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Enable STL-style enable_shared_from_this (#1295)

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Steven Dee (Jōshin) 2024-09-15 19:32:13 -04:00 • committed by GitHub
parent 6397999fca
commit ef62730ae4
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2 changed files with 96 additions and 4 deletions
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65
ctl/shared_ptr.h
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@ -4,6 +4,7 @@
#define CTL_SHARED_PTR_H_
#include "exception.h"
#include "is_base_of.h"
#include "is_convertible.h"
#include "remove_extent.h"
#include "unique_ptr.h"
@ -201,10 +202,7 @@ class shared_ptr
template<typename U, typename D>
requires __::shared_ptr_compatible<T, U>
shared_ptr(U* const p, D d)
: p(p), rc(__::shared_pointer<U, D>::make(p, move(d)))
{
}
shared_ptr(U*, D);
template<typename U>
shared_ptr(const shared_ptr<U>& r, element_type* p) noexcept
@ -443,6 +441,62 @@ class weak_ptr
__::shared_ref* rc = nullptr;
};
template<typename T>
class enable_shared_from_this
{
public:
shared_ptr<T> shared_from_this()
{
return shared_ptr<T>(weak_this);
}
shared_ptr<T const> shared_from_this() const
{
return shared_ptr<T>(weak_this);
}
weak_ptr<T> weak_from_this()
{
return weak_this;
}
weak_ptr<T const> weak_from_this() const
{
return weak_this;
}
protected:
constexpr enable_shared_from_this() noexcept = default;
enable_shared_from_this(const enable_shared_from_this& r) noexcept
{
}
~enable_shared_from_this() = default;
enable_shared_from_this& operator=(
const enable_shared_from_this& r) noexcept
{
return *this;
}
private:
template<typename U, typename... Args>
friend shared_ptr<U> make_shared(Args&&...);
template<typename U>
friend class shared_ptr;
weak_ptr<T> weak_this;
};
template<typename T>
template<typename U, typename D>
requires __::shared_ptr_compatible<T, U>
shared_ptr<T>::shared_ptr(U* const p, D d)
: p(p), rc(__::shared_pointer<U, D>::make(p, move(d)))
{
if constexpr (is_base_of_v<enable_shared_from_this<U>, U>) {
p->weak_this = *this;
}
}
template<typename T, typename... Args>
shared_ptr<T>
make_shared(Args&&... args)
@ -452,6 +506,9 @@ make_shared(Args&&... args)
shared_ptr<T> r;
r.p = &rc->t;
r.rc = rc.release();
if constexpr (is_base_of_v<enable_shared_from_this<T>, T>) {
r->weak_this = r;
}
return r;
}