/**
	This file is a part of rexy's general purpose library
	Copyright (C) 2020 rexy712

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published by
	the Free Software Foundation, either version 3 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 Affero General Public License for more details.

	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef REXY_DETAIL_UTIL_HPP
#define REXY_DETAIL_UTIL_HPP

#include <cstddef> //size_t

namespace rexy::detail{
	namespace{
		//including <algorithm> causes long compile times. so just make my own max instead
		template<class T>
		constexpr const T& max(const T& a, const T& b){
			return (a < b) ? b : a;
		}
		template<class T>
		constexpr const T& min(const T& a, const T& b){
			return (a > b) ? b : a;
		}

		constexpr size_t cx_strlen(const char* c){
			size_t i = 0;
			for(;c[i];++i);
			return i;
		}
		constexpr int cx_strcmp(const char* l, const char* r){
			using uchar = unsigned char;
			for(;*l == *r && *l;++l, ++r);
			return (uchar{*l}) - (uchar{*r});
		}
	} //anonymous namespace
} //namespace detail

//std::swap and std::exchange aren't constexpr until c++20
#if __cplusplus > 201703L
		#include <utility>
		#define rexy_cx_swap(...) std::swap(__VA_ARGS__)
		#define rexy_cx_exchange(...) std::exchange(__VA_ARGS__)
#else
	#include <type_traits>
	namespace rexy::detail{
		namespace{
			template<class T>
			constexpr void cx_swap(T& a, T& b)noexcept(std::is_nothrow_move_constructible<T>::value &&
			                                           std::is_nothrow_move_assignable<T>::value)
			{
				T tmp = std::move(a);
				a = std::move(b);
				b = std::move(tmp);
			}
			template<class T, class U = T>
			constexpr T cx_exchange(T& t, U&& u){
				T old = std::move(t);
				t = std::forward<U>(u);
				return old;
			}
		}
	} //namespace detail
	#define rexy_cx_swap(...) detail::cx_swap(__VA_ARGS__)
	#define rexy_cx_exchange(...) detail::cx_exchange(__VA_ARGS__)
#endif

#endif