mirror of https://github.com/axmolengine/axmol.git
121 lines
3.3 KiB
C++
121 lines
3.3 KiB
C++
#ifndef INTRUSIVE_PTR_H
|
|
#define INTRUSIVE_PTR_H
|
|
|
|
#include <utility>
|
|
|
|
#include "atomic.h"
|
|
#include "opthelpers.h"
|
|
|
|
|
|
namespace al {
|
|
|
|
template<typename T>
|
|
class intrusive_ref {
|
|
RefCount mRef{1u};
|
|
|
|
public:
|
|
unsigned int add_ref() noexcept { return IncrementRef(mRef); }
|
|
unsigned int dec_ref() noexcept
|
|
{
|
|
auto ref = DecrementRef(mRef);
|
|
if(ref == 0) UNLIKELY
|
|
delete static_cast<T*>(this);
|
|
return ref;
|
|
}
|
|
|
|
/**
|
|
* Release only if doing so would not bring the object to 0 references and
|
|
* delete it. Returns false if the object could not be released.
|
|
*
|
|
* NOTE: The caller is responsible for handling a failed release, as it
|
|
* means the object has no other references and needs to be be deleted
|
|
* somehow.
|
|
*/
|
|
bool releaseIfNoDelete() noexcept
|
|
{
|
|
auto val = mRef.load(std::memory_order_acquire);
|
|
while(val > 1 && !mRef.compare_exchange_strong(val, val-1, std::memory_order_acq_rel))
|
|
{
|
|
/* val was updated with the current value on failure, so just try
|
|
* again.
|
|
*/
|
|
}
|
|
|
|
return val >= 2;
|
|
}
|
|
};
|
|
|
|
|
|
template<typename T>
|
|
class intrusive_ptr {
|
|
T *mPtr{nullptr};
|
|
|
|
public:
|
|
intrusive_ptr() noexcept = default;
|
|
intrusive_ptr(const intrusive_ptr &rhs) noexcept : mPtr{rhs.mPtr}
|
|
{ if(mPtr) mPtr->add_ref(); }
|
|
intrusive_ptr(intrusive_ptr&& rhs) noexcept : mPtr{rhs.mPtr}
|
|
{ rhs.mPtr = nullptr; }
|
|
intrusive_ptr(std::nullptr_t) noexcept { }
|
|
explicit intrusive_ptr(T *ptr) noexcept : mPtr{ptr} { }
|
|
~intrusive_ptr() { if(mPtr) mPtr->dec_ref(); }
|
|
|
|
intrusive_ptr& operator=(const intrusive_ptr &rhs) noexcept
|
|
{
|
|
static_assert(noexcept(std::declval<T*>()->dec_ref()), "dec_ref must be noexcept");
|
|
|
|
if(rhs.mPtr) rhs.mPtr->add_ref();
|
|
if(mPtr) mPtr->dec_ref();
|
|
mPtr = rhs.mPtr;
|
|
return *this;
|
|
}
|
|
intrusive_ptr& operator=(intrusive_ptr&& rhs) noexcept
|
|
{
|
|
if(&rhs != this) LIKELY
|
|
{
|
|
if(mPtr) mPtr->dec_ref();
|
|
mPtr = std::exchange(rhs.mPtr, nullptr);
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
explicit operator bool() const noexcept { return mPtr != nullptr; }
|
|
|
|
T& operator*() const noexcept { return *mPtr; }
|
|
T* operator->() const noexcept { return mPtr; }
|
|
T* get() const noexcept { return mPtr; }
|
|
|
|
void reset(T *ptr=nullptr) noexcept
|
|
{
|
|
if(mPtr)
|
|
mPtr->dec_ref();
|
|
mPtr = ptr;
|
|
}
|
|
|
|
T* release() noexcept { return std::exchange(mPtr, nullptr); }
|
|
|
|
void swap(intrusive_ptr &rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
|
|
void swap(intrusive_ptr&& rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
|
|
};
|
|
|
|
#define AL_DECL_OP(op) \
|
|
template<typename T> \
|
|
inline bool operator op(const intrusive_ptr<T> &lhs, const T *rhs) noexcept \
|
|
{ return lhs.get() op rhs; } \
|
|
template<typename T> \
|
|
inline bool operator op(const T *lhs, const intrusive_ptr<T> &rhs) noexcept \
|
|
{ return lhs op rhs.get(); }
|
|
|
|
AL_DECL_OP(==)
|
|
AL_DECL_OP(!=)
|
|
AL_DECL_OP(<=)
|
|
AL_DECL_OP(>=)
|
|
AL_DECL_OP(<)
|
|
AL_DECL_OP(>)
|
|
|
|
#undef AL_DECL_OP
|
|
|
|
} // namespace al
|
|
|
|
#endif /* INTRUSIVE_PTR_H */
|