mirror of https://github.com/procxx/kepka.git
75 lines
1.5 KiB
C++
75 lines
1.5 KiB
C++
#ifndef MAPBOX_UTIL_OPTIONAL_HPP
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#define MAPBOX_UTIL_OPTIONAL_HPP
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#pragma message("This implementation of optional is deprecated. See https://github.com/mapbox/variant/issues/64.")
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#include <type_traits>
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#include <utility>
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#include <mapbox/variant.hpp>
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namespace mapbox {
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namespace util {
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template <typename T>
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class optional
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{
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static_assert(!std::is_reference<T>::value, "optional doesn't support references");
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struct none_type
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{
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};
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variant<none_type, T> variant_;
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public:
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optional() = default;
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optional(optional const& rhs)
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{
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if (this != &rhs)
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{ // protect against invalid self-assignment
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variant_ = rhs.variant_;
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}
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}
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optional(T const& v) { variant_ = v; }
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explicit operator bool() const noexcept { return variant_.template is<T>(); }
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T const& get() const { return variant_.template get<T>(); }
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T& get() { return variant_.template get<T>(); }
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T const& operator*() const { return this->get(); }
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T operator*() { return this->get(); }
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optional& operator=(T const& v)
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{
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variant_ = v;
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return *this;
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}
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optional& operator=(optional const& rhs)
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{
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if (this != &rhs)
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{
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variant_ = rhs.variant_;
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}
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return *this;
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}
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template <typename... Args>
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void emplace(Args&&... args)
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{
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variant_ = T{std::forward<Args>(args)...};
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}
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void reset() { variant_ = none_type{}; }
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}; // class optional
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} // namespace util
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} // namespace mapbox
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#endif // MAPBOX_UTIL_OPTIONAL_HPP
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