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100 lines
1.5 KiB
100 lines
1.5 KiB
#pragma once
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#include <type_traits>
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#include "gp_config.hpp"
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#include "gp/exception.hpp"
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#include "gp/memory.hpp"
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namespace gp{
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struct nullopt_t{};
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constexpr nullopt_t nullopt;
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template<typename T, bool B = std::is_final<T>::value || std::is_fundamental<T>::value>
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class optional;
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template<typename T>
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class optional<T,true>{
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bool ready = false;
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char buffer[sizeof(T)];
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public:
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constexpr optional()
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: ready{false}
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{}
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constexpr optional(nullopt_t)
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: ready{false}
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{}
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constexpr optional(T& value)
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: ready{true}
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{
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new(buffer) T(value);
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}
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constexpr optional(T&& value)
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: ready{true}
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{
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new(buffer) T(std::move(value));
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}
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constexpr bool has_value()
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{
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return ready;
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}
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constexpr T& value()
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{
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if constexpr (gp_config::has_exceptions)
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{
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if(!ready)
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{
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throw bad_optional{};
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}
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}
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return *reinterpret_cast<T*>(buffer);
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}
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};
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template<typename T>
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class optional<T,false>{
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bool ready = false;
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void* ptr;
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public:
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constexpr optional()
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: ready{false}
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{}
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constexpr optional(nullopt_t)
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: ready{false}
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{}
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constexpr optional(T& value)
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: ready{true}
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{
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ptr = (void*)new T(value);
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}
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constexpr optional(T&& value)
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: ready{true}
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{
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ptr = (void*)new T(std::move(value));
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}
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constexpr bool has_value()
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{
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return ready;
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}
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constexpr T& value()
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{
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if constexpr (gp_config::has_exceptions)
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{
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if(!ready)
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{
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throw bad_optional{};
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}
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}
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return *reinterpret_cast<T*>(ptr);
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}
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};
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}
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