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Copy pathvariant.hpp
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628 lines (628 loc) · 27.7 KB
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#pragma once
#include<type_traits>
#include<algorithm>
#include<ranges>
#include<vector>
#include<string>
#include<cmath>
#ifndef __INTELLISENSE__
#include<meta>
#endif
#include<new>
#include"concepts.hpp"
#include"launder.hpp"
#include"assert.hpp"
#include"trap.hpp"
#include"eto.hpp"
#include"rtl.hpp"
#ifdef __INTELLISENSE__
namespace cppp{
struct uninitialize_t{} constexpr inline uninitialize;
template<enumeration auto v>
struct in_place_etor_t{};
template<enumeration auto v>
constexpr inline in_place_etor_t<v> in_place_etor;
template<enumeration E>
class variant{
public:
template<E v>
using lookup = __error_type;
variant() noexcept;
variant(uninitialize_t) noexcept;
template<E val,typename ...A>
variant(in_place_etor_t<val>,A&& ...a);
variant(const variant& other);
variant(variant&& other);
variant& operator=(const variant& other);
variant& operator=(variant&& other);
explicit operator bool();
E tag() const noexcept;
template<E val,typename ...A>
__error_type initialize(A&& ...a);
template<E val,typename ...A>
__error_type emplace(A&& ...a);
template<E val>
const __error_type& get() const noexcept;
template<E val>
__error_type& get() noexcept;
template<typename Fn>
__error_type visit(Fn&& fn);
template<typename Fn>
__error_type visit(Fn&& fn) const;
~variant();
};
template<enumeration E>
class heap_variant{
public:
template<E v>
using lookup = __error_type;
constexpr heap_variant() noexcept;
constexpr heap_variant(uninitialize_t) noexcept;
template<E val,typename ...A>
constexpr heap_variant(in_place_etor_t<val>,A&& ...a);
constexpr heap_variant(const heap_variant& other);
constexpr heap_variant(heap_variant&& other);
constexpr heap_variant& operator=(const heap_variant& other);
constexpr heap_variant& operator=(heap_variant&& other);
constexpr explicit operator bool();
constexpr E tag() const noexcept;
template<E val,typename ...A>
constexpr __error_type initialize(A&& ...a);
template<E val,typename ...A>
constexpr __error_type emplace(A&& ...a);
template<E val>
constexpr const __error_type& get() const noexcept;
template<E val>
constexpr __error_type& get() noexcept;
template<typename Fn>
constexpr __error_type visit(Fn&& fn);
template<typename Fn>
constexpr __error_type visit(Fn&& fn) const;
constexpr ~heap_variant();
};
}
#else
namespace cppp{
namespace detail{
struct etor_annot{
std::meta::info type;
};
consteval std::meta::info etor_type(std::meta::info etor){
using namespace std::literals;
if(std::vector<std::meta::info> etor_annots{annotations_of_with_type(etor,^^etor_annot)};!etor_annots.empty()){
if(etor_annots.size() > 1uz) throw std::meta::exception(u8"cppp::variant: enumerator has more than one annotation"sv,etor);
return extract<etor_annot>(etor_annots.front()).type;
}else{
std::vector<std::meta::info> annots{annotations_of(etor)};
if(annots.empty()) return ^^void;
if(annots.size() == 1uz && type_of(annots.front()) == dealias(^^std::meta::info) && is_type(extract<std::meta::info>(annots.front()))){
// GCC, you should know better than to complain that NRVO is not done on a std::meta::info instance...
