vecs::Query< Components > Class Template Reference

Represents a query for components within the ECS world. More...

#include <vecs.h>

Classes
class	Iterator
	Iterator for iterating over entities matching the query. More...
struct	Record
	A container for a single record and its components, as a result of a query. More...
struct	Single
	A container for a single entity and its components, as a result of a query. More...

Public Types
template<typename T >
using	QueryTypeTraits = _traits::query::QueryTypeTraits<T>
template<typename T >
using	ComponentStorageType = typename QueryTypeTraits<T>::StorageType
using	QueryComponents

Public Member Functions
	Query (World *world)
	Constructs a Query to search for entities with specified components.
Iterator	begin ()
	Returns an iterator to the beginning of the query results.
Iterator	end ()
	Returns an iterator to the end of the query results.
Record	get (Entity entity)
	Retrieves the components of an entity matching the query.
Record	get_single ()
	Retrieves the components of a single entity matching the query.

Static Public Member Functions
static ComponentMask	compute_mask ()

Detailed Description

template<typename... Components>
class vecs::Query< Components >

Represents a query for components within the ECS world.

This class provides an interface for querying entities that match a set of components. It allows iteration over matching entities and provides methods to retrieve individual results.

Template Parameters

Components

The types of components to be queried.

Member Typedef Documentation

QueryComponents

template<typename... Components>

using vecs::Query< Components >::QueryComponents

Initial value:

 
        std::vector<std::tuple<ComponentStorageType<Components>...>>

Constructor & Destructor Documentation

Query()

template<typename... Components>

vecs::Query< Components >::Query ( World * world )

inline

Constructs a Query to search for entities with specified components.

Parameters

world

Pointer to the ECS world containing the entities and components.

Member Function Documentation

begin()

template<typename... Components>

Iterator vecs::Query< Components >::begin ( )

inline

Returns an iterator to the beginning of the query results.

Returns

An iterator to the beginning of the entities that match the query.

end()

template<typename... Components>

Iterator vecs::Query< Components >::end ( )

inline

Returns an iterator to the end of the query results.

Returns

An iterator to the end of the entities that match the query.

get()

template<typename... Components>

Record vecs::Query< Components >::get ( Entity entity )

inline

Retrieves the components of an entity matching the query.

Parameters

entity

The entity to retrieve the components for.

Returns

A single Record containing the entity's components, or an invalid Record if the entity does not match the query.

Example usage:

auto e = world.spawn().insert(123, 321.f);
world.add_system([&e](Query<int, Optional<float>>& query) {
    Record record = query.get(e);
    if (record) {
        auto [i, maybe_f] = *record;
        printf("The record int component = %i\n", i);
        if (maybe_f) {
            printf("The record float component = %f\n", *maybe_f);
        }
        else {
            printf("The record does not have a float component\n");
        }
    }
});

get_single()

template<typename... Components>

Record vecs::Query< Components >::get_single ( )

inline

Retrieves the components of a single entity matching the query.

This method is intended to be used with queries that are expected to match exactly one entity. If the query does not match exactly one entity, an invalid Record is returned.

Returns

A single Record containing the matched component, or an invalid Record if no components or multiple components match the query.

Example usage:

auto e = world.spawn().insert(123, 321.f);
world.add_system([](Query<Entity, int, float>& query) {
    if (auto record = query.get_single()) {
        auto [e, i, f] = *record;
        printf("A single entity %zu contains an int and float component = %i, %f\n", e, i, f);
    }
});

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

• vecs.h