UniquePtr contains 3 template parameters:

• _Type type of managed object.
• _DestructorType type reprezenting attributes of destructor for managed object.
• This parameter is inferred from parameter _Type like this: autoptr.common.DestructorType!_Type.
• _ControlType type reprezenting control block. This parameter specify reference counting for smart pointer.
• Default value for UniquePtr is ControlBlock!void which mean that there is no reference counting.
• Default value for SharedPtr and RefPtr is ControlBlock!(int, int) which mean that type of reference counter is int and weak reference counter type is int. ControlBlock!(int, void) disable weak reference counting.
• If control block is shared then reference counting is atomic. Qualiffier shared is inferred from _Type for _ControlType. If _Type is shared then ControlBlock is shared too.

Smart pointers can be created with static methods make and alloc.

• make create smart pointer with stateless allocator (default Mallocator)
• alloc create smart pointer using allcoator with state. Allcoator is saved in control block.

Constructors of smart pointers never allcoate memory, only static methods make and alloc allcoate.

Documentation

https://submada.github.io/autoptr

Examples

class Foo{
    int i;

    this(int i)pure nothrow @safe @nogc{
        this.i = i;
    }
}

class Bar : Foo{
    double d;

    this(int i, double d)pure nothrow @safe @nogc{
        super(i);
        this.d = d;
    }
}

class Zee : Bar{
    bool b;

    this(int i, double d, bool b)pure nothrow @safe @nogc{
        super(i, d);
        this.b = b;
    }

    ~this()nothrow @system{
    }
}

///`SharedPtr`:
unittest{
    ///simple:
    {
        SharedPtr!long a = SharedPtr!long.make(42);
        assert(a.useCount == 1);

        SharedPtr!(const long) b = a;
        assert(a.useCount == 2);

        SharedPtr!long.WeakType w = a.weak; //or WeakPtr!long
        assert(a.useCount == 2);
        assert(a.weakCount == 1);

        SharedPtr!long c = w.lock;
        assert(a.useCount == 3);
        assert(a.weakCount == 1);

        assert(*c == 42);
        assert(c.get == 42);
    }

    ///polymorphism and aliasing:
    {
        ///create SharedPtr
        SharedPtr!Foo foo = SharedPtr!Bar.make(42, 3.14);
        SharedPtr!Zee zee = SharedPtr!Zee.make(42, 3.14, false);

        ///dynamic cast:
        SharedPtr!Bar bar = dynCast!Bar(foo);
        assert(bar != null);
        assert(foo.useCount == 2);

        ///this doesnt work because Foo destructor attributes are more restrictive then Zee's:
        //SharedPtr!Foo x = zee;

        ///this does work:
        SharedPtr!(Foo, DestructorType!(Foo, Zee)) x = zee;
        assert(zee.useCount == 2);

        ///aliasing (shared ptr `d` share ref counting with `bar`):
        SharedPtr!double d = SharedPtr!double(bar, &bar.get.d);
        assert(d != null);
        assert(*d == 3.14);
        assert(foo.useCount == 3);
    }


    ///multi threading:
    {
        ///create SharedPtr with atomic ref counting
        SharedPtr!(shared Foo) foo = SharedPtr!(shared Bar).make(42, 3.14);

        ///this doesnt work:
        //foo.get.i += 1;

        import core.atomic : atomicFetchAdd;
        atomicFetchAdd(foo.get.i, 1);
        assert(foo.get.i == 43);


        ///creating `shared(SharedPtr)`:
        shared SharedPtr!(shared Bar) bar = share(dynCast!Bar(foo));

        ///`shared(SharedPtr)` is not lock free but `RcPtr` is lock free.
        static assert(typeof(bar).isLockFree == false);

        ///multi thread operations (`load`, `store`, `exchange` and `compareExchange`):
        SharedPtr!(shared Bar) bar2 = bar.load();
        assert(bar2 != null);
        assert(bar2.useCount == 3);

        SharedPtr!(shared Bar) bar3 = bar.exchange(null);
        assert(bar3 != null);
        assert(bar3.useCount == 3);
    }

    ///dynamic array:
    {
        import std.algorithm : all, equal;

        SharedPtr!(long[]) a = SharedPtr!(long[]).make(10, -1);
        assert(a.length == 10);
        assert(a.get.length == 10);
        assert(a.get.all!(x => x == -1));

        for(long i = 0; i < a.length; ++i){
            a.get[i] = i;
        }
        assert(a.get[] == [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

        ///aliasing:
        SharedPtr!long a6 = SharedPtr!long(a, &a.get[6]);
        assert(*a6 == a.get[6]);
    }
}

