Struct HashMap 

pub struct HashMap<K, V, S = FixedHasher>(/* private fields */);

New-type for HashMap with FixedHasher as the default hashing provider. Can be trivially converted to and from a hashbrown HashMap using From.

A new-type is used instead of a type alias due to critical methods like new being incompatible with Bevy’s choice of default hasher.

Unlike hashbrown::HashMap, HashMap defaults to FixedHasher instead of RandomState. This provides determinism by default with an acceptable compromise to denial of service resistance in the context of a game engine.

Implementations

impl<K, V> HashMap<K, V>

pub const fn new() -> HashMap<K, V>

Creates an empty HashMap.

Refer to new for further details.

Examples

// Creates a HashMap with zero capacity.
let map = HashMap::new();

pub fn with_capacity(capacity: usize) -> HashMap<K, V>

Creates an empty HashMap with the specified capacity.

Refer to with_capacity for further details.

Examples

// Creates a HashMap with capacity for at least 5 entries.
let map = HashMap::with_capacity(5);

impl<K, V, S> HashMap<K, V, S>

pub const fn with_hasher(hash_builder: S) -> HashMap<K, V, S>

Creates an empty HashMap which will use the given hash builder to hash keys.

Refer to with_hasher for further details.

Examples

// Creates a HashMap with the provided hasher.
let map = HashMap::with_hasher(SomeHasher);

pub fn with_capacity_and_hasher( capacity: usize, hash_builder: S, ) -> HashMap<K, V, S>

Creates an empty HashMap with the specified capacity, using hash_builder to hash the keys.

Refer to with_capacity_and_hasher for further details.

Examples

// Creates a HashMap with capacity for 5 entries and the provided hasher.
let map = HashMap::with_capacity_and_hasher(5, SomeHasher);

pub fn hasher(&self) -> &S

Returns a reference to the map’s BuildHasher, or S parameter.

Refer to hasher for further details.

pub fn capacity(&self) -> usize

Returns the number of elements the map can hold without reallocating.

Refer to capacity for further details.

Examples

let map = HashMap::with_capacity(5);

assert!(map.capacity() >= 5);

pub fn keys(&self) -> Keys<'_, K, V>

An iterator visiting all keys in arbitrary order. The iterator element type is &'a K.

Refer to keys for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for key in map.keys() {
    // foo, bar, baz
    // Note that the above order is not guaranteed
}

Examples found in repository

examples/ui/scroll.rs (line 43)

fn send_scroll_events(
    mut mouse_wheel_reader: MessageReader<MouseWheel>,
    hover_map: Res<HoverMap>,
    keyboard_input: Res<ButtonInput<KeyCode>>,
    mut commands: Commands,
) {
    for mouse_wheel in mouse_wheel_reader.read() {
        let mut delta = -Vec2::new(mouse_wheel.x, mouse_wheel.y);

        if mouse_wheel.unit == MouseScrollUnit::Line {
            delta *= LINE_HEIGHT;
        }

        if keyboard_input.any_pressed([KeyCode::ControlLeft, KeyCode::ControlRight]) {
            std::mem::swap(&mut delta.x, &mut delta.y);
        }

        for pointer_map in hover_map.values() {
            for entity in pointer_map.keys().copied() {
                commands.trigger(Scroll { entity, delta });
            }
        }
    }
}

pub fn values(&self) -> Values<'_, K, V>

An iterator visiting all values in arbitrary order. The iterator element type is &'a V.

Refer to values for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for key in map.values() {
    // 0, 1, 2
    // Note that the above order is not guaranteed
}

Examples found in repository

tests/ecs/ambiguity_detection.rs (line 59)

    fn total(&self) -> usize {
        self.values().sum()
    }

examples/ui/scroll.rs (line 42)

fn send_scroll_events(
    mut mouse_wheel_reader: MessageReader<MouseWheel>,
    hover_map: Res<HoverMap>,
    keyboard_input: Res<ButtonInput<KeyCode>>,
    mut commands: Commands,
) {
    for mouse_wheel in mouse_wheel_reader.read() {
        let mut delta = -Vec2::new(mouse_wheel.x, mouse_wheel.y);

        if mouse_wheel.unit == MouseScrollUnit::Line {
            delta *= LINE_HEIGHT;
        }

        if keyboard_input.any_pressed([KeyCode::ControlLeft, KeyCode::ControlRight]) {
            std::mem::swap(&mut delta.x, &mut delta.y);
        }

        for pointer_map in hover_map.values() {
            for entity in pointer_map.keys().copied() {
                commands.trigger(Scroll { entity, delta });
            }
        }
    }
}

pub fn values_mut(&mut self) -> ValuesMut<'_, K, V>

An iterator visiting all values mutably in arbitrary order. The iterator element type is &'a mut V.

