#include <core/ecs/system/arguments/query.hpp>
template<typename... Ts>
cubos::core::ecs::Query class

System argument which holds the result of a query over all entities in world which match the given arguments.

Template parameters
Ts Argument types.

An example of a valid query is:

Query<Position&, const Velocity&, Opt<Rotation&>, Opt<const Scale&>>

This query will return all entities with a Position and Velocity component. Accessors to Rotation and Scale components are also passed but may be null if the component is not present in the entity. Whenever mutability is not needed, const should be used.

Constructors, destructors, conversion operators

Query(typename QueryData<Ts...>::View view)
Constructs.

Public functions

auto begin() -> Iterator
Returns an iterator pointing to the first query match.
auto end() -> Iterator
Returns an out of bounds iterator representing the end of the query matches.
auto pin(int target, Entity entity) -> Query
Returns a new query equal to this one but with the given target pinned to the given entity.
auto at(Entity entity) -> memory::Opt<std::tuple<Ts...>>
Accesses the match for the given entity, if there is one.
auto at(Entity firstEntity, Entity secondEntity) -> memory::Opt<std::tuple<Ts...>>
Accesses the match for the given entities, if there is one.
auto first() -> memory::Opt<std::tuple<Ts...>>
Returns the first match of the query, if there's any.
auto empty() -> bool
Returns whether the query is empty.

Function documentation

template<typename... Ts>
cubos::core::ecs::Query<Ts>::Query(typename QueryData<Ts...>::View view)

Constructs.

Parameters
view Query data view.

template<typename... Ts>
Iterator cubos::core::ecs::Query<Ts>::begin()

Returns an iterator pointing to the first query match.

Returns Iterator.

template<typename... Ts>
Iterator cubos::core::ecs::Query<Ts>::end()

Returns an out of bounds iterator representing the end of the query matches.

Returns Iterator.

template<typename... Ts>
Query cubos::core::ecs::Query<Ts>::pin(int target, Entity entity)

Returns a new query equal to this one but with the given target pinned to the given entity.

Parameters
target Target index.
entity Entity.
Returns Query.

Effectively this filters out all matches where the given target isn't the given entity.

template<typename... Ts>
memory::Opt<std::tuple<Ts...>> cubos::core::ecs::Query<Ts>::at(Entity entity)

Accesses the match for the given entity, if there is one.

Parameters
entity Entity.
Returns Requested components, or nothing if the entity does not match the query.

template<typename... Ts>
memory::Opt<std::tuple<Ts...>> cubos::core::ecs::Query<Ts>::at(Entity firstEntity, Entity secondEntity)

Accesses the match for the given entities, if there is one.

Parameters
firstEntity Entity for the first target.
secondEntity Entity for the second target.
Returns Requested data, or nothing if the entities do not match the query.

template<typename... Ts>
memory::Opt<std::tuple<Ts...>> cubos::core::ecs::Query<Ts>::first()

Returns the first match of the query, if there's any.

Returns Requested data, or nothing if there are no matches.

template<typename... Ts>
bool cubos::core::ecs::Query<Ts>::empty()

Returns whether the query is empty.

Returns True if the query is empty, false otherwise.