Trait HierarchyQueryExt

pub trait HierarchyQueryExt<'w, 's, D: QueryData, F: QueryFilter> {
    // Required methods
    fn parent(&'w self, entity: Entity) -> Option<Entity>
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>;
    fn children(&'w self, entity: Entity) -> &'w [Entity]
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>;
    fn root_ancestor(&'w self, entity: Entity) -> Entity
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>;
    fn iter_leaves(
        &'w self,
        entity: Entity,
    ) -> impl Iterator<Item = Entity> + 'w
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>;
    fn iter_siblings(&'w self, entity: Entity) -> impl Iterator<Item = Entity>
       where D::ReadOnly: WorldQuery<Item<'w> = (Option<&'w Parent>, Option<&'w Children>)>;
    fn iter_descendants(
        &'w self,
        entity: Entity,
    ) -> DescendantIter<'w, 's, D, F> 
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>;
    fn iter_descendants_depth_first(
        &'w self,
        entity: Entity,
    ) -> DescendantDepthFirstIter<'w, 's, D, F> 
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>;
    fn iter_ancestors(&'w self, entity: Entity) -> AncestorIter<'w, 's, D, F> 
       where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>;
}

An extension trait for Query that adds hierarchy related methods.

Required Methods

fn parent(&'w self, entity: Entity) -> Option<Entity>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

Returns the parent Entity of the given entity, if any.

fn children(&'w self, entity: Entity) -> &'w [Entity]

where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

Returns a slice over the Children of the given entity.

This may be empty if the entity has no children.

fn root_ancestor(&'w self, entity: Entity) -> Entity

where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

Returns the topmost ancestor of the given entity.

This may be the entity itself if it has no parent.

fn iter_leaves(&'w self, entity: Entity) -> impl Iterator<Item = Entity> + 'w

where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

Returns an Iterator of Entitys over the leaves of the hierarchy that are underneath this entity.

Only entities which have no children are considered leaves. This will not include the entity itself, and will not include any entities which are not descendants of the entity, even if they are leaves in the same hierarchical tree.

Traverses the hierarchy depth-first.

fn iter_siblings(&'w self, entity: Entity) -> impl Iterator<Item = Entity>

where D::ReadOnly: WorldQuery<Item<'w> = (Option<&'w Parent>, Option<&'w Children>)>,

Returns an Iterator of Entitys over the entitys immediate siblings, who share the same parent.

The entity itself is not included in the iterator.

fn iter_descendants(&'w self, entity: Entity) -> DescendantIter<'w, 's, D, F>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

Returns an Iterator of Entitys over all of entitys descendants.

Can only be called on a Query of Children (i.e. Query<&Children>).

Traverses the hierarchy breadth-first and does not include the entity itself.

Examples

fn system(entity: Single<Entity, With<Marker>>, children_query: Query<&Children>) {
    for descendant in children_query.iter_descendants(*entity) {
        // Do something!
    }
}

fn iter_descendants_depth_first( &'w self, entity: Entity, ) -> DescendantDepthFirstIter<'w, 's, D, F>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

Returns an Iterator of Entitys over all of entitys descendants.

Can only be called on a Query of Children (i.e. Query<&Children>).

This is a depth-first alternative to HierarchyQueryExt::iter_descendants.

fn iter_ancestors(&'w self, entity: Entity) -> AncestorIter<'w, 's, D, F>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

Returns an Iterator of Entitys over all of entitys ancestors.

Does not include the entity itself. Can only be called on a Query of Parent (i.e. Query<&Parent>).

Examples

fn system(entity: Single<Entity, With<Marker>>, parent_query: Query<&Parent>) {
    for ancestor in parent_query.iter_ancestors(*entity) {
        // Do something!
    }
}

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<'w, 's, D: QueryData, F: QueryFilter> HierarchyQueryExt<'w, 's, D, F> for Query<'w, 's, D, F>

fn parent(&'w self, entity: Entity) -> Option<Entity>

where <D as QueryData>::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

fn children(&'w self, entity: Entity) -> &'w [Entity]

where <D as QueryData>::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

fn root_ancestor(&'w self, entity: Entity) -> Entity

where <D as QueryData>::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

fn iter_leaves(&'w self, entity: Entity) -> impl Iterator<Item = Entity>

where <D as QueryData>::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

fn iter_siblings(&'w self, entity: Entity) -> impl Iterator<Item = Entity>

where D::ReadOnly: WorldQuery<Item<'w> = (Option<&'w Parent>, Option<&'w Children>)>,

fn iter_descendants(&'w self, entity: Entity) -> DescendantIter<'w, 's, D, F>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

fn iter_descendants_depth_first( &'w self, entity: Entity, ) -> DescendantDepthFirstIter<'w, 's, D, F>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Children>,

fn iter_ancestors(&'w self, entity: Entity) -> AncestorIter<'w, 's, D, F>

where D::ReadOnly: WorldQuery<Item<'w> = &'w Parent>,

Implementors