Refer to values for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for key in map.values_mut() {
    // 0, 1, 2
    // Note that the above order is not guaranteed
}

pub fn iter(&self) -> Iter<'_, K, V>

An iterator visiting all key-value pairs in arbitrary order. The iterator element type is (&'a K, &'a V).

Refer to iter for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for (key, value) in map.iter() {
    // ("foo", 0), ("bar", 1), ("baz", 2)
    // Note that the above order is not guaranteed
}

Examples found in repository

examples/testbed/full_ui.rs (line 455)

pub fn update_scroll_position(
    mut mouse_wheel_reader: MessageReader<MouseWheel>,
    hover_map: Res<HoverMap>,
    mut scrolled_node_query: Query<(&mut ScrollPosition, &ComputedNode), Without<Scrollbar>>,
    keyboard_input: Res<ButtonInput<KeyCode>>,
) {
    for mouse_wheel in mouse_wheel_reader.read() {
        let (mut dx, mut dy) = match mouse_wheel.unit {
            MouseScrollUnit::Line => (mouse_wheel.x * 20., mouse_wheel.y * 20.),
            MouseScrollUnit::Pixel => (mouse_wheel.x, mouse_wheel.y),
        };

        if keyboard_input.pressed(KeyCode::ShiftLeft) || keyboard_input.pressed(KeyCode::ShiftRight)
        {
            std::mem::swap(&mut dx, &mut dy);
        }

        for (_pointer, pointer_map) in hover_map.iter() {
            for (entity, _hit) in pointer_map.iter() {
                if let Ok((mut scroll_position, scroll_content)) =
                    scrolled_node_query.get_mut(*entity)
                {
                    let visible_size = scroll_content.size();
                    let content_size = scroll_content.content_size();

                    let range = (content_size.y - visible_size.y).max(0.)
                        * scroll_content.inverse_scale_factor;

                    scroll_position.x -= dx;
                    scroll_position.y = (scroll_position.y - dy).clamp(0., range);
                }
            }
        }
    }
}

pub fn iter_mut(&mut self) -> IterMut<'_, K, V>

An iterator visiting all key-value pairs in arbitrary order, with mutable references to the values. The iterator element type is (&'a K, &'a mut V).

Refer to iter_mut for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for (key, value) in map.iter_mut() {
    // ("foo", 0), ("bar", 1), ("baz", 2)
    // Note that the above order is not guaranteed
}

Examples found in repository

examples/3d/tonemapping.rs (line 380)

fn update_color_grading_settings(
    keys: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
    mut per_method_settings: ResMut<PerMethodSettings>,
    tonemapping: Single<&Tonemapping>,
    current_scene: Res<CurrentScene>,
    mut selected_parameter: ResMut<SelectedParameter>,
) {
    let color_grading = per_method_settings.settings.get_mut(*tonemapping).unwrap();
    let mut dt = time.delta_secs() * 0.25;
    if keys.pressed(KeyCode::ArrowLeft) {
        dt = -dt;
    }

    if keys.just_pressed(KeyCode::ArrowDown) {
        selected_parameter.next();
    }
    if keys.just_pressed(KeyCode::ArrowUp) {
        selected_parameter.prev();
    }
    if keys.pressed(KeyCode::ArrowLeft) || keys.pressed(KeyCode::ArrowRight) {
        match selected_parameter.value {
            0 => {
                color_grading.global.exposure += dt;
            }
            1 => {
                color_grading
                    .all_sections_mut()
                    .for_each(|section| section.gamma += dt);
            }
            2 => {
                color_grading
                    .all_sections_mut()
                    .for_each(|section| section.saturation += dt);
            }
            3 => {
                color_grading.global.post_saturation += dt;
            }
            _ => {}
        }
    }

    if keys.just_pressed(KeyCode::Space) {
        for (_, grading) in per_method_settings.settings.iter_mut() {
            *grading = ColorGrading::default();
        }
    }

    if keys.just_pressed(KeyCode::Enter) && current_scene.0 == 1 {
        for (mapper, grading) in per_method_settings.settings.iter_mut() {
            *grading = PerMethodSettings::basic_scene_recommendation(*mapper);
        }
    }
}

pub fn len(&self) -> usize

Returns the number of elements in the map.

