James Ward | 22a4e15 | 2020-09-25 11:43:21 +0100 | [diff] [blame] | 1 | #ifndef MAPBOX_UTIL_OPTIONAL_HPP |
| 2 | #define MAPBOX_UTIL_OPTIONAL_HPP |
| 3 | |
| 4 | #pragma message("This implementation of optional is deprecated. See https://github.com/mapbox/variant/issues/64.") |
| 5 | |
| 6 | #include <type_traits> |
| 7 | #include <utility> |
| 8 | |
| 9 | #include <mapbox/variant.hpp> |
| 10 | |
| 11 | namespace mapbox { |
| 12 | namespace util { |
| 13 | |
| 14 | template <typename T> |
| 15 | class optional |
| 16 | { |
| 17 | static_assert(!std::is_reference<T>::value, "optional doesn't support references"); |
| 18 | |
| 19 | struct none_type |
| 20 | { |
| 21 | }; |
| 22 | |
| 23 | variant<none_type, T> variant_; |
| 24 | |
| 25 | public: |
| 26 | optional() = default; |
| 27 | |
| 28 | optional(optional const& rhs) |
| 29 | { |
| 30 | if (this != &rhs) |
| 31 | { // protect against invalid self-assignment |
| 32 | variant_ = rhs.variant_; |
| 33 | } |
| 34 | } |
| 35 | |
| 36 | optional(T const& v) { variant_ = v; } |
| 37 | |
| 38 | explicit operator bool() const noexcept { return variant_.template is<T>(); } |
| 39 | |
| 40 | T const& get() const { return variant_.template get<T>(); } |
| 41 | T& get() { return variant_.template get<T>(); } |
| 42 | |
| 43 | T const& operator*() const { return this->get(); } |
| 44 | T operator*() { return this->get(); } |
| 45 | |
| 46 | optional& operator=(T const& v) |
| 47 | { |
| 48 | variant_ = v; |
| 49 | return *this; |
| 50 | } |
| 51 | |
| 52 | optional& operator=(optional const& rhs) |
| 53 | { |
| 54 | if (this != &rhs) |
| 55 | { |
| 56 | variant_ = rhs.variant_; |
| 57 | } |
| 58 | return *this; |
| 59 | } |
| 60 | |
| 61 | template <typename... Args> |
| 62 | void emplace(Args&&... args) |
| 63 | { |
| 64 | variant_ = T{std::forward<Args>(args)...}; |
| 65 | } |
| 66 | |
| 67 | void reset() { variant_ = none_type{}; } |
| 68 | |
| 69 | }; // class optional |
| 70 | |
| 71 | } // namespace util |
| 72 | } // namespace mapbox |
| 73 | |
| 74 | #endif // MAPBOX_UTIL_OPTIONAL_HPP |