146 lines
3.8 KiB
C++
146 lines
3.8 KiB
C++
/*
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This file is part of Telegram Desktop,
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the official desktop application for the Telegram messaging service.
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For license and copyright information please follow this link:
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https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
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*/
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#pragma once
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#include "base/build_config.h"
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#include <tuple>
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namespace rpl {
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namespace details {
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template <typename Arg>
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const Arg &const_ref_val() noexcept;
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template <typename Arg>
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Arg &lvalue_ref_val() noexcept;
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using false_t = char;
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struct true_t {
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false_t data[2];
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};
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static_assert(sizeof(false_t) != sizeof(true_t), "I can't work :(");
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template <
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typename Method,
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typename ...Args,
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typename = decltype(std::declval<Method>()(
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std::declval<Args>()...))>
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true_t test_callable_plain(Method &&, Args &&...) noexcept;
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false_t test_callable_plain(...) noexcept;
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template <typename Method, typename ...Args>
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struct is_callable_plain
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: std::bool_constant<(
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sizeof(test_callable_plain(
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std::declval<Method>(),
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std::declval<Args>()...
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)) == sizeof(true_t))> {
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};
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template <typename Method, typename ...Args>
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constexpr bool is_callable_plain_v = is_callable_plain<Method, Args...>::value;
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template <
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typename Method,
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typename ...Types,
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typename = decltype(std::declval<Method>()(
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std::declval<Types>()...))>
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true_t test_callable_tuple(
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Method &&,
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std::tuple<Types...> &&) noexcept;
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template <
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typename Method,
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typename ...Types,
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typename = decltype(std::declval<Method>()(
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const_ref_val<Types>()...))>
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true_t test_callable_tuple(
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Method &&,
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const std::tuple<Types...> &) noexcept;
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false_t test_callable_tuple(...) noexcept;
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template <typename Method, typename Arg>
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constexpr bool is_callable_tuple_v = (sizeof(test_callable_tuple(
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std::declval<Method>(),
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std::declval<Arg>())) == sizeof(true_t));
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template <typename Method, typename Arg>
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struct is_callable_tuple
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: std::bool_constant<
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is_callable_tuple_v<Method, Arg>> {
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};
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template <typename Method, typename ...Args>
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struct is_callable;
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template <typename Method>
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struct is_callable<Method>
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: std::bool_constant<
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is_callable_plain_v<Method>> {
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};
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template <typename Method, typename Arg>
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struct is_callable<Method, Arg>
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: std::bool_constant<
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is_callable_plain_v<Method, Arg> ||
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is_callable_tuple_v<Method, Arg> ||
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is_callable_plain_v<Method>> {
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};
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template <typename Method, typename ...Args>
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constexpr bool is_callable_v = is_callable<Method, Args...>::value;
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template <typename Method, typename Arg>
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inline decltype(auto) callable_invoke(Method &&method, Arg &&arg) {
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if constexpr (is_callable_plain_v<Method, Arg>) {
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return std::forward<Method>(method)(std::forward<Arg>(arg));
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} else if constexpr (is_callable_tuple_v<Method, Arg>) {
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return std::apply(
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std::forward<Method>(method),
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std::forward<Arg>(arg));
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} else if constexpr (is_callable_v<Method>) {
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return std::forward<Method>(method)();
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} else {
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static_assert(false_(method, arg), "Bad callable_invoke() call.");
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}
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}
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template <typename Method, typename Arg>
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using callable_result = decltype(callable_invoke(
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std::declval<Method>(),
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std::declval<Arg>()));
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template <
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typename Method,
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typename Arg,
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typename = decltype(std::declval<Method>()(
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const_ref_val<std::decay_t<Arg>>()))>
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true_t test_allows_const_ref(Method &&, Arg &&) noexcept;
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false_t test_allows_const_ref(...) noexcept;
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template <typename Method, typename Arg>
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constexpr bool allows_const_ref_v = (sizeof(test_allows_const_ref(
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std::declval<Method>(),
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std::declval<Arg>())) == sizeof(true_t));
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template <typename Method, typename Arg>
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inline decltype(auto) const_ref_call_invoke(
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Method &&method,
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const Arg &arg) {
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if constexpr (allows_const_ref_v<Method, Arg>) {
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return callable_invoke(std::forward<Method>(method), arg);
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} else {
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auto copy = arg;
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return callable_invoke(
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std::forward<Method>(method),
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std::move(copy));
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}
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}
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} // namespace details
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} // namespace rpl
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