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58 lines
1.4 KiB
C++
58 lines
1.4 KiB
C++
// This file is part of Desktop App Toolkit,
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// a set of libraries for developing nice desktop applications.
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//
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// For license and copyright information please follow this link:
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// https://github.com/desktop-app/legal/blob/master/LEGAL
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//
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#pragma once
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#include <optional>
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namespace base {
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template <typename Type>
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struct optional_wrap_once {
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using type = std::optional<Type>;
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};
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template <typename Type>
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struct optional_wrap_once<std::optional<Type>> {
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using type = std::optional<Type>;
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};
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template <typename Type>
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using optional_wrap_once_t = typename optional_wrap_once<std::decay_t<Type>>::type;
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template <typename Type>
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struct optional_chain_result {
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using type = optional_wrap_once_t<Type>;
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};
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template <>
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struct optional_chain_result<void> {
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using type = bool;
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};
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template <typename Type>
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using optional_chain_result_t = typename optional_chain_result<Type>::type;
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template <typename Type>
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optional_wrap_once_t<Type> make_optional(Type &&value) {
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return optional_wrap_once_t<Type> { std::forward<Type>(value) };
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}
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} // namespace base
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template <typename Type, typename Method>
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inline auto operator|(const std::optional<Type> &value, Method method)
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-> base::optional_chain_result_t<decltype(method(*value))> {
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if constexpr (std::is_same_v<decltype(method(*value)), void>) {
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return value ? (method(*value), true) : false;
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} else {
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return value
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? base::optional_chain_result_t<decltype(method(*value))>(
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method(*value))
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: std::nullopt;
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}
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}
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