// I know we can just copy it manually, but let's do the Right Thing and follow https://marralesfios.github.io/blog/nrvo
return [&annots,etor]consteval{
std::meta::info type = extract<std::meta::info>(annots.front());
if(is_lvalue_reference_type(type) || is_rvalue_reference_type(type)){
throw std::meta::exception(u8"cppp::variant: enumerator type must not be a reference type"sv,etor);
}
if(is_function_type(type)){
throw std::meta::exception(u8"cppp::variant: enumerator type must not be a function"sv,etor);
}
return type;
}();
}else throw std::meta::exception(u8"cppp::variant: enumerator does not have an unambiguous type annotation"sv,etor);
}
}
template<std::size_t n>
struct store_value{
constexpr static std::size_t value = n;
};
template<bool b>
struct store_flag{
constexpr static bool value = b;
};
template<typename E>
struct etor_info{
E v;
std::meta::info t;
};
template<typename E,etor_info<E> ...etor_infos>
class enum_info_base{
public:
constexpr static std::array<etor_info<E>,sizeof...(etor_infos)> infos{etor_infos...};
private:
template<E v>
struct _lookup;
consteval{
using namespace std::literals;
for(std::size_t i=0uz;i<infos.size();++i){
define_aggregate(substitute(^^_lookup,{std::meta::reflect_constant(infos[i].v)}),{data_member_spec(substitute(^^store_value,{std::meta::reflect_constant(i)}),{.name=u8"_tag"sv})});
}
}
template<E v>
constexpr static std::size_t member_lookup = decltype(_lookup<v>::_tag)::value;
public:
template<E v>
using lookup = [:infos[member_lookup<v>].t:];
template<E v>
constexpr static std::meta::info lookup_member = infos[member_lookup<v>].mem;
consteval static bool is_nothrow_copy_constructible() noexcept{
for(const detail::etor_info<E>& ei : infos){
if(!is_nothrow_copy_constructible_type(ei.t)) return false;
}
return true;
}
consteval static bool is_nothrow_move_constructible() noexcept{
for(const detail::etor_info<E>& ei : infos){
if(!is_nothrow_move_constructible_type(ei.t)) return false;
}
return true;
}
constexpr static bool is_optional = is_void_type(infos[0uz].t);
consteval static bool is_nothrow_copy_assignable() noexcept{
if(!is_optional) return true;
if(!is_nothrow_copy_constructible()) return false;
for(const detail::etor_info<E>& ei : infos){
if(!is_nothrow_copy_assignable_type(ei.t)) return false;
}
return true;
}
consteval static bool is_nothrow_move_assignable() noexcept{
if(!is_optional) return true;
if(!is_nothrow_move_constructible()) return false;
for(const detail::etor_info<E>& ei : infos){
if(!is_nothrow_move_assignable_type(ei.t)) return false;
}
return true;
}
};
template<typename E,std::size_t s,std::size_t a,etor_info<E> ...etor_infos>
class inplace_enum_info_base : public enum_info_base<E,etor_infos...>{
public:
constexpr static std::size_t size = s;
constexpr static std::size_t alignment = a;
};
template<enumeration E>
using enum_info = [:[]consteval static{
std::vector<std::meta::info> etor_infos{^^E};
for(std::meta::info etor : enumerators_of(^^E)){
std::meta::info t = etor_type(etor);
etor_infos.emplace_back(std::meta::reflect_constant(etor_info<E>{.v=extract<E>(etor),.t=t}));
}
return substitute(^^enum_info_base,etor_infos);
}():];
template<enumeration E>
using inplace_enum_info = [:[]consteval static{
std::vector<std::meta::info> etor_infos;
std::size_t size = 0uz;
std::size_t alignment = 1uz;
for(std::meta::info etor : enumerators_of(^^E)){
std::meta::info t = etor_type(etor);
etor_infos.emplace_back(std::meta::reflect_constant(etor_info<E>{.v=extract<E>(etor),.t=t}));
if(!is_void_type(t)){
size = std::max(size,size_of(t));
alignment = std::max(alignment,alignment_of(t));
}
}
return substitute(^^inplace_enum_info_base,std::views::concat(rtl<std::initializer_list<std::meta::info>>({^^E,std::meta::reflect_constant(size),std::meta::reflect_constant(alignment)}),etor_infos));
}():];
struct inplace_destroy{
constexpr static void operator()() noexcept{}
template<typename T>
constexpr static void operator()(T& v) noexcept(std::is_nothrow_destructible_v<T>){
v.~T();
}
};
}
template<typename T>
constexpr inline detail::etor_annot etor{.type = ^^T};
struct uninitialize_t{} constexpr inline uninitialize;
template<enumeration auto v>
struct in_place_etor_t{};
template<enumeration auto v>
constexpr inline in_place_etor_t<v> in_place_etor;
template<enumeration E>
class variant{
#if __cpp_consteval >= 202406L
#warning P4101 might be merged! Check to see if access_constexpr_etor is still necessary.
