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Telegram/lib_crl/crl/winapi/crl_winapi_dll.h

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+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#pragma once
+
+#include <crl/common/crl_common_config.h>
+
+#ifdef CRL_USE_WINAPI
+
+#include <exception>
+#include <crl/winapi/crl_winapi_windows_h.h>
+
+namespace crl::details {
+
+class dll {
+public:
+	enum class own_policy {
+		owner,
+		load_and_leak,
+		use_existing,
+	};
+	dll(LPCWSTR library, own_policy policy)
+	: _handle((policy == own_policy::use_existing)
+		? GetModuleHandle(library)
+		: LoadLibrary(library))
+	, _policy(policy) {
+	}
+
+	template <typename Function>
+	bool try_load(Function &function, const char *name) const {
+		if (!_handle) {
+			return false;
+		}
+		function = reinterpret_cast<Function>(GetProcAddress(_handle, name));
+		return (function != nullptr);
+	}
+
+	template <typename Function>
+	void load(Function &function, const char *name) const {
+		if (!try_load(function, name)) {
+			Failed();
+		}
+	}
+
+	~dll() {
+		if (_handle && _policy == own_policy::owner) {
+			FreeLibrary(_handle);
+		}
+	}
+
+private:
+	[[noreturn]] static void Failed() {
+		std::terminate();
+	}
+
+	HMODULE _handle = nullptr;
+	own_policy _policy = own_policy::use_existing;
+
+};
+
+} // namespace crl::details
+
+#endif // CRL_USE_WINAPI