View pack. More...

#include <view_pack.hpp>

Public Types
using	entity_type = std::common_type_t< typename Head::entity_type, typename Tail::entity_type... >
	Underlying entity identifier.

using	size_type = std::common_type_t< typename Head::size_type, typename Tail::size_type... >
	Underlying entity identifier.

using	iterator = view_pack_iterator< typename Head::iterator >
	Input iterator type.

using	reverse_iterator = view_pack_iterator< typename Head::reverse_iterator >
	Reversed iterator type.

Public Member Functions
	view_pack (const Head &first, const Tail &... last)
	Constructs a pack from a bunch of views. More...

iterator	begin () const noexcept
	Returns an iterator to the first entity of the pack. More...

iterator	end () const noexcept
	Returns an iterator that is past the last entity of the pack. More...

reverse_iterator	rbegin () const
	Returns an iterator to the first entity of the pack. More...

reverse_iterator	rend () const
	Returns an iterator that is past the last entity of the reversed pack. More...

entity_type	front () const
	Returns the first entity of the pack, if any. More...

entity_type	back () const
	Returns the last entity of the pack, if any. More...

iterator	find (const entity_type entt) const
	Finds an entity. More...

bool	contains (const entity_type entt) const
	Checks if a pack contains an entity. More...

template<typename... Comp>
decltype(auto)	get ([[maybe_unused]] const entity_type entt) const
	Returns the components assigned to the given entity. More...

template<typename Func >
void	each (Func func) const
	Iterates entities and components and applies the given function object to them. More...

iterable_view_pack	each () const noexcept
	Returns an iterable object to use to visit the pack. More...

std::tuple< Head, Tail... >	pack () const noexcept
	Returns a copy of the views stored by the pack. More...

template<typename... Args>
auto	operator\| (const basic_view< Args... > &other) const
	Appends a view to a pack. More...

template<typename... Pack>
auto	operator\| (const view_pack< Pack... > &other) const
	Appends a pack and therefore all its views to another pack. More...

Detailed Description

template<typename Head, typename... Tail>
class entt::view_pack< Head, Tail >

View pack.

The view pack allows users to combine multiple views into a single iterable object, while also giving them full control over which view should lead the iteration.
This class returns all and only the entities present in all views. Its intended primary use is for custom storage and views, but it can also be very convenient in everyday use.

Template Parameters

Head	Type of the leading view of the pack.
Tail	Types of all other views of the pack.

Definition at line 31 of file view_pack.hpp.

Constructor & Destructor Documentation

◆ view_pack()

template<typename Head , typename... Tail>

entt::view_pack< Head, Tail >::view_pack	(	const Head &	first,
		const Tail &...	last
	)

inline

Constructs a pack from a bunch of views.

Parameters

first	A reference to the leading view for the pack.
last	References to the other views to use to construct the pack.

Definition at line 188 of file view_pack.hpp.

Member Function Documentation

◆ back()

template<typename Head , typename... Tail>

entity_type entt::view_pack< Head, Tail >::back ( ) const

inline

Returns the last entity of the pack, if any.

Returns: The last entity of the pack if one exists, the null entity otherwise.

Definition at line 260 of file view_pack.hpp.

◆ begin()

template<typename Head , typename... Tail>

iterator entt::view_pack< Head, Tail >::begin ( ) const

inlinenoexcept

Returns an iterator to the first entity of the pack.

The returned iterator points to the first entity of the pack. If the pack is empty, the returned iterator will be equal to end().

Returns: An iterator to the first entity of the pack.

Definition at line 201 of file view_pack.hpp.

◆ contains()

template<typename Head , typename... Tail>

bool entt::view_pack< Head, Tail >::contains ( const entity_type entt ) const

inline

Checks if a pack contains an entity.

Parameters

entt	A valid entity identifier.

Returns: True if the pack contains the given entity, false otherwise.

Definition at line 281 of file view_pack.hpp.

◆ each() [1/2]

template<typename Head , typename... Tail>

iterable_view_pack entt::view_pack< Head, Tail >::each ( ) const

inlinenoexcept

Returns an iterable object to use to visit the pack.

The iterable object returns tuples that contain the current entity and a set of references to its non-empty components. The constness of the components is as requested.

Note: Empty types aren't explicitly instantiated and therefore they are never returned during iterations.

Returns: An iterable object to use to visit the pack.

Definition at line 364 of file view_pack.hpp.

◆ each() [2/2]

template<typename Head , typename... Tail>

template<typename Func >

void entt::view_pack< Head, Tail >::each ( Func func ) const

inline

Iterates entities and components and applies the given function object to them.

The function object is invoked for each entity. It is provided with the entity itself and a set of references to non-empty components. The constness of the components is as requested.
The signature of the function must be equivalent to one of the following forms:

void(const entity_type, Type &...);

void(Type &...);

Note: Empty types aren't explicitly instantiated and therefore they are never returned during iterations.

Template Parameters

Func	Type of the function object to invoke.

Parameters

func	A valid function object.

Definition at line 337 of file view_pack.hpp.

◆ end()

template<typename Head , typename... Tail>

iterator entt::view_pack< Head, Tail >::end ( ) const

inlinenoexcept

Returns an iterator that is past the last entity of the pack.

The returned iterator points to the entity following the last entity of the pack. Attempting to dereference the returned iterator results in undefined behavior.

Returns: An iterator to the entity following the last entity of the pack.

Definition at line 214 of file view_pack.hpp.

◆ find()

template<typename Head , typename... Tail>

iterator entt::view_pack< Head, Tail >::find ( const entity_type entt ) const

inline

Finds an entity.

Parameters

entt	A valid entity identifier.

Returns: An iterator to the given entity if it's found, past the end iterator otherwise.

Definition at line 271 of file view_pack.hpp.

◆ front()

template<typename Head , typename... Tail>

entity_type entt::view_pack< Head, Tail >::front ( ) const

inline

Returns the first entity of the pack, if any.

Returns: The first entity of the pack if one exists, the null entity otherwise.

Definition at line 250 of file view_pack.hpp.

◆ get()

template<typename Head , typename... Tail>

template<typename... Comp>

decltype(auto) entt::view_pack< Head, Tail >::get ( [[maybe_unused] ] const entity_type entt ) const

inline

Returns the components assigned to the given entity.

Prefer this function instead of registry::get during iterations. It has far better performance than its counterpart.

Warning: Attempting to use an invalid component type results in a compilation error. Attempting to use an entity that doesn't belong to the pack results in undefined behavior.

Template Parameters

Comp	Types of components to get.

Parameters

entt	A valid entity identifier.

Returns: The components assigned to the entity.

Definition at line 301 of file view_pack.hpp.

◆ operator|() [1/2]

template<typename Head , typename... Tail>

template<typename... Args>

auto entt::view_pack< Head, Tail >::operator| ( const basic_view< Args... > & other ) const

inline

Appends a view to a pack.

Template Parameters

Args	View template arguments.

Parameters

other A reference to a view to append to the pack.

Returns: The extended pack.

Definition at line 383 of file view_pack.hpp.

◆ operator|() [2/2]

template<typename Head , typename... Tail>

template<typename... Pack>

auto entt::view_pack< Head, Tail >::operator| ( const view_pack< Pack... > & other ) const

inline

Appends a pack and therefore all its views to another pack.

Template Parameters

Pack	Types of views of the pack to append.

Parameters

other A reference to the pack to append.

Returns: The extended pack.

Definition at line 394 of file view_pack.hpp.

◆ pack()

template<typename Head , typename... Tail>

std::tuple<Head, Tail...> entt::view_pack< Head, Tail >::pack ( ) const

inlinenoexcept

Returns a copy of the views stored by the pack.

Returns: A copy of the views stored by the pack.

Definition at line 372 of file view_pack.hpp.

◆ rbegin()

template<typename Head , typename... Tail>

reverse_iterator entt::view_pack< Head, Tail >::rbegin ( ) const

inline

Returns an iterator to the first entity of the pack.

The returned iterator points to the first entity of the reversed pack. If the pack is empty, the returned iterator will be equal to rend().

Returns: An iterator to the first entity of the pack.

Definition at line 226 of file view_pack.hpp.

◆ rend()

template<typename Head , typename... Tail>

reverse_iterator entt::view_pack< Head, Tail >::rend ( ) const

inline

Returns an iterator that is past the last entity of the reversed pack.

The returned iterator points to the entity following the last entity of the reversed pack. Attempting to dereference the returned iterator results in undefined behavior.

Returns: An iterator to the entity following the last entity of the reversed pack.

Definition at line 241 of file view_pack.hpp.

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

src/entt/entity/view_pack.hpp

Public Types

Public Member Functions

Detailed Description

template<typename Head, typename... Tail> class entt::view_pack< Head, Tail >

Constructor & Destructor Documentation

◆ view_pack()

Member Function Documentation

◆ back()

◆ begin()

◆ contains()

◆ each() [1/2]

◆ each() [2/2]

◆ end()

◆ find()

◆ front()

◆ get()

◆ operator|() [1/2]

◆ operator|() [2/2]

◆ pack()

◆ rbegin()

◆ rend()

template<typename Head, typename... Tail>
class entt::view_pack< Head, Tail >