union.h File Reference

UnionCell<Ts...> closed-set polymorphic cell and its descriptor. More...

#include <parcel/cell.h>
#include <parcel/descriptor.h>
#include <array>
#include <cstddef>
#include <memory>
#include <stdexcept>
#include <string>
#include <string_view>
#include <tuple>
#include <type_traits>
#include <utility>
#include <variant>

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Classes
class	parcel::UnionCellTypeDescriptor< Ts >
	Descriptor for UnionCell<Ts...>. More...
class	parcel::UnionCell< Ts >
	Closed-set polymorphic cell — exactly one of Ts at runtime. More...
struct	parcel::Overload< Fs >
	Lambda-overload set helper for parcel::visit. More...

Functions
template<typename F , CellLike... Ts>
decltype(auto)	parcel::visit (F &&f, UnionCell< Ts... > &u)
	std::visit-style free function over UnionCell<Ts...>.
template<typename F , CellLike... Ts>
decltype(auto)	parcel::visit (F &&f, UnionCell< Ts... > const &u)
	Const overload of visit.
template<std::size_t I, CellLike... Ts>
auto &	parcel::get (UnionCell< Ts... > &u)
	Free get<I> over UnionCell<Ts...> mirroring std::get<I>(variant).
template<typename S , CellLike... Ts>
S &	parcel::get (UnionCell< Ts... > &u)
	Free get<S> selecting by storage type.
template<std::size_t I, CellLike... Ts>
auto *	parcel::get_if (UnionCell< Ts... > *u) noexcept
	Free get_if<I> over UnionCell<Ts...>; returns nullptr on miss.

Detailed Description

UnionCell<Ts...> closed-set polymorphic cell and its descriptor.

A UnionCell<Ts...> holds exactly one value drawn from a fixed set of cell alternatives. Storage is std::variant<typename Ts::storage_t...>. The wire kind id encodes every alternative kind in template order so each instantiation registers under its own kind. See the README "Unions" section.

Function Documentation

visit()

template<typename F , CellLike... Ts>

decltype(auto) parcel::visit	(	F &&	f,
		UnionCell< Ts... > &	u
	)

std::visit-style free function over UnionCell<Ts...>.

Calls f on the active alternative's storage. Mirrors std::visit(visitor, variant).