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#pragma once
#include <util/generic/ptr.h>
#include <library/cpp/deprecated/atomic/atomic.h>
namespace NNeh {
//limited emulation shared_ptr/weak_ptr from boost lib.
//the main value means the weak_ptr functionality, else recommended use types from util/generic/ptr.h
//smart pointer counter shared between shared and weak ptrs.
class TSPCounted: public TThrRefBase {
public:
inline TSPCounted() noexcept
: C_(0)
{
}
inline void Inc() noexcept {
AtomicIncrement(C_);
}
//return false if C_ already 0, else increment and return true
inline bool TryInc() noexcept {
for (;;) {
intptr_t curVal(AtomicGet(C_));
if (!curVal) {
return false;
}
intptr_t newVal(curVal + 1);
if (AtomicCas(&C_, newVal, curVal)) {
return true;
}
}
}
inline intptr_t Dec() noexcept {
return AtomicDecrement(C_);
}
inline intptr_t Value() const noexcept {
return AtomicGet(C_);
}
private:
TAtomic C_;
};
typedef TIntrusivePtr<TSPCounted> TSPCountedRef;
class TWeakCount;
class TSPCount {
public:
TSPCount(TSPCounted* c = nullptr) noexcept
: C_(c)
{
}
inline void Swap(TSPCount& r) noexcept {
DoSwap(C_, r.C_);
}
inline size_t UseCount() const noexcept {
if (!C_) {
return 0;
}
return C_->Value();
}
inline bool operator!() const noexcept {
return !C_;
}
inline TSPCounted* GetCounted() const noexcept {
return C_.Get();
}
inline void Reset() noexcept {
if (!!C_) {
C_.Drop();
}
}
protected:
TIntrusivePtr<TSPCounted> C_;
};
class TSharedCount: public TSPCount {
public:
inline TSharedCount() noexcept {
}
/// @throws std::bad_alloc
inline explicit TSharedCount(const TSharedCount& r)
: TSPCount(r.C_.Get())
{
if (!!C_) {
(C_->Inc());
}
}
//'c' must exist and has already increased ref
inline explicit TSharedCount(TSPCounted* c) noexcept
: TSPCount(c)
{
}
public:
/// @throws std::bad_alloc
inline void Inc() {
if (!C_) {
TSPCountedRef(new TSPCounted()).Swap(C_);
}
C_->Inc();
}
inline bool TryInc() noexcept {
if (!C_) {
return false;
}
return C_->TryInc();
}
inline intptr_t Dec() noexcept {
if (!C_) {
Y_ASSERT(0);
return 0;
}
return C_->Dec();
}
void Drop() noexcept {
C_.Drop();
}
protected:
template <class Y>
friend class TSharedPtrB;
// 'c' MUST BE already incremented
void Assign(TSPCounted* c) noexcept {
TSPCountedRef(c).Swap(C_);
}
private:
TSharedCount& operator=(const TSharedCount&); //disable
};
class TWeakCount: public TSPCount {
public:
inline TWeakCount() noexcept {
}
inline explicit TWeakCount(const TWeakCount& r) noexcept
: TSPCount(r.GetCounted())
{
}
inline explicit TWeakCount(const TSharedCount& r) noexcept
: TSPCount(r.GetCounted())
{
}
private:
TWeakCount& operator=(const TWeakCount&); //disable
};
template <class T>
class TWeakPtrB;
template <class T>
class TSharedPtrB {
public:
inline TSharedPtrB() noexcept
: T_(nullptr)
{
}
/// @throws std::bad_alloc
inline TSharedPtrB(T* t)
: T_(nullptr)
{
if (t) {
THolder<T> h(t);
C_.Inc();
T_ = h.Release();
}
}
inline TSharedPtrB(const TSharedPtrB<T>& r) noexcept
: T_(r.T_)
, C_(r.C_)
{
Y_ASSERT((!!T_ && !!C_.UseCount()) || (!T_ && !C_.UseCount()));
}
inline TSharedPtrB(const TWeakPtrB<T>& r) noexcept
: T_(r.T_)
{
if (T_) {
TSPCounted* spc = r.C_.GetCounted();
if (spc && spc->TryInc()) {
C_.Assign(spc);
} else { //obsolete ptr
T_ = nullptr;
}
}
}
inline ~TSharedPtrB() {
Reset();
}
TSharedPtrB& operator=(const TSharedPtrB<T>& r) noexcept {
TSharedPtrB<T>(r).Swap(*this);
return *this;
}
TSharedPtrB& operator=(const TWeakPtrB<T>& r) noexcept {
TSharedPtrB<T>(r).Swap(*this);
return *this;
}
void Swap(TSharedPtrB<T>& r) noexcept {
DoSwap(T_, r.T_);
DoSwap(C_, r.C_);
Y_ASSERT((!!T_ && !!UseCount()) || (!T_ && !UseCount()));
}
inline bool operator!() const noexcept {
return !T_;
}
inline T* Get() noexcept {
return T_;
}
inline T* operator->() noexcept {
return T_;
}
inline T* operator->() const noexcept {
return T_;
}
inline T& operator*() noexcept {
return *T_;
}
inline T& operator*() const noexcept {
return *T_;
}
inline void Reset() noexcept {
if (T_) {
if (C_.Dec() == 0) {
delete T_;
}
T_ = nullptr;
C_.Drop();
}
}
inline size_t UseCount() const noexcept {
return C_.UseCount();
}
protected:
template <class Y>
friend class TWeakPtrB;
T* T_;
TSharedCount C_;
};
template <class T>
class TWeakPtrB {
public:
inline TWeakPtrB() noexcept
: T_(nullptr)
{
}
inline TWeakPtrB(const TWeakPtrB<T>& r) noexcept
: T_(r.T_)
, C_(r.C_)
{
}
inline TWeakPtrB(const TSharedPtrB<T>& r) noexcept
: T_(r.T_)
, C_(r.C_)
{
}
TWeakPtrB& operator=(const TWeakPtrB<T>& r) noexcept {
TWeakPtrB(r).Swap(*this);
return *this;
}
TWeakPtrB& operator=(const TSharedPtrB<T>& r) noexcept {
TWeakPtrB(r).Swap(*this);
return *this;
}
inline void Swap(TWeakPtrB<T>& r) noexcept {
DoSwap(T_, r.T_);
DoSwap(C_, r.C_);
}
inline void Reset() noexcept {
T_ = 0;
C_.Reset();
}
inline size_t UseCount() const noexcept {
return C_.UseCount();
}
protected:
template <class Y>
friend class TSharedPtrB;
T* T_;
TWeakCount C_;
};
}
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