tdesktop/Telegram/SourceFiles/base/value_ordering.h

145 lines
4.0 KiB
C++

/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.
For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#pragma once
#include <utility>
namespace base {
namespace details {
template <
typename Type,
typename Operator,
typename = decltype(Operator{}(
std::declval<Type>(),
std::declval<Type>()))>
char test_operator(const Type &, const Operator &);
int test_operator(...);
template <typename Type, template <typename> typename Operator>
struct has_operator
: std::bool_constant<
sizeof(test_operator(
std::declval<Type>(),
std::declval<Operator<Type>>()
)) == sizeof(char)> {
};
template <
typename Type,
template <typename> typename Operator>
constexpr bool has_operator_v
= has_operator<Type, Operator>::value;
template <typename Type>
constexpr bool has_less_v = has_operator_v<Type, std::less>;
template <typename Type>
constexpr bool has_greater_v = has_operator_v<Type, std::greater>;
template <typename Type>
constexpr bool has_less_equal_v = has_operator_v<Type, std::less_equal>;
template <typename Type>
constexpr bool has_greater_equal_v = has_operator_v<Type, std::greater_equal>;
template <typename Type>
constexpr bool has_equal_to_v = has_operator_v<Type, std::equal_to>;
template <typename Type>
constexpr bool has_not_equal_to_v = has_operator_v<Type, std::not_equal_to>;
} // namespace details
} // namespace base
template <
typename ValueType,
typename Helper = decltype(
value_ordering_helper(std::declval<ValueType>()))>
inline auto operator<(const ValueType &a, const ValueType &b)
-> std::enable_if_t<base::details::has_less_v<Helper>, bool> {
return value_ordering_helper(a) < value_ordering_helper(b);
}
template <
typename ValueType,
typename Helper = decltype(
value_ordering_helper(std::declval<ValueType>()))>
inline auto operator>(const ValueType &a, const ValueType &b)
-> std::enable_if_t<
base::details::has_greater_v<Helper>
|| base::details::has_less_v<Helper>,
bool
> {
if constexpr (base::details::has_greater_v<Helper>) {
return value_ordering_helper(a) > value_ordering_helper(b);
} else {
return value_ordering_helper(b) < value_ordering_helper(a);
}
}
template <
typename ValueType,
typename Helper = decltype(
value_ordering_helper(std::declval<ValueType>()))>
inline auto operator<=(const ValueType &a, const ValueType &b)
-> std::enable_if_t<
base::details::has_less_equal_v<Helper>
|| base::details::has_less_v<Helper>,
bool
> {
if constexpr (base::details::has_less_equal_v<Helper>) {
return value_ordering_helper(a) <= value_ordering_helper(b);
} else {
return !(value_ordering_helper(b) < value_ordering_helper(a));
}
}
template <
typename ValueType,
typename Helper = decltype(
value_ordering_helper(std::declval<ValueType>()))>
inline auto operator>=(const ValueType &a, const ValueType &b)
-> std::enable_if_t<
base::details::has_greater_equal_v<Helper>
|| base::details::has_less_v<Helper>,
bool
> {
if constexpr (base::details::has_greater_equal_v<Helper>) {
return value_ordering_helper(a) >= value_ordering_helper(b);
} else {
return !(value_ordering_helper(a) < value_ordering_helper(b));
}
}
template <
typename ValueType,
typename Helper = decltype(
value_ordering_helper(std::declval<ValueType>()))>
inline auto operator==(const ValueType &a, const ValueType &b)
-> std::enable_if_t<base::details::has_equal_to_v<Helper>, bool> {
return value_ordering_helper(a) == value_ordering_helper(b);
}
template <
typename ValueType,
typename Helper = decltype(
value_ordering_helper(std::declval<ValueType>()))>
inline auto operator!=(const ValueType &a, const ValueType &b)
-> std::enable_if_t<
base::details::has_not_equal_to_v<Helper>
|| base::details::has_equal_to_v<Helper>,
bool
> {
if constexpr (base::details::has_not_equal_to_v<Helper>) {
return value_ordering_helper(a) != value_ordering_helper(b);
} else {
return !(value_ordering_helper(a) == value_ordering_helper(b));
}
}