Refer to len for further details.

Examples

let mut map = HashMap::new();

assert_eq!(map.len(), 0);

map.insert("foo", 0);

assert_eq!(map.len(), 1);

Examples found in repository

examples/stress_tests/many_lights.rs (line 178)

fn print_visible_light_count(
    time: Res<Time>,
    mut timer: Local<PrintingTimer>,
    visible: Query<&ExtractedPointLight>,
    global_light_meta: Res<GlobalClusterableObjectMeta>,
) {
    timer.0.tick(time.delta());

    if timer.0.just_finished() {
        info!(
            "Visible Lights: {}, Rendered Lights: {}",
            visible.iter().len(),
            global_light_meta.entity_to_index.len()
        );
    }
}

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Refer to is_empty for further details.

Examples

let mut map = HashMap::new();

assert!(map.is_empty());

map.insert("foo", 0);

assert!(!map.is_empty());

Examples found in repository

examples/2d/mesh2d_manual.rs (line 387)

pub fn queue_colored_mesh2d(
    transparent_draw_functions: Res<DrawFunctions<Transparent2d>>,
    colored_mesh2d_pipeline: Res<ColoredMesh2dPipeline>,
    mut pipelines: ResMut<SpecializedRenderPipelines<ColoredMesh2dPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    render_meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderColoredMesh2dInstances>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent2d>>,
    views: Query<(&RenderVisibleEntities, &ExtractedView, &Msaa)>,
) {
    if render_mesh_instances.is_empty() {
        return;
    }
    // Iterate each view (a camera is a view)
    for (visible_entities, view, msaa) in &views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&view.retained_view_entity)
        else {
            continue;
        };

        let draw_colored_mesh2d = transparent_draw_functions.read().id::<DrawColoredMesh2d>();

        let mesh_key = Mesh2dPipelineKey::from_msaa_samples(msaa.samples())
            | Mesh2dPipelineKey::from_hdr(view.hdr);

        // Queue all entities visible to that view
        for (render_entity, visible_entity) in visible_entities.iter::<Mesh2d>() {
            if let Some(mesh_instance) = render_mesh_instances.get(visible_entity) {
                let mesh2d_handle = mesh_instance.mesh_asset_id;
                let mesh2d_transforms = &mesh_instance.transforms;
                // Get our specialized pipeline
                let mut mesh2d_key = mesh_key;
                let Some(mesh) = render_meshes.get(mesh2d_handle) else {
                    continue;
                };
                mesh2d_key |= Mesh2dPipelineKey::from_primitive_topology(mesh.primitive_topology());

                let pipeline_id =
                    pipelines.specialize(&pipeline_cache, &colored_mesh2d_pipeline, mesh2d_key);

                let mesh_z = mesh2d_transforms.world_from_local.translation.z;
                transparent_phase.add(Transparent2d {
                    entity: (*render_entity, *visible_entity),
                    draw_function: draw_colored_mesh2d,
                    pipeline: pipeline_id,
                    // The 2d render items are sorted according to their z value before rendering,
                    // in order to get correct transparency
                    sort_key: FloatOrd(mesh_z),
                    // This material is not batched
                    batch_range: 0..1,
                    extra_index: PhaseItemExtraIndex::None,
                    extracted_index: usize::MAX,
                    indexed: mesh.indexed(),
                });
            }
        }
    }
}

pub fn drain(&mut self) -> Drain<'_, K, V>

Clears the map, returning all key-value pairs as an iterator. Keeps the allocated memory for reuse.

Refer to drain for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for (key, value) in map.drain() {
    // ("foo", 0), ("bar", 1), ("baz", 2)
    // Note that the above order is not guaranteed
}

assert!(map.is_empty());

pub fn retain<F>(&mut self, f: F)

where F: FnMut(&K, &mut V) -> bool,

Retains only the elements specified by the predicate. Keeps the allocated memory for reuse.

