94 lines
2.6 KiB
C++
94 lines
2.6 KiB
C++
#pragma once
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/*
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* Copyright (C) 2024 Brett Terpstra
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef BLT_META_H
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#define BLT_META_H
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#include <blt/std/types.h>
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#include <utility>
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#include <type_traits>
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#include <ostream>
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namespace blt::meta
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{
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template<typename IFirst, typename... IArgs>
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struct arg_helper
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{
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using First = IFirst;
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using Next = arg_helper<IArgs...>;
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};
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template<>
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struct arg_helper<void>
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{
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using First = void;
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using Next = void;
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};
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template<typename TheLambda, typename>
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struct lambda_helper
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{
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using Lambda = TheLambda;
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};
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template<typename TheLambda, typename IReturn, typename IClass, typename... LArgs>
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struct lambda_helper<TheLambda, IReturn (IClass::*)(LArgs...) const>
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{
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using Lambda = TheLambda;
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using Return = IReturn;
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using Class = IClass;
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using Args = arg_helper<LArgs...>;
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template<typename T>
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explicit lambda_helper(T)
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{}
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lambda_helper() = default;
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};
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template<typename Lambda>
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lambda_helper(Lambda) -> lambda_helper<Lambda, decltype(&Lambda::operator())>;
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// https://stackoverflow.com/questions/66397071/is-it-possible-to-check-if-overloaded-operator-for-type-or-class-exists
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template<class T>
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class is_streamable
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{
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private:
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template<typename Subs>
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static auto test(int) -> decltype(std::declval<std::ostream&>() << std::declval<Subs>(), std::true_type())
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{
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return std::declval<std::true_type>();
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}
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template<typename>
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static auto test(...) -> std::false_type
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{
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return std::declval<std::false_type>();
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}
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public:
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static constexpr bool value = decltype(test<T>(0))::value;
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};
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template<class T>
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inline constexpr bool is_streamable_v = is_streamable<T>::value;
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}
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#endif //BLT_GP_META_H
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