common/comptr.h

   1 #ifndef COMMON_COMPTR_H
   2 #define COMMON_COMPTR_H
   3
   4 #include <cstddef>
   5 #include <utility>
   6
   7 #include "opthelpers.h"
   8
   9
  10 template<typename T>
  11 class ComPtr {
  12     T *mPtr{nullptr};
  13
  14 public:
  15     ComPtr() noexcept = default;
  16     ComPtr(const ComPtr &rhs) : mPtr{rhs.mPtr} { if(mPtr) mPtr->AddRef(); }
  17     ComPtr(ComPtr&& rhs) noexcept : mPtr{rhs.mPtr} { rhs.mPtr = nullptr; }
  18     ComPtr(std::nullptr_t) noexcept { }
  19     explicit ComPtr(T *ptr) noexcept : mPtr{ptr} { }
  20     ~ComPtr() { if(mPtr) mPtr->Release(); }
  21
  22     ComPtr& operator=(const ComPtr &rhs)
  23     {
  24         if(!rhs.mPtr)
  25         {
  26             if(mPtr)
  27                 mPtr->Release();
  28             mPtr = nullptr;
  29         }
  30         else
  31         {
  32             rhs.mPtr->AddRef();
  33             try {
  34                 if(mPtr)
  35                     mPtr->Release();
  36                 mPtr = rhs.mPtr;
  37             }
  38             catch(...) {
  39                 rhs.mPtr->Release();
  40                 throw;
  41             }
  42         }
  43         return *this;
  44     }
  45     ComPtr& operator=(ComPtr&& rhs)
  46     {
  47         if(&rhs != this) LIKELY
  48         {
  49             if(mPtr) mPtr->Release();
  50             mPtr = std::exchange(rhs.mPtr, nullptr);
  51         }
  52         return *this;
  53     }
  54
  55     explicit operator bool() const noexcept { return mPtr != nullptr; }
  56
  57     T& operator*() const noexcept { return *mPtr; }
  58     T* operator->() const noexcept { return mPtr; }
  59     T* get() const noexcept { return mPtr; }
  60     T** getPtr() noexcept { return &mPtr; }
  61
  62     T* release() noexcept { return std::exchange(mPtr, nullptr); }
  63
  64     void swap(ComPtr &rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
  65     void swap(ComPtr&& rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
  66 };
  67
  68 #endif