toast::Box< T > Class Template Reference

Intrusive reference-counted handle to a Node. More...

#include <box.hpp>

Inheritance diagram for toast::Box< T >:

Public Member Functions
	Box () noexcept=default
	Default-constructs an empty (null) box; does not allocate anything.
	Box (std::nullptr_t) noexcept
	Constructs an empty (null) box; equivalent to the default constructor.
	Box (_detail::ControlBox *control_box) noexcept
	Low-level constructor used internally by the node allocation path; prefer constructing from a Node& or Node*.
	Box (const T *node) noexcept
	Constructs from a live node pointer; safe to call with null (produces an empty box); increments ref count.
	Box (const T &node) noexcept
	Constructs from a live node reference; increments ref count.
	Box (const Box &other) noexcept
	Shares ownership with other; increments ref count.
auto	operator= (const Box &other) noexcept -> Box &
	Shares ownership with other; increments ref count.
	Box (Box &&other) noexcept
	Transfers ownership from other; source becomes empty without touching the ref count.
auto	operator= (Box &&other) noexcept -> Box &
	Transfers ownership from other; source becomes empty without touching the ref count.
template<typename U> requires std::convertible_to<U*, T*>
	Box (const Box< U > &other) noexcept
	Derived-type copy; only enabled when U* is implicitly convertible to T*; increments ref count.
template<typename U> requires std::convertible_to<U*, T*>
auto	operator= (const Box< U > &other) noexcept -> Box &
	Derived-type copy assignment; only enabled when U* is implicitly convertible to T*.
template<typename U> requires std::convertible_to<U*, T*>
	Box (Box< U > &&other) noexcept
	Derived-type move; transfers ownership without touching the ref count.
template<typename U> requires std::convertible_to<U*, T*>
auto	operator= (Box< U > &&other) noexcept -> Box &
	Derived-type move assignment.
auto	exists () const noexcept -> bool
	Whether this box holds a live node.
auto	operator<=> (const Box &other) const noexcept -> std::strong_ordering
auto	operator== (const Box &other) const noexcept -> bool
	operator bool () const noexcept
	operator T& () noexcept
auto	operator-> () noexcept -> T *
auto	operator* () noexcept -> T &
	operator const T & () const noexcept
auto	operator-> () const noexcept -> const T *
auto	operator* () const noexcept -> const T &
template<typename U> requires std::derived_from<U, T>
auto	as () const noexcept -> Box< U >
	Downcasts to a derived type; a null Box returns a null Box rather than throwing.
auto	rid () const noexcept -> size_t
	Raw identity of the underlying ControlBox as a pointer value; stable for the node's lifetime; used as a hash key.

Friends
struct	_detail::ControlBox

Detailed Description

template<typename T>
class toast::Box< T >

Intrusive reference-counted handle to a Node.

The ControlBox lives inside the Node allocation itself, so all Box<Node> handles that refer to the same node share one reference count without any extra heap allocation. This design also makes the ref-count safe across DLL boundaries, where std::shared_ptr's control block would differ between modules.

A Box is null (empty) when default-constructed or after the node has been freed. Always call exists() before dereferencing.

Template Parameters

T	A Node subtype

See also

ControlBox, Node

Member Function Documentation

exists()

template<typename T>

auto toast::Box< T >::exists ( ) const -> bool

nodiscardnoexcept

Whether this box holds a live node.

Returns

false if the box is empty or if the node has been freed by World::drainDestroyQueue(); always check exists() before dereferencing

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The documentation for this class was generated from the following files:

• engine/src/toast/world/box.hpp
• engine/src/toast/world/box.inl