#endif
// At least before P4101, etor_info<E> being a consteval-only type makes accessing infos[...].v promote the entire containing function to consteval. This is unacceptable.
template<E v>
constexpr static E access_constexpr_etor = v;
using info_t = detail::inplace_enum_info<E>;
[[no_unique_address]] potentially_empty_array<std::byte,info_t::size,info_t::alignment> data;
E _tag;
template<typename T>
T& _get() noexcept{
return read_object<T>(data.data());
}
template<typename T>
const T& _get() const noexcept{
return read_object<T>(data.data());
}
void _destroy() noexcept{
visit(detail::inplace_destroy());
}
template<typename T,typename ...A>
T& emplace_construct(A&& ...a) noexcept(std::is_nothrow_constructible_v<T,A...>){
return *new(data.data()) T(std::forward<A>(a)...);
}
template<typename T,typename ...A>
T& _emplace(A&& ...a) noexcept(!info_t::is_optional || std::is_nothrow_constructible_v<T,A...>){
_destroy();
if constexpr(info_t::is_optional && !std::is_nothrow_constructible_v<T,A...>){
try{
return emplace_construct<T>(std::forward<A>(a)...);
}catch(...){
_tag = access_constexpr_etor<info_t::infos[0uz].v>;
throw;
}
}else{
return emplace_construct<T>(std::forward<A>(a)...);
}
}
public:
template<E v>
using lookup = info_t::template lookup<v>;
variant() noexcept requires(info_t::is_optional) : _tag(access_constexpr_etor<info_t::infos[0uz].v>){}
variant(uninitialize_t) noexcept{}
template<E val,typename ...A> requires(!std::is_void_v<lookup<val>>)
variant(in_place_etor_t<val>,A&& ...a) noexcept(noexcept(new(data.data()) lookup<val>(std::forward<A>(a)...))) : _tag(val){
emplace_construct<lookup<val>>(std::forward<A>(a)...);
}
template<E val> requires(std::is_void_v<lookup<val>>)
variant(in_place_etor_t<val>) noexcept : _tag(val){}
variant(const variant& other) noexcept(info_t::is_nothrow_copy_constructible()) : _tag(other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
emplace_construct<typename[:ei.t:]>(other._get<typename[:ei.t:]>());
}
}
}
}
variant(variant&& other) noexcept(info_t::is_nothrow_move_constructible()) : _tag(other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
emplace_construct<typename[:ei.t:]>(std::move(other._get<typename[:ei.t:]>()));
}
}
}
}
variant& operator=(const variant& other) noexcept(info_t::is_nothrow_copy_assignable()){
if(_tag == other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
_get<typename[:ei.t:]>() = other._get<typename[:ei.t:]>();
}
}
}
}else{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == other._tag){
_emplace<typename[:ei.t:]>(other._get<typename[:ei.t:]>());
}
}
}
_tag = other._tag;
}
return *this;
}
variant& operator=(variant&& other) noexcept(info_t::is_nothrow_move_assignable()){
if(_tag == other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
_get<typename[:ei.t:]>() = std::move(other._get<typename[:ei.t:]>());
}
}
}
}else{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == other._tag){
_emplace<typename[:ei.t:]>(std::move(other._get<typename[:ei.t:]>()));
}
}
}
_tag = other._tag;
}
return *this;
}
explicit operator bool() requires(info_t::is_optional){
return _tag != access_constexpr_etor<info_t::infos[0uz].v>;
}
E tag() const noexcept{
return _tag;
}
template<E val,typename ...A>
lookup<val>& initialize(A&& ...a) noexcept(std::is_nothrow_constructible_v<lookup<val>,A...>){
lookup<val>& ref = emplace_construct<lookup<val>>(std::forward<A>(a)...);
_tag = val;
return ref;
}
template<E val>
void initialize() noexcept requires(std::is_void_v<lookup<val>>){
_tag = val;
}
template<E val,typename ...A>
lookup<val>& emplace(A&& ...a) noexcept(!info_t::is_optional || std::is_nothrow_constructible_v<lookup<val>,A...>){