///`UniquePtr`:
unittest{
    ///simple:
    {
        SharedPtr!long a = SharedPtr!long.make(42);
        SharedPtr!(const long) b = a.move;
        assert(a == null);

        assert(*b == 42);
        assert(b.get == 42);
    }

    ///polymorphism:
    {
        ///create UniquePtr
        UniquePtr!Foo foo = UniquePtr!Bar.make(42, 3.14);
        UniquePtr!Zee zee = UniquePtr!Zee.make(42, 3.14, false);

        ///dynamic cast:
        UniquePtr!Bar bar = dynCastMove!Bar(foo);
        assert(foo == null);
        assert(bar != null);

        ///this doesnt work because Foo destructor attributes are more restrictive then Zee's:
        //UniquePtr!Foo x = zee.move;

        ///this does work:
        UniquePtr!(Foo, DestructorType!(Foo, Zee)) x = zee.move;
        assert(zee == null);
    }


    ///multi threading:
    {
        ///create SharedPtr with atomic ref counting
        UniquePtr!(shared Foo) foo = UniquePtr!(shared Bar).make(42, 3.14);

        ///this doesnt work:
        //foo.get.i += 1;

        import core.atomic : atomicFetchAdd;
        atomicFetchAdd(foo.get.i, 1);
        assert(foo.get.i == 43);


        ///creating `shared(UniquePtr)`:
        shared UniquePtr!(shared Bar) bar = share(dynCastMove!Bar(foo));

        ///`shared(UniquePtr)` is lock free.
        static assert(typeof(bar).isLockFree == true);

        ///multi thread operations (`store`, `exchange`):
        UniquePtr!(shared Bar) bar2 = bar.exchange(null);
    }

    ///dynamic array:
    {
        import std.algorithm : all, equal;

        UniquePtr!(long[]) a = UniquePtr!(long[]).make(10, -1);
        assert(a.length == 10);
        assert(a.get.length == 10);
        assert(a.get.all!(x => x == -1));

        for(long i = 0; i < a.length; ++i){
            a.get[i] = i;
        }
        assert(a.get[] == [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
    }
}



///`RcPtr`:
unittest{
    ///simple:
    {
        RcPtr!long a = RcPtr!long.make(42);
        assert(a.useCount == 1);

        RcPtr!(const long) b = a;
        assert(a.useCount == 2);

        RcPtr!long.WeakType w = a.weak; //or WeakRcPtr!long
        assert(a.useCount == 2);
        assert(a.weakCount == 1);

        RcPtr!long c = w.lock;
        assert(a.useCount == 3);
        assert(a.weakCount == 1);

        assert(*c == 42);
        assert(c.get == 42);
    }

    ///polymorphism and aliasing:
    {
        ///create RcPtr
        RcPtr!Foo foo = RcPtr!Bar.make(42, 3.14);
        RcPtr!Zee zee = RcPtr!Zee.make(42, 3.14, false);

        ///dynamic cast:
        RcPtr!Bar bar = dynCast!Bar(foo);
        assert(bar != null);
        assert(foo.useCount == 2);

        ///this doesnt work because Foo destructor attributes are more restrictive then Zee's:
        //RcPtr!Foo x = zee;

        ///this does work:
        RcPtr!(Foo, DestructorType!(Foo, Zee)) x = zee;
        assert(zee.useCount == 2);
    }


    ///multi threading:
    {
        ///create RcPtr with atomic ref counting
        RcPtr!(shared Foo) foo = RcPtr!(shared Bar).make(42, 3.14);

        ///this doesnt work:
        //foo.get.i += 1;

        import core.atomic : atomicFetchAdd;
        atomicFetchAdd(foo.get.i, 1);
        assert(foo.get.i == 43);


        ///creating `shared(RcPtr)`:
        shared RcPtr!(shared Bar) bar = share(dynCast!Bar(foo));

        ///`shared(RcPtr)` is lock free (except `load` and `useCount`/`weakCount`).
        static assert(typeof(bar).isLockFree == true);

        ///multi thread operations (`load`, `store`, `exchange` and `compareExchange`):
        RcPtr!(shared Bar) bar2 = bar.load();
        assert(bar2 != null);
        assert(bar2.useCount == 3);

        RcPtr!(shared Bar) bar3 = bar.exchange(null);
        assert(bar3 != null);
        assert(bar3.useCount == 3);
    }

    ///dynamic array:
    {
        import std.algorithm : all, equal;

        RcPtr!(long[]) a = RcPtr!(long[]).make(10, -1);
        assert(a.length == 10);
        assert(a.get.length == 10);
        assert(a.get.all!(x => x == -1));

        for(long i = 0; i < a.length; ++i){
            a.get[i] = i;
        }
        assert(a.get[] == [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
    }
}