Types.h

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/*
 * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef Types_h__
#define Types_h__
 
#include <type_traits>
 
namespace Trinity
{
 // end "iterator" tag for find_type_if
 struct find_type_end;
 
 template<template<typename...> typename Check, typename... Ts>
 struct find_type_if;
 
 template<template<typename...> typename Check>
 struct find_type_if<Check>
 {
 using type = find_type_end;
 };
 
 template<template<typename...> typename Check, typename T1, typename... Ts>
 struct find_type_if<Check, T1, Ts...> : std::conditional_t<Check<T1>::value, std::type_identity<T1>, find_type_if<Check, Ts...>>
 {
 };
 
 /*
 Utility to find a type matching predicate (Check) in a given type list (Ts)
 Evaluates to first type matching predicate or find_type_end
 Check must be a type that contains static bool ::value, _v aliases don't work
 
 template<typename... Ts>
 struct Example
 {
 using TupleArg = Trinity::find_type_if_t<Trinity::is_tuple, Ts...>;
 
 bool HasTuple()
 {
 return !std::is_same_v<TupleArg, Trinity::find_type_end>;
 }
 };
 
 Example<int, std::string, std::tuple<int, int, int>, char> example;
 example.HasTuple() == true; // TupleArg is std::tuple<int, int, int>
 
 Example<int, std::string, char> example2;
 example2.HasTuple() == false; // TupleArg is Trinity::find_type_end
 */
 template<template<typename...> typename Check, typename... Ts>
 using find_type_if_t = typename find_type_if<Check, Ts...>::type;
 
 template <typename T>
 struct dependant_false { static constexpr bool value = false; };
 
 template <typename T>
 constexpr bool dependant_false_v = dependant_false<T>::value;
}
 
#endif // Types_h__