lookup<val>& ref = _emplace<lookup<val>>(std::forward<A>(a)...);
_tag = val;
return ref;
}
template<E val>
void emplace() noexcept requires(std::is_void_v<lookup<val>>){
_destroy();
_tag = val;
}
template<E val>
const lookup<val>& get() const noexcept{
CPPP_ASSERT(_tag == val);
return _get<lookup<val>>();
}
template<E val>
lookup<val>& get() noexcept{
CPPP_ASSERT(_tag == val);
return _get<lookup<val>>();
}
template<typename Fn>
decltype(auto) visit(Fn&& fn){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if(ei.v == _tag){
if constexpr(is_void_type(ei.t)){
return std::forward<Fn>(fn)();
}else{
return std::forward<Fn>(fn)(_get<typename[:ei.t:]>());
}
}
}
unreachable();
}
template<typename Fn>
decltype(auto) visit(Fn&& fn) const{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if(ei.v == _tag){
if constexpr(is_void_type(ei.t)){
return std::forward<Fn>(fn)();
}else{
return std::forward<Fn>(fn)(_get<typename[:ei.t:]>());
}
}
}
unreachable();
}
~variant(){
_destroy();
}
};
namespace detail{
template<typename T>
concept eligible_for_soo = sizeof(T) <= sizeof(void*) && alignof(T) <= alignof(void*);
}
template<enumeration E>
class heap_variant{
#if __cpp_consteval >= 202406L
#warning P4101 might be merged! Check to see if access_constexpr_etor is still necessary.
#endif
// At least before P4101, etor_info<E> being a consteval-only type makes accessing infos[...].v promote the entire containing function to consteval. This is unacceptable.
template<E v>
constexpr static E access_constexpr_etor = v;
using info_t = detail::enum_info<E>;
alignas(void*) std::byte data[sizeof(void*)];
E _tag;
template<typename T>
constexpr T& _get() noexcept{
if constexpr(detail::eligible_for_soo<T>){
return read_object<T>(data);
}else{
return *static_cast<T*>(read_object<void*>(data));
}
}
template<typename T>
constexpr const T& _get() const noexcept{
if constexpr(detail::eligible_for_soo<T>){
return read_object<T>(data);
}else{
return *static_cast<const T*>(read_object<void*>(data));
}
}
constexpr void _destroy() noexcept{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if(ei.v == _tag){
if constexpr(!is_void_type(ei.t)){
typename[:ei.t:]* ptr = &_get<typename[:ei.t:]>();
if constexpr(detail::eligible_for_soo<typename[:ei.t:]>){
std::destroy_at(ptr);
}else{
delete ptr;
std::destroy_at(&read_object<void*>(data));
}
}
}
}
}
template<typename T,typename ...A>
constexpr T& emplace_construct(A&& ...a) noexcept(std::is_nothrow_constructible_v<T,A...>){
if constexpr(detail::eligible_for_soo<T>){
return *new(data) T(std::forward<A>(a)...);
}else{
using voidp = void*;
T* p;
new(data) voidp(p = new T(std::forward<A>(a)...));
return *p;
}
}
template<typename T,typename ...A>
constexpr T& _emplace(A&& ...a) noexcept(std::is_nothrow_constructible_v<T,A...> || (detail::eligible_for_soo<T> && !info_t::is_optional)){
if constexpr(detail::eligible_for_soo<T>){
_destroy();
if constexpr(info_t::is_optional && !std::is_nothrow_constructible_v<T,A...>){
try{
return *new(data) T(std::forward<A>(a)...);
}catch(...){
_tag = access_constexpr_etor<info_t::infos[0uz].v>;
throw;
}
}else{
return *new(data) T(std::forward<A>(a)...);
}
}else{
T* alloc = new T(std::forward<A>(a)...);
_destroy();
using voidp = void*;
new(data) voidp(alloc);
return *alloc;
}
}
public:
template<E v>
using lookup = info_t::template lookup<v>;
constexpr heap_variant() noexcept requires(info_t::is_optional) : data{}, _tag(access_constexpr_etor<info_t::infos[0uz].v>){}
constexpr heap_variant(uninitialize_t) noexcept{}
template<E val,typename ...A> requires(!std::is_void_v<lookup<val>>)
constexpr heap_variant(in_place_etor_t<val>,A&& ...a) : data{}, _tag(val){
