forked from Bananymous/banan-os
BAN: Variant now has variadic template types
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Bananymous
parent
5494e2c125
commit
04ac23b67c
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@ -72,7 +72,7 @@ namespace BAN
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: m_data(move(error))
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{}
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bool is_error() const { return m_data.template is<Error>(); }
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bool is_error() const { return m_data.template has<Error>(); }
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const Error& error() const { return m_data.template get<Error>(); }
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Error& error() { return m_data.template get<Error>(); }
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const T& value() const { return m_data.template get<T>(); }
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@ -7,141 +7,226 @@
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namespace BAN
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{
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template<typename T1, typename T2>
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class Variant
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namespace detail
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{
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public:
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static_assert(!is_same_v<T1, T2>);
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Variant() = default;
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template<typename T>
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constexpr size_t max_size() { return sizeof(T); }
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template<typename T0, typename T1, typename... Ts>
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constexpr size_t max_size() { return sizeof(T0) > sizeof(T1) ? max_size<T0, Ts...>() : max_size<T1, Ts...>(); }
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Variant(const T1& value) { set(value); }
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Variant(T1&& value) { set(move(value)); }
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Variant(const T2& value) { set(value); }
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Variant(T2&& value) { set(move(value)); }
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template<typename T>
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constexpr size_t max_align() { return alignof(T); }
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template<typename T0, typename T1, typename... Ts>
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constexpr size_t max_align() { return alignof(T0) > alignof(T1) ? max_align<T0, Ts...>() : max_align<T1, Ts...>(); }
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Variant(const Variant<T1, T2>& other) { *this = other; }
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Variant(Variant<T1, T2>&& other) { *this = move(other); }
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~Variant() { clear(); }
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Variant<T1, T2>& operator=(const Variant<T1, T2>& other);
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Variant<T1, T2>& operator=(Variant<T1, T2>&& other);
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template<typename U>
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bool is() const;
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template<typename U>
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void set(U&&);
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template<typename U>
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void set(const U& value) { set(move(U(value))); }
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template<typename U>
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const U& get() const;
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template<typename U>
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U& get();
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void clear();
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private:
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static constexpr uint32_t m_size = Math::max(sizeof(T1), sizeof(T2));
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alignas(Math::max(alignof(T1), alignof(T2))) uint8_t m_storage[m_size] = {};
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uint32_t m_index = 0;
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};
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template<typename T1, typename T2>
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Variant<T1, T2>& Variant<T1, T2>::operator=(const Variant<T1, T2>& other)
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template<typename T, typename T0, typename... Ts>
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constexpr size_t index()
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{
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clear();
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if (other.is<T1>())
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set(other.get<T1>());
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if (other.is<T2>())
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set(other.get<T2>());
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return *this;
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if constexpr(is_same_v<T, T0>)
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return 0;
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else if constexpr(sizeof...(Ts) == 0)
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return 1;
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else
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return index<T, Ts...>() + 1;
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}
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template<typename T1, typename T2>
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Variant<T1, T2>& Variant<T1, T2>::operator=(Variant<T1, T2>&& other)
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template<typename T, typename... Ts>
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void destruct(size_t index, uint8_t* data)
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{
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if (index == 0)
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reinterpret_cast<T*>(data)->~T();
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else if constexpr(sizeof...(Ts) > 0)
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destruct<Ts...>(index - 1, data);
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else
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ASSERT_NOT_REACHED();
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}
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template<typename T, typename... Ts>
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void move_construct(size_t index, uint8_t* source, uint8_t* target)
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{
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if (index == 0)
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new (target) T(move(*reinterpret_cast<T*>(source)));
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else if constexpr(sizeof...(Ts) > 0)
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move_construct<Ts...>(index - 1, source, target);
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else
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ASSERT_NOT_REACHED();
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}
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template<typename T, typename... Ts>
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void copy_construct(size_t index, const uint8_t* source, uint8_t* target)
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{
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if (index == 0)
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new (target) T(*reinterpret_cast<const T*>(source));
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else if constexpr(sizeof...(Ts) > 0)
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copy_construct<Ts...>(index - 1, source, target);
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else
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ASSERT_NOT_REACHED();
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}
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template<typename T, typename... Ts>
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void move_assign(size_t index, uint8_t* source, uint8_t* target)
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{
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if (index == 0)
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*reinterpret_cast<T*>(target) = move(*reinterpret_cast<T*>(source));
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else if constexpr(sizeof...(Ts) > 0)
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move_assign<Ts...>(index - 1, source, target);
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else
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ASSERT_NOT_REACHED();
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}
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template<typename T, typename... Ts>
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void copy_assign(size_t index, const uint8_t* source, uint8_t* target)
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{
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if (index == 0)
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*reinterpret_cast<T*>(target) = *reinterpret_cast<const T*>(source);
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else if constexpr(sizeof...(Ts) > 0)
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copy_assign<Ts...>(index - 1, source, target);
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else
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ASSERT_NOT_REACHED();
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}
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}
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template<typename... Ts>
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requires (!is_lvalue_reference_v<Ts> && ...)
