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/*
* Copyright 2020-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_WIN32_COMPTR_HXX
#define MPD_WIN32_COMPTR_HXX
#include "win32/HResult.hxx"
#include <cstddef>
#include <objbase.h>
#include <utility>
#include <windows.h>
// RAII for Object in Microsoft Component Object Model(COM)
// https://docs.microsoft.com/zh-tw/windows/win32/api/_com/
template <typename T>
class ComPtr {
public:
using pointer = T *;
using reference = T &;
using element_type = T;
constexpr ComPtr() noexcept : ptr(nullptr) {}
constexpr ComPtr(std::nullptr_t) noexcept : ptr(nullptr) {}
explicit constexpr ComPtr(pointer p) noexcept : ptr(p) {}
ComPtr(const ComPtr &u) noexcept : ptr(u.ptr) {
if (ptr) {
ptr->AddRef();
}
}
constexpr ComPtr(ComPtr &&u) noexcept : ptr(std::exchange(u.ptr, nullptr)) {}
ComPtr &operator=(const ComPtr &r) noexcept {
reset();
ptr = r.ptr;
if (ptr) {
ptr->AddRef();
}
return *this;
}
constexpr ComPtr &operator=(ComPtr &&r) noexcept {
std::swap(ptr, r.ptr);
return *this;
}
ComPtr &operator=(std::nullptr_t) noexcept {
reset();
return *this;
}
~ComPtr() noexcept { reset(); }
pointer release() noexcept { return std::exchange(ptr, nullptr); }
void reset() noexcept {
if (ptr) {
release()->Release();
}
}
void swap(ComPtr &other) noexcept { std::swap(ptr, other.ptr); }
pointer get() const noexcept { return ptr; }
explicit operator bool() const noexcept { return ptr; }
reference operator*() const noexcept { return *ptr; }
pointer operator->() const noexcept { return ptr; }
void CoCreateInstance(REFCLSID class_id, LPUNKNOWN unknown_outer = nullptr,
DWORD class_context = CLSCTX_ALL) {
HRESULT result =
::CoCreateInstance(class_id, unknown_outer, class_context,
__uuidof(T), reinterpret_cast<void **>(&ptr));
if (FAILED(result)) {
throw FormatHResultError(result, "Unable to create instance");
}
}
T **Address() noexcept {
reset();
return &ptr;
}
template <typename U = void>
U **AddressCast() noexcept {
reset();
return reinterpret_cast<U **>(&ptr);
}
template <typename U = void>
U *Cast() noexcept {
return reinterpret_cast<U *>(ptr);
}
private:
pointer ptr;
};
namespace std {
template <typename T>
void swap(ComPtr<T> &lhs, ComPtr<T> &rhs) noexcept {
lhs.swap(rhs);
}
} // namespace std
#endif
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