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// Copyright 2016 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CORE_FXCRT_RETAIN_PTR_H_
#define CORE_FXCRT_RETAIN_PTR_H_
#include <functional>
#include <memory>
#include <utility>
#include "core/fxcrt/fx_system.h"
namespace fxcrt {
// Used with std::unique_ptr to Release() objects that can't be deleted.
template <class T>
struct ReleaseDeleter {
inline void operator()(T* ptr) const { ptr->Release(); }
};
// Analogous to base's scoped_refptr.
template <class T>
class RetainPtr {
public:
explicit RetainPtr(T* pObj) : m_pObj(pObj) {
if (m_pObj)
m_pObj->Retain();
}
RetainPtr() {}
RetainPtr(const RetainPtr& that) : RetainPtr(that.Get()) {}
RetainPtr(RetainPtr&& that) noexcept { Swap(that); }
// Deliberately implicit to allow returning nullptrs.
// NOLINTNEXTLINE(runtime/explicit)
RetainPtr(std::nullptr_t ptr) {}
template <class U>
RetainPtr(const RetainPtr<U>& that) : RetainPtr(that.Get()) {}
template <class U>
RetainPtr<U> As() const {
return RetainPtr<U>(static_cast<U*>(Get()));
}
void Reset(T* obj = nullptr) {
if (obj)
obj->Retain();
m_pObj.reset(obj);
}
T* Get() const { return m_pObj.get(); }
void Swap(RetainPtr& that) { m_pObj.swap(that.m_pObj); }
// Useful for passing notion of object ownership across a C API.
T* Leak() { return m_pObj.release(); }
void Unleak(T* ptr) { m_pObj.reset(ptr); }
RetainPtr& operator=(const RetainPtr& that) {
if (*this != that)
Reset(that.Get());
return *this;
}
RetainPtr& operator=(RetainPtr&& that) {
m_pObj.reset(that.Leak());
return *this;
}
bool operator==(const RetainPtr& that) const { return Get() == that.Get(); }
bool operator!=(const RetainPtr& that) const { return !(*this == that); }
bool operator<(const RetainPtr& that) const {
return std::less<T*>()(Get(), that.Get());
}
explicit operator bool() const { return !!m_pObj; }
T& operator*() const { return *m_pObj.get(); }
T* operator->() const { return m_pObj.get(); }
private:
std::unique_ptr<T, ReleaseDeleter<T>> m_pObj;
};
// Trivial implementation - internal ref count with virtual destructor.
class Retainable {
public:
bool HasOneRef() const { return m_nRefCount == 1; }
protected:
virtual ~Retainable() {}
private:
template <typename U>
friend struct ReleaseDeleter;
template <typename U>
friend class RetainPtr;
void Retain() { ++m_nRefCount; }
void Release() {
ASSERT(m_nRefCount > 0);
if (--m_nRefCount == 0)
delete this;
}
intptr_t m_nRefCount = 0;
};
} // namespace fxcrt
using fxcrt::ReleaseDeleter;
using fxcrt::RetainPtr;
using fxcrt::Retainable;
namespace pdfium {
// Helper to make a RetainPtr along the lines of std::make_unique<>(),
// or pdfium::MakeUnique<>(). Arguments are forwarded to T's constructor.
// Classes managed by RetainPtr should have protected (or private)
// constructors, and should friend this function.
template <typename T, typename... Args>
RetainPtr<T> MakeRetain(Args&&... args) {
return RetainPtr<T>(new T(std::forward<Args>(args)...));
}
} // namespace pdfium
#endif // CORE_FXCRT_RETAIN_PTR_H_
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