co_ecs::const_entity_ref Class Reference

Represents a reference to an entity within a registry. More...

#include <entity_ref.hpp>

Public Member Functions
constexpr	const_entity_ref (const base_registry &registry, entity entity)
	Constructs a const entity reference for a specific entity in the given registry.
constexpr auto	archetype () const noexcept -> const archetype &
	Retrieves a constant reference to the archetype of the entity.
constexpr auto	alive () const noexcept -> bool
	Checks if the entity is currently active in the registry.
template<component... C>
constexpr auto	has () const noexcept -> bool
	Determines if the entity has all specified components.
template<component C>
constexpr auto	get () const -> const C &
	Retrieves a const-qualified component of type C from the entity in a read-only manner.
template<component C, component O, component... Args>
constexpr auto	get () const -> decltype(auto)
	Retrieves multiple components from the underlying registry for the current entity (const version).
constexpr auto	visit (auto &&func) const
	Visit all components of an entity and apply a function to them (const version).
auto	copy (base_registry &destination) const -> entity_ref
	Copies the current entity to another registry.
auto	copy (base_registry &destination, placeholder_entity placeholder) const
	Copies the current entity to another registry into a placeholder entity.
constexpr	operator entity () const noexcept
	Converts this const_entity_ref to its underlying entity.
constexpr	operator bool () const noexcept
	Checks if the underlying entity is valid.

Detailed Description

Represents a reference to an entity within a registry.

This class provides read only access to entity.

Constructor & Destructor Documentation

const_entity_ref()

constexpr co_ecs::const_entity_ref::const_entity_ref ( const base_registry & registry, entity entity )

inlineconstexpr

Constructs a const entity reference for a specific entity in the given registry.

Parameters

registry	Reference to the base_registry that manages the entity.
entity	The entity that this reference will encapsulate.

Member Function Documentation

alive()

constexpr auto co_ecs::const_entity_ref::alive ( ) const -> bool

inlineconstexprnoexcept

Checks if the entity is currently active in the registry.

This method queries the registry to determine if the entity is still active and has not been destroyed. It is particularly useful for validity checks before performing operations on the entity.

Returns

bool Returns true if the entity is active; otherwise, false.

archetype()

constexpr auto co_ecs::const_entity_ref::archetype ( ) const -> const archetype&

inlineconstexprnoexcept

Retrieves a constant reference to the archetype of the entity.

This method returns a reference to the archetype associated with the encapsulated entity. An archetype defines the configuration of components that an entity possesses in the entity-component system. Accessing the archetype can be useful for inspecting the structure and component makeup of the entity.

Returns

const archetype& A reference to the archetype of the entity.

copy() [1/2]

auto co_ecs::const_entity_ref::copy ( base_registry & destination ) const -> entity_ref

inline

Copies the current entity to another registry.

This method copies the current entity to a specified destination registry, creating a new entity in the destination registry.

Parameters

destination

The destination registry where the entity will be copied.

Returns

The copied entity reference in the destination registry.

copy() [2/2]

auto co_ecs::const_entity_ref::copy ( base_registry & destination, placeholder_entity placeholder ) const

inline

Copies the current entity to another registry into a placeholder entity.

This method copies the current entity to a specified destination registry, creating a new entity in the destination registry and associating it with a placeholder entity.

Parameters

destination	The destination registry where the entity will be copied.
placeholder	The placeholder entity in the destination registry.

Returns

The copied entity reference in the destination registry.

get() [1/2]

template<component C>

constexpr auto co_ecs::const_entity_ref::get ( ) const -> const C&

inlineconstexpr

Retrieves a const-qualified component of type C from the entity in a read-only manner.

This const method template is designed for read-only access to a specific component from the entity managed by the registry. It is used when the entity is expected to contain the component and modifications are not intended. If the requested component is not present, it throws a component_not_found exception.

Template Parameters

C	The type of the component to retrieve, specified as a const-qualified reference.

Returns

C A const reference to the requested component of the entity.

Exceptions

component_not_found

If the requested component C is not found in the entity.

get() [2/2]

template<component C, component O, component... Args>

constexpr auto co_ecs::const_entity_ref::get ( ) const -> decltype(auto)

inlineconstexpr

Retrieves multiple components from the underlying registry for the current entity (const version).

This method allows accessing multiple components associated with the current entity from the underlying registry in a const context.

Template Parameters

C	The first component type to retrieve.
O	The second component type to retrieve.
Args	Additional component types to retrieve.

Returns

A tuple containing the requested components.

has()

template<component... C>

constexpr auto co_ecs::const_entity_ref::has ( ) const -> bool

inlineconstexprnoexcept

Determines if the entity has all specified components.

This template method checks whether the entity has each of the components listed in the template arguments. This can be useful for conditional logic where actions depend on the presence of specific components in an entity. For example, an operation that should only be performed if an entity has both a position and velocity component.

Template Parameters

C	The component types to check for.

Returns

bool Returns true if the entity has all specified components; otherwise, false.

operator bool()

constexpr co_ecs::const_entity_ref::operator bool ( ) const

inlineconstexprnoexcept

Checks if the underlying entity is valid.

This conversion operator allows the entity_ref to be used in boolean contexts to check if the underlying entity is valid (i.e., has valid (id, generation) but may not be alive).

Returns

bool True if the underlying entity is valid, false otherwise.

operator entity()

constexpr co_ecs::const_entity_ref::operator entity ( ) const

inlineconstexprnoexcept

Converts this const_entity_ref to its underlying entity.

This conversion operator allows const_entity_ref to be treated as its underlying entity type directly. Useful in contexts where the entity's identifier is needed without explicit method calls.

Returns

entity The underlying entity associated with this const_entity_ref.

visit()

constexpr auto co_ecs::const_entity_ref::visit ( auto && func ) const

inlineconstexpr

Visit all components of an entity and apply a function to them (const version).

This function visits all components associated with an entity in the registry and applies the provided function to each component. This version is const and can be used in const contexts.

Parameters

func	A callable object (function, lambda, etc.) that will be applied to each component.

Example

entity.visit([](const component_meta& meta, const void* ptr) { std::cout << meta.type->name << '\n'; });

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

• include/co_ecs/entity_ref.hpp