Refer to retain for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

map.retain(|key, value| *value == 2);

assert_eq!(map.len(), 1);

Examples found in repository

examples/shader_advanced/custom_render_phase.rs (line 490)

fn extract_camera_phases(
    mut stencil_phases: ResMut<ViewSortedRenderPhases<Stencil3d>>,
    cameras: Extract<Query<(Entity, &Camera), With<Camera3d>>>,
    mut live_entities: Local<HashSet<RetainedViewEntity>>,
) {
    live_entities.clear();
    for (main_entity, camera) in &cameras {
        if !camera.is_active {
            continue;
        }
        // This is the main camera, so we use the first subview index (0)
        let retained_view_entity = RetainedViewEntity::new(main_entity.into(), None, 0);

        stencil_phases.insert_or_clear(retained_view_entity);
        live_entities.insert(retained_view_entity);
    }

    // Clear out all dead views.
    stencil_phases.retain(|camera_entity, _| live_entities.contains(camera_entity));
}

pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, K, V, F>

where F: FnMut(&K, &mut V) -> bool,

Drains elements which are true under the given predicate, and returns an iterator over the removed items.

Refer to extract_if for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

let extracted = map
    .extract_if(|key, value| *value == 2)
    .collect::<Vec<_>>();

assert_eq!(map.len(), 2);
assert_eq!(extracted.len(), 1);

pub fn clear(&mut self)

Clears the map, removing all key-value pairs. Keeps the allocated memory for reuse.

Refer to clear for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

map.clear();

assert!(map.is_empty());

pub fn into_keys(self) -> IntoKeys<K, V>

Creates a consuming iterator visiting all the keys in arbitrary order. The map cannot be used after calling this. The iterator element type is K.

Refer to into_keys for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for key in map.into_keys() {
    // "foo", "bar", "baz"
    // Note that the above order is not guaranteed
}

pub fn into_values(self) -> IntoValues<K, V>

Creates a consuming iterator visiting all the values in arbitrary order. The map cannot be used after calling this. The iterator element type is V.

Refer to into_values for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

for key in map.into_values() {
    // 0, 1, 2
    // Note that the above order is not guaranteed
}

pub fn into_inner(self) -> HashMap<K, V, S>

Takes the inner HashMap out of this wrapper.

Examples

let map: HashMap<&'static str, usize> = HashMap::new();
let map: hashbrown::HashMap<&'static str, usize, _> = map.into_inner();

impl<K, V, S> HashMap<K, V, S>

where K: Eq + Hash, S: BuildHasher,

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted in the HashMap. The collection may reserve more space to avoid frequent reallocations.

Refer to reserve for further details.

Examples

let mut map = HashMap::with_capacity(5);

assert!(map.capacity() >= 5);

map.reserve(10);

assert!(map.capacity() - map.len() >= 10);

pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>

Tries to reserve capacity for at least additional more elements to be inserted in the given HashMap<K,V>. The collection may reserve more space to avoid frequent reallocations.

Refer to try_reserve for further details.

Examples

let mut map = HashMap::with_capacity(5);

assert!(map.capacity() >= 5);

map.try_reserve(10).expect("Out of Memory!");

assert!(map.capacity() - map.len() >= 10);

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of the map as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Refer to shrink_to_fit for further details.

Examples

let mut map = HashMap::with_capacity(5);

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

assert!(map.capacity() >= 5);

map.shrink_to_fit();

assert_eq!(map.capacity(), 3);

pub fn shrink_to(&mut self, min_capacity: usize)

Shrinks the capacity of the map with a lower limit. It will drop down no lower than the supplied limit while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Refer to shrink_to for further details.

pub fn entry(&mut self, key: K) -> Entry<'_, K, V, S>

Gets the given key’s corresponding entry in the map for in-place manipulation.

Refer to entry for further details.