emplace_construct<lookup<val>>(std::forward<A>(a)...);
}
template<E val> requires(std::is_void_v<lookup<val>>)
constexpr heap_variant(in_place_etor_t<val>) noexcept : data{}, _tag(val){}
constexpr heap_variant(const heap_variant& other) noexcept(info_t::is_nothrow_copy_constructible()) : data{}, _tag(other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
emplace_construct<typename[:ei.t:]>(other._get<typename[:ei.t:]>());
}
}
}
}
constexpr heap_variant(heap_variant&& other) noexcept(info_t::is_nothrow_move_constructible()) : data{}, _tag(other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
emplace_construct<typename[:ei.t:]>(std::move(other._get<typename[:ei.t:]>()));
}
}
}
}
// TODO: revise noexcept specification
constexpr heap_variant& operator=(const heap_variant& other){
if(_tag == other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == _tag){
_get<typename[:ei.t:]>() = other._get<typename[:ei.t:]>();
}
}
}
}else{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == other._tag){
_emplace<typename[:ei.t:]>(other._get<typename[:ei.t:]>());
}
}
}
_tag = other._tag;
}
return *this;
}
// TODO: revise noexcept specification
constexpr heap_variant& operator=(heap_variant&& other){
if(_tag == other._tag){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if(ei.v == _tag){
if constexpr(!is_void_type(ei.t)){
_get<typename[:ei.t:]>() = std::move(other._get<typename[:ei.t:]>());
}
}
}
}else{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if constexpr(!is_void_type(ei.t)){
if(ei.v == other._tag){
_emplace<typename[:ei.t:]>(std::move(other._get<typename[:ei.t:]>()));
}
}
}
_tag = other._tag;
}
return *this;
}
constexpr explicit operator bool() requires(info_t::is_optional){
return _tag != access_constexpr_etor<info_t::infos[0uz].v>;
}
constexpr E tag() const noexcept{
return _tag;
}
template<E val,typename ...A>
constexpr lookup<val>& initialize(A&& ...a) noexcept(std::is_nothrow_constructible_v<lookup<val>,A...>){
lookup<val>& ref = emplace_construct<lookup<val>>(std::forward<A>(a)...);
_tag = val;
return ref;
}
template<E val>
constexpr void initialize() noexcept requires(std::is_void_v<lookup<val>>){
_tag = val;
}
template<E val,typename ...A>
constexpr lookup<val>& emplace(A&& ...a) noexcept(std::is_nothrow_constructible_v<lookup<val>,A...> || (detail::eligible_for_soo<lookup<val>> && !info_t::is_optional)){
lookup<val>& ref = _emplace<lookup<val>>(std::forward<A>(a)...);
_tag = val;
return ref;
}
template<E val>
constexpr void emplace() noexcept requires(std::is_void_v<lookup<val>>){
_destroy();
_tag = val;
}
template<E val>
constexpr const lookup<val>& get() const noexcept{
if consteval{
cppp::consteval_assert(_tag == val);
}else{
CPPP_ASSERT(_tag == val);
}
return _get<lookup<val>>();
}
template<E val>
constexpr lookup<val>& get() noexcept{
if consteval{
cppp::consteval_assert(_tag == val);
}else{
CPPP_ASSERT(_tag == val);
}
return _get<lookup<val>>();
}
template<typename Fn>
constexpr decltype(auto) visit(Fn&& fn){
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if(ei.v == _tag){
if constexpr(is_void_type(ei.t)){
return std::forward<Fn>(fn)();
}else{
return std::forward<Fn>(fn)(_get<typename[:ei.t:]>());
}
}
}
unreachable();
}
template<typename Fn>
constexpr decltype(auto) visit(Fn&& fn) const{
template for(constexpr const detail::etor_info<E>& ei : info_t::infos){
if(ei.v == _tag){
if constexpr(is_void_type(ei.t)){
return std::forward<Fn>(fn)();
}else{
return std::forward<Fn>(fn)(_get<typename[:ei.t:]>());
}
}
}
unreachable();
}
constexpr ~heap_variant(){
_destroy();
}
};
}
#endif
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