common/comptr.h

   1 #ifndef COMMON_COMPTR_H
   2 #define COMMON_COMPTR_H
   3
   4 #include <cstddef>
   5 #include <memory>
   6 #include <type_traits>
   7 #include <utility>
   8 #include <variant>
   9
  10 #define WIN32_LEAN_AND_MEAN
  11 #include <windows.h>
  12 #include <objbase.h>
  13
  14 struct ComWrapper {
  15     HRESULT mStatus{};
  16
  17     ComWrapper(void *reserved, DWORD coinit)
  18         : mStatus{CoInitializeEx(reserved, coinit)}
  19     { }
  20     ComWrapper(DWORD coinit=COINIT_APARTMENTTHREADED)
  21         : mStatus{CoInitializeEx(nullptr, coinit)}
  22     { }
  23     ComWrapper(ComWrapper&& rhs) { mStatus = std::exchange(rhs.mStatus, E_FAIL); }
  24     ComWrapper(const ComWrapper&) = delete;
  25     ~ComWrapper() { if(SUCCEEDED(mStatus)) CoUninitialize(); }
  26
  27     ComWrapper& operator=(ComWrapper&& rhs)
  28     {
  29         if(SUCCEEDED(mStatus))
  30             CoUninitialize();
  31         mStatus = std::exchange(rhs.mStatus, E_FAIL);
  32         return *this;
  33     }
  34     ComWrapper& operator=(const ComWrapper&) = delete;
  35
  36     [[nodiscard]]
  37     HRESULT status() const noexcept { return mStatus; }
  38     explicit operator bool() const noexcept { return SUCCEEDED(status()); }
  39
  40     void uninit()
  41     {
  42         if(SUCCEEDED(mStatus))
  43             CoUninitialize();
  44         mStatus = E_FAIL;
  45     }
  46 };
  47
  48
  49 template<typename T>
  50 struct ComPtr {
  51     using element_type = T;
  52
  53     static constexpr bool RefIsNoexcept{noexcept(std::declval<T&>().AddRef())
  54         && noexcept(std::declval<T&>().Release())};
  55
  56     ComPtr() noexcept = default;
  57     ComPtr(const ComPtr &rhs) noexcept(RefIsNoexcept) : mPtr{rhs.mPtr}
  58     { if(mPtr) mPtr->AddRef(); }
  59     ComPtr(ComPtr&& rhs) noexcept : mPtr{rhs.mPtr} { rhs.mPtr = nullptr; }
  60     ComPtr(std::nullptr_t) noexcept { }
  61     explicit ComPtr(T *ptr) noexcept : mPtr{ptr} { }
  62     ~ComPtr() { if(mPtr) mPtr->Release(); }
  63
  64     /* NOLINTNEXTLINE(bugprone-unhandled-self-assignment) Yes it is. */
  65     ComPtr& operator=(const ComPtr &rhs) noexcept(RefIsNoexcept)
  66     {
  67         if constexpr(RefIsNoexcept)
  68         {
  69             if(rhs.mPtr) rhs.mPtr->AddRef();
  70             if(mPtr) mPtr->Release();
  71             mPtr = rhs.mPtr;
  72             return *this;
  73         }
  74         else
  75         {
  76             ComPtr tmp{rhs};
  77             if(mPtr) mPtr->Release();
  78             mPtr = tmp.release();
  79             return *this;
  80         }
  81     }
  82     ComPtr& operator=(ComPtr&& rhs) noexcept(RefIsNoexcept)
  83     {
  84         if(&rhs != this)
  85         {
  86             if(mPtr) mPtr->Release();
  87             mPtr = std::exchange(rhs.mPtr, nullptr);
  88         }
  89         return *this;
  90     }
  91
  92     void reset(T *ptr=nullptr) noexcept(RefIsNoexcept)
  93     {
  94         if(mPtr) mPtr->Release();
  95         mPtr = ptr;
  96     }
  97
  98     explicit operator bool() const noexcept { return mPtr != nullptr; }
  99
 100     T& operator*() const noexcept { return *mPtr; }
 101     T* operator->() const noexcept { return mPtr; }
 102     T* get() const noexcept { return mPtr; }
 103
 104     T* release() noexcept { return std::exchange(mPtr, nullptr); }
 105
 106     void swap(ComPtr &rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
 107     void swap(ComPtr&& rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
 108
 109 private:
 110     T *mPtr{nullptr};
 111 };
 112
 113 #endif