Examples

let mut map = HashMap::new();

let value = map.entry("foo").or_insert(0);

Examples found in repository

examples/ecs/observers.rs (line 125)

fn on_add_mine(add: On<Add, Mine>, query: Query<&Mine>, mut index: ResMut<SpatialIndex>) {
    let mine = query.get(add.entity).unwrap();
    let tile = (
        (mine.pos.x / CELL_SIZE).floor() as i32,
        (mine.pos.y / CELL_SIZE).floor() as i32,
    );
    index.map.entry(tile).or_default().insert(add.entity);
}

// Remove despawned mines from our index
fn on_remove_mine(remove: On<Remove, Mine>, query: Query<&Mine>, mut index: ResMut<SpatialIndex>) {
    let mine = query.get(remove.entity).unwrap();
    let tile = (
        (mine.pos.x / CELL_SIZE).floor() as i32,
        (mine.pos.y / CELL_SIZE).floor() as i32,
    );
    index.map.entry(tile).and_modify(|set| {
        set.remove(&remove.entity);
    });
}

examples/3d/manual_material.rs (line 174)

    fn prepare_asset(
        source_asset: Self::SourceAsset,
        asset_id: AssetId<Self::SourceAsset>,
        (
            opaque_draw_functions,
            material_layout,
            asset_server,
            bind_group_allocators,
            render_material_bindings,
            gpu_images,
            image_material_sampler,
        ): &mut SystemParamItem<Self::Param>,
    ) -> std::result::Result<Self::ErasedAsset, PrepareAssetError<Self::SourceAsset>> {
        let material_layout = material_layout.0.clone();
        let draw_function_id = opaque_draw_functions.read().id::<DrawMaterial>();
        let bind_group_allocator = bind_group_allocators
            .get_mut(&TypeId::of::<ImageMaterial>())
            .unwrap();
        let Some(image) = gpu_images.get(&source_asset.image) else {
            return Err(PrepareAssetError::RetryNextUpdate(source_asset));
        };
        let unprepared = UnpreparedBindGroup {
            bindings: BindingResources(vec![
                (
                    0,
                    OwnedBindingResource::TextureView(
                        TextureViewDimension::D2,
                        image.texture_view.clone(),
                    ),
                ),
                (
                    1,
                    OwnedBindingResource::Sampler(
                        SamplerBindingType::NonFiltering,
                        image_material_sampler.0.clone(),
                    ),
                ),
            ]),
        };
        let binding = match render_material_bindings.entry(asset_id.into()) {
            Entry::Occupied(mut occupied_entry) => {
                bind_group_allocator.free(*occupied_entry.get());
                let new_binding =
                    bind_group_allocator.allocate_unprepared(unprepared, &material_layout);
                *occupied_entry.get_mut() = new_binding;
                new_binding
            }
            Entry::Vacant(vacant_entry) => *vacant_entry
                .insert(bind_group_allocator.allocate_unprepared(unprepared, &material_layout)),
        };

        let mut properties = MaterialProperties {
            material_layout: Some(material_layout),
            ..Default::default()
        };
        properties.add_draw_function(MaterialDrawFunction, draw_function_id);
        properties.add_shader(MaterialFragmentShader, asset_server.load(SHADER_ASSET_PATH));

        Ok(PreparedMaterial {
            binding,
            properties: Arc::new(properties),
        })
    }

pub fn entry_ref<'a, 'b, Q>( &'a mut self, key: &'b Q, ) -> EntryRef<'a, 'b, K, Q, V, S>

where Q: Hash + Equivalent<K> + ?Sized,

Gets the given key’s corresponding entry by reference in the map for in-place manipulation.

Refer to entry_ref for further details.

Examples

let mut map = HashMap::new();

let value = map.entry_ref("foo").or_insert(0);

pub fn get<Q>(&self, k: &Q) -> Option<&V>

where Q: Hash + Equivalent<K> + ?Sized,

Returns a reference to the value corresponding to the key.

Refer to get for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.get("foo"), Some(&0));

Examples found in repository

examples/ecs/immutable_components.rs (line 69)

    fn get_entity(&self, name: &'static str) -> Option<Entity> {
        self.name_to_entity.get(&Name(name)).copied()
    }

examples/ecs/observers.rs (line 206)

    fn get_nearby(&self, pos: Vec2) -> Vec<Entity> {
        let tile = (
            (pos.x / CELL_SIZE).floor() as i32,
            (pos.y / CELL_SIZE).floor() as i32,
        );
        let mut nearby = Vec::new();
        for x in -1..2 {
            for y in -1..2 {
                if let Some(mines) = self.map.get(&(tile.0 + x, tile.1 + y)) {
                    nearby.extend(mines.iter());
                }
            }
        }
        nearby
    }

