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// Scintilla source code edit control
/** @file WinTypes.h
** Implement safe release of COM objects and access to functions in DLLs.
** Header contains all implementation - there is no .cxx file.
**/
// Copyright 2020-2021 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.
#ifndef WINTYPES_H
#define WINTYPES_H
namespace Scintilla::Internal {
// Release an IUnknown* and set to nullptr.
// While IUnknown::Release must be noexcept, it isn't marked as such so produces
// warnings which are avoided by the catch.
template <class T>
inline void ReleaseUnknown(T *&ppUnknown) noexcept {
if (ppUnknown) {
try {
ppUnknown->Release();
} catch (...) {
// Never occurs
}
ppUnknown = nullptr;
}
}
struct UnknownReleaser {
// Called by unique_ptr to destroy/free the resource
template <class T>
void operator()(T *pUnknown) noexcept {
try {
pUnknown->Release();
} catch (...) {
// IUnknown::Release must not throw, ignore if it does.
}
}
};
// Wrap COM IUnknown::QueryInterface to produce std::unique_ptr objects to help
// ensure safe reference counting.
template<typename T>
inline HRESULT UniquePtrFromQI(IUnknown *source, REFIID riid, std::unique_ptr<T, UnknownReleaser> &destination) noexcept {
T *ptr{};
HRESULT hr = E_FAIL;
try {
hr = source->QueryInterface(riid, reinterpret_cast<void **>(&ptr));
} catch (...) {
// Shouldn't have exceptions from QueryInterface but not marked noexcept
}
if (SUCCEEDED(hr)) {
destination.reset(ptr);
} else {
destination.reset();
}
return hr;
}
/// Find a function in a DLL and convert to a function pointer.
/// This avoids undefined and conditionally defined behaviour.
template<typename T>
inline T DLLFunction(HMODULE hModule, LPCSTR lpProcName) noexcept {
if (!hModule) {
return nullptr;
}
FARPROC function = ::GetProcAddress(hModule, lpProcName);
static_assert(sizeof(T) == sizeof(function));
T fp {};
memcpy(&fp, &function, sizeof(T));
return fp;
}
}
#endif
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