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class Variant
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{
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private:
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template<typename T>
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static constexpr bool can_have() { return detail::index<T, Ts...>() != invalid_index(); }
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static constexpr size_t invalid_index() { return sizeof...(Ts); }
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public:
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Variant()
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: m_index(invalid_index())
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{ }
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Variant(Variant&& other)
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: m_index(other.m_index)
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{
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detail::move_construct<Ts...>(other.m_index, other.m_storage, m_storage);
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other.clear();
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}
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Variant(const Variant& other)
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: m_index(other.m_index)
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{
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detail::copy_construct<Ts...>(other.m_index, other.m_storage, m_storage);
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}
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template<typename T>
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Variant(T&& value) requires (can_have<T>())
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: m_index(detail::index<T, Ts...>())
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{
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new (m_storage) T(move(value));
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}
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template<typename T>
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Variant(const T& value) requires (can_have<T>())
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: m_index(detail::index<T, Ts...>())
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{
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new (m_storage) T(value);
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}
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~Variant()
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{
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clear();
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if (other.is<T1>())
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set(move(other.get<T1>()));
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if (other.is<T2>())
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set(move(other.get<T2>()));
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}
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Variant& operator=(Variant&& other)
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{
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if (m_index == other.m_index)
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{
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detail::move_assign<Ts...>(m_index, other.m_storage, m_storage);
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}
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else
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{
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clear();
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detail::move_construct<Ts...>(other.m_index, other.m_storage, m_storage);
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m_index = other.m_index;
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}
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other.clear();
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return *this;
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}
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template<typename T1, typename T2>
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template<typename U>
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bool Variant<T1, T2>::is() const
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Variant& operator=(const Variant& other)
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{
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if constexpr(is_same_v<T1, U>)
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return m_index == 1;
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if constexpr(is_same_v<T2, U>)
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return m_index == 2;
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return false;
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if (m_index == other.m_index)
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{
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detail::copy_assign<Ts...>(m_index, other.m_storage, m_storage);
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}
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template<typename T1, typename T2>
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template<typename U>
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void Variant<T1, T2>::set(U&& value)
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else
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{
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static_assert(is_same_v<T1, U> || is_same_v<T2, U>);
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clear();
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if constexpr(is_same_v<T1, U>)
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{
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new (m_storage) T1(move(value));
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m_index = 1;
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detail::copy_construct<Ts...>(other.m_index, other.m_storage, m_storage);
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m_index = other.m_index;
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}
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if constexpr(is_same_v<T2, U>)
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return *this;
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}
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template<typename T>
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Variant& operator=(T&& value) requires (can_have<T>())
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{
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new (m_storage) T2(move(value));
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m_index = 2;
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set(move(value));
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return *this;
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}
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template<typename T>
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Variant& operator=(const T& value) requires (can_have<T>())
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{
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set(value);
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return *this;
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}
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template<typename T>
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bool has() const requires (can_have<T>())
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{
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return m_index == detail::index<T, Ts...>();
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}
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template<typename T>
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void set(T&& value) requires (can_have<T>())
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{
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clear();
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m_index = detail::index<T, Ts...>();
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new (m_storage) T(move(value));
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}
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template<typename T>
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void set(const T& value) requires (can_have<T>())
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{
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clear();
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m_index = detail::index<T, Ts...>();
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new (m_storage) T(value);
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}
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template<typename T>
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T& get() requires (can_have<T>())
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{
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ASSERT(has<T>());
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return (T&)m_storage;
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}
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template<typename T>
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const T& get() const requires (can_have<T>())
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{
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ASSERT(has<T>());
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return (const T&)m_storage;
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}
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void clear()
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{
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if (m_index != invalid_index())
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{
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detail::destruct<Ts...>(m_index, m_storage);
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m_index = invalid_index();
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}
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}
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template<typename T1, typename T2>
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template<typename U>
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const U& Variant<T1, T2>::get() const
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{
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static_assert(is_same_v<T1, U> || is_same_v<T2, U>);
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if constexpr(is_same_v<T1, U>)
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{
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ASSERT(m_index == 1);
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return *(T1*)m_storage;
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}
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if constexpr(is_same_v<T2, U>)
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{
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ASSERT(m_index == 2);
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return *(T2*)m_storage;
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}
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}
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template<typename T1, typename T2>
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template<typename U>
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U& Variant<T1, T2>::get()
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{
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static_assert(is_same_v<T1, U> || is_same_v<T2, U>);
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if constexpr(is_same_v<T1, U>)
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{
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ASSERT(m_index == 1);
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return *(T1*)m_storage;
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}
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if constexpr(is_same_v<T2, U>)
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{
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ASSERT(m_index == 2);
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return *(T2*)m_storage;
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}
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}
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template<typename T1, typename T2>
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void Variant<T1, T2>::clear()
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{
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if (is<T1>()) ((T1*)m_storage)->~T1();
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if (is<T2>()) ((T2*)m_storage)->~T2();
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m_index = 0;
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}
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private:
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alignas(detail::max_align<Ts...>()) uint8_t m_storage[detail::max_size<Ts...>()] {};
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size_t m_index { invalid_index() };
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};
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}
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