examples/3d/tonemapping.rs (line 316)

fn toggle_tonemapping_method(
    keys: Res<ButtonInput<KeyCode>>,
    mut tonemapping: Single<&mut Tonemapping>,
    mut color_grading: Single<&mut ColorGrading>,
    per_method_settings: Res<PerMethodSettings>,
) {
    if keys.just_pressed(KeyCode::Digit1) {
        **tonemapping = Tonemapping::None;
    } else if keys.just_pressed(KeyCode::Digit2) {
        **tonemapping = Tonemapping::Reinhard;
    } else if keys.just_pressed(KeyCode::Digit3) {
        **tonemapping = Tonemapping::ReinhardLuminance;
    } else if keys.just_pressed(KeyCode::Digit4) {
        **tonemapping = Tonemapping::AcesFitted;
    } else if keys.just_pressed(KeyCode::Digit5) {
        **tonemapping = Tonemapping::AgX;
    } else if keys.just_pressed(KeyCode::Digit6) {
        **tonemapping = Tonemapping::SomewhatBoringDisplayTransform;
    } else if keys.just_pressed(KeyCode::Digit7) {
        **tonemapping = Tonemapping::TonyMcMapface;
    } else if keys.just_pressed(KeyCode::Digit8) {
        **tonemapping = Tonemapping::BlenderFilmic;
    }

    **color_grading = (*per_method_settings
        .settings
        .get::<Tonemapping>(&tonemapping)
        .as_ref()
        .unwrap())
    .clone();
}

examples/shader_advanced/custom_render_phase.rs (line 353)

    fn get_batch_data(
        (mesh_instances, _render_assets, mesh_allocator): &SystemParamItem<Self::Param>,
        (_entity, main_entity): (Entity, MainEntity),
    ) -> Option<(Self::BufferData, Option<Self::CompareData>)> {
        let RenderMeshInstances::CpuBuilding(ref mesh_instances) = **mesh_instances else {
            error!(
                "`get_batch_data` should never be called in GPU mesh uniform \
                building mode"
            );
            return None;
        };
        let mesh_instance = mesh_instances.get(&main_entity)?;
        let first_vertex_index =
            match mesh_allocator.mesh_vertex_slice(&mesh_instance.mesh_asset_id) {
                Some(mesh_vertex_slice) => mesh_vertex_slice.range.start,
                None => 0,
            };
        let mesh_uniform = {
            let mesh_transforms = &mesh_instance.transforms;
            let (local_from_world_transpose_a, local_from_world_transpose_b) =
                mesh_transforms.world_from_local.inverse_transpose_3x3();
            MeshUniform {
                world_from_local: mesh_transforms.world_from_local.to_transpose(),
                previous_world_from_local: mesh_transforms.previous_world_from_local.to_transpose(),
                lightmap_uv_rect: UVec2::ZERO,
                local_from_world_transpose_a,
                local_from_world_transpose_b,
                flags: mesh_transforms.flags,
                first_vertex_index,
                current_skin_index: u32::MAX,
                material_and_lightmap_bind_group_slot: 0,
                tag: 0,
                pad: 0,
            }
        };
        Some((mesh_uniform, None))
    }
}

impl GetFullBatchData for StencilPipeline {
    type BufferInputData = MeshInputUniform;

    fn get_index_and_compare_data(
        (mesh_instances, _, _): &SystemParamItem<Self::Param>,
        main_entity: MainEntity,
    ) -> Option<(NonMaxU32, Option<Self::CompareData>)> {
        // This should only be called during GPU building.
        let RenderMeshInstances::GpuBuilding(ref mesh_instances) = **mesh_instances else {
            error!(
                "`get_index_and_compare_data` should never be called in CPU mesh uniform building \
                mode"
            );
            return None;
        };
        let mesh_instance = mesh_instances.get(&main_entity)?;
        Some((
            mesh_instance.current_uniform_index,
            mesh_instance
                .should_batch()
                .then_some(mesh_instance.mesh_asset_id),
        ))
    }

    fn get_binned_batch_data(
        (mesh_instances, _render_assets, mesh_allocator): &SystemParamItem<Self::Param>,
        main_entity: MainEntity,
    ) -> Option<Self::BufferData> {
        let RenderMeshInstances::CