entt::basic_runtime_view< Entity > Class Template Reference

Runtime view. More...

#include <runtime_view.hpp>

Public Types
using	entity_type = Entity
	Underlying entity identifier.
using	size_type = std::size_t
	Unsigned integer type.
using	iterator_type = iterator
	Input iterator type.

Public Member Functions
size_type	size () const ENTT_NOEXCEPT
	Estimates the number of entities that have the given components. More...
bool	empty () const ENTT_NOEXCEPT
	Checks if the view is definitely empty. More...
iterator_type	begin () const ENTT_NOEXCEPT
	Returns an iterator to the first entity that has the given components. More...
iterator_type	end () const ENTT_NOEXCEPT
	Returns an iterator that is past the last entity that has the given components. More...
bool	contains (const entity_type entt) const ENTT_NOEXCEPT
	Checks if a view contains an entity. More...
template<typename Func >
void	each (Func func) const
	Iterates entities and applies the given function object to them. More...

Friends
class	basic_registry< Entity >
	A registry is allowed to create views.

Detailed Description

template<typename Entity>
class entt::basic_runtime_view< Entity >

Runtime view.

Runtime views iterate over those entities that have at least all the given components in their bags. During initialization, a runtime view looks at the number of entities available for each component and picks up a reference to the smallest set of candidate entities in order to get a performance boost when iterate.
Order of elements during iterations are highly dependent on the order of the underlying data structures. See sparse_set and its specializations for more details.

Important

Iterators aren't invalidated if:

• New instances of the given components are created and assigned to entities.
• The entity currently pointed is modified (as an example, if one of the given components is removed from the entity to which the iterator points).
• The entity currently pointed is destroyed.

In all the other cases, modifying the pools of the given components in any way invalidates all the iterators and using them results in undefined behavior.

Note

Views share references to the underlying data structures of the registry that generated them. Therefore any change to the entities and to the components made by means of the registry are immediately reflected by the views, unless a pool was missing when the view was built (in this case, the view won't have a valid reference and won't be updated accordingly).

Warning

Lifetime of a view must overcome the one of the registry that generated it. In any other case, attempting to use a view results in undefined behavior.

Template Parameters

Entity

A valid entity type (see entt_traits for more details).

Definition at line 21 of file fwd.hpp.

Member Function Documentation

begin()

template<typename Entity >

iterator_type entt::basic_runtime_view< Entity >::begin ( ) const

inline

Returns an iterator to the first entity that has the given components.

The returned iterator points to the first entity that has the given components. If the view is empty, the returned iterator will be equal to end().

Note

Input iterators stay true to the order imposed to the underlying data structures.

Returns

An iterator to the first entity that has the given components.

Definition at line 179 of file runtime_view.hpp.

contains()

template<typename Entity >

bool entt::basic_runtime_view< Entity >::contains ( const entity_type  entt ) const

inline

Checks if a view contains an entity.

Parameters

entt	A valid entity identifier.

Returns

True if the view contains the given entity, false otherwise.

Definition at line 222 of file runtime_view.hpp.

each()

template<typename Entity >

template<typename Func >

void entt::basic_runtime_view< Entity >::each ( Func  func ) const

inline

Iterates entities and applies the given function object to them.

The function object is invoked for each entity. It is provided only with the entity itself. To get the components, users can use the registry with which the view was built.
The signature of the function should be equivalent to the following:

void(const entity_type);

Template Parameters

Func	Type of the function object to invoke.

Parameters

func	A valid function object.

Definition at line 244 of file runtime_view.hpp.

empty()

template<typename Entity >

bool entt::basic_runtime_view< Entity >::empty ( ) const

inline

Checks if the view is definitely empty.

Returns

True if the view is definitely empty, false otherwise.

Definition at line 161 of file runtime_view.hpp.

end()

template<typename Entity >

iterator_type entt::basic_runtime_view< Entity >::end ( ) const

inline

Returns an iterator that is past the last entity that has the given components.

The returned iterator points to the entity following the last entity that has the given components. Attempting to dereference the returned iterator results in undefined behavior.

Note

Input iterators stay true to the order imposed to the underlying data structures.

Returns

An iterator to the entity following the last entity that has the given components.

Definition at line 206 of file runtime_view.hpp.

size()

template<typename Entity >

size_type entt::basic_runtime_view< Entity >::size ( ) const

inline

Estimates the number of entities that have the given components.

Returns

Estimated number of entities that have the given components.

Definition at line 153 of file runtime_view.hpp.

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

• src/entt/entity/fwd.hpp
• src/entt/entity/runtime_view.hpp