/************************************************************************* * * Copyright 2016 Realm Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * **************************************************************************/ #pragma once #ifndef REALM_UTIL_OPTIONAL_HPP #define REALM_UTIL_OPTIONAL_HPP #include <optional> #include <ostream> namespace realm { namespace util { template <class T> using Optional = std::optional<T>; using None = std::nullopt_t; template <class T, class... Args> Optional<T> some(Args&&... args) { return std::make_optional<T>(std::forward<Args>(args)...); } using std::make_optional; constexpr auto none = std::nullopt; template <class T> struct RemoveOptional { using type = T; }; template <class T> struct RemoveOptional<Optional<T>> { using type = typename RemoveOptional<T>::type; // Remove recursively }; /** * Writes a T to an ostream, with special handling if T is a std::optional. * * This function supports both optional and non-optional Ts, so that callers don't need to do their own dispatch. */ template <class T> std::ostream& stream_possible_optional(std::ostream& os, const T& rhs) { return os << rhs; } template <class T> std::ostream& stream_possible_optional(std::ostream& os, const std::optional<T>& rhs) { if (rhs) { os << "some(" << *rhs << ")"; } else { os << "none"; } return os; } } // namespace util using util::none; } // namespace realm #endif // REALM_UTIL_OPTIONAL_HPP