| // Copyright 2016 The PDFium Authors |
| // 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 <stdint.h> |
| |
| #include <functional> |
| #include <memory> |
| #include <type_traits> |
| #include <utility> |
| |
| #include "core/fxcrt/check.h" |
| #include "core/fxcrt/compiler_specific.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 TRIVIAL_ABI RetainPtr { |
| public: |
| RetainPtr() noexcept = default; |
| |
| // Deliberately implicit to allow returning nullptrs. |
| // NOLINTNEXTLINE(runtime/explicit) |
| RetainPtr(std::nullptr_t ptr) {} |
| |
| explicit RetainPtr(T* pObj) noexcept : m_pObj(pObj) { |
| if (m_pObj) |
| m_pObj->Retain(); |
| } |
| |
| // Copy-construct a RetainPtr. |
| // Required in addition to copy conversion constructor below. |
| RetainPtr(const RetainPtr& that) noexcept : RetainPtr(that.Get()) {} |
| |
| // Move-construct a RetainPtr. After construction, |that| will be NULL. |
| // Required in addition to move conversion constructor below. |
| RetainPtr(RetainPtr&& that) noexcept { Unleak(that.Leak()); } |
| |
| // Copy conversion constructor. |
| template <class U, |
| typename = typename std::enable_if< |
| std::is_convertible<U*, T*>::value>::type> |
| RetainPtr(const RetainPtr<U>& that) : RetainPtr(that.Get()) {} |
| |
| // Move-conversion constructor. |
| template <class U, |
| typename = typename std::enable_if< |
| std::is_convertible<U*, T*>::value>::type> |
| RetainPtr(RetainPtr<U>&& that) noexcept { |
| Unleak(that.Leak()); |
| } |
| |
| // Assign a RetainPtr from nullptr; |
| RetainPtr& operator=(std::nullptr_t) noexcept { |
| Reset(); |
| return *this; |
| } |
| |
| // Copy-assign a RetainPtr. |
| // Required in addition to copy conversion assignment below. |
| RetainPtr& operator=(const RetainPtr& that) { |
| if (*this != that) |
| Reset(that.Get()); |
| return *this; |
| } |
| |
| // Move-assign a RetainPtr. After assignment, |that| will be NULL. |
| // Required in addition to move conversion assignment below. |
| RetainPtr& operator=(RetainPtr&& that) noexcept { |
| Unleak(that.Leak()); |
| return *this; |
| } |
| |
| // Copy-convert assign a RetainPtr. |
| template <class U, |
| typename = typename std::enable_if< |
| std::is_convertible<U*, T*>::value>::type> |
| RetainPtr& operator=(const RetainPtr<U>& that) { |
| if (*this != that) |
| Reset(that.Get()); |
| return *this; |
| } |
| |
| // Move-convert assign a RetainPtr. After assignment, |that| will be NULL. |
| template <class U, |
| typename = typename std::enable_if< |
| std::is_convertible<U*, T*>::value>::type> |
| RetainPtr& operator=(RetainPtr<U>&& that) noexcept { |
| Unleak(that.Leak()); |
| return *this; |
| } |
| |
| ~RetainPtr() = default; |
| |
| template <class U> |
| U* AsRaw() const { |
| return static_cast<U*>(Get()); |
| } |
| |
| template <class U> |
| RetainPtr<U> As() const { |
| return RetainPtr<U>(AsRaw<U>()); |
| } |
| |
| void Reset(T* obj = nullptr) { |
| if (obj) |
| obj->Retain(); |
| m_pObj.reset(obj); |
| } |
| |
| operator T*() const noexcept { return Get(); } |
| T* Get() const noexcept { 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); } |
| |
| bool operator==(const RetainPtr& that) const { return Get() == that.Get(); } |
| bool operator!=(const RetainPtr& that) const { return !(*this == that); } |
| |
| template <typename U> |
| bool operator==(const U& that) const { |
| return Get() == that; |
| } |
| |
| template <typename U> |
| bool operator!=(const U& 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; } |
| 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: |
| Retainable() = default; |
| |
| bool HasOneRef() const { return m_nRefCount == 1; } |
| |
| protected: |
| virtual ~Retainable() = default; |
| |
| private: |
| template <typename U> |
| friend struct ReleaseDeleter; |
| |
| template <typename U> |
| friend class RetainPtr; |
| |
| Retainable(const Retainable& that) = delete; |
| Retainable& operator=(const Retainable& that) = delete; |
| |
| // These need to be const methods operating on a mutable member so that |
| // RetainPtr<const T> can be used for an object that is otherwise const |
| // apart from the internal ref-counting. |
| void Retain() const { |
| ++m_nRefCount; |
| CHECK(m_nRefCount > 0); |
| } |
| void Release() const { |
| CHECK(m_nRefCount > 0); |
| if (--m_nRefCount == 0) |
| delete this; |
| } |
| |
| mutable uintptr_t m_nRefCount = 0; |
| static_assert(std::is_unsigned<decltype(m_nRefCount)>::value, |
| "m_nRefCount must be an unsigned type for overflow check" |
| "to work properly in Retain()"); |
| }; |
| |
| } // namespace fxcrt |
| |
| using fxcrt::ReleaseDeleter; |
| using fxcrt::Retainable; |
| using fxcrt::RetainPtr; |
| |
| namespace pdfium { |
| |
| // Helper to make a RetainPtr along the lines of std::make_unique<>(). |
| // 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)...)); |
| } |
| |
| // Type-deducing wrapper to make a RetainPtr from an ordinary pointer, |
| // since equivalent constructor is explicit. |
| template <typename T> |
| RetainPtr<T> WrapRetain(T* that) { |
| return RetainPtr<T>(that); |
| } |
| |
| } // namespace pdfium |
| |
| // Macro to allow construction via MakeRetain<>() only, when used |
| // with a private constructor in a class. |
| #define CONSTRUCT_VIA_MAKE_RETAIN \ |
| template <typename T, typename... Args> \ |
| friend RetainPtr<T> pdfium::MakeRetain(Args&&... args) |
| |
| #endif // CORE_FXCRT_RETAIN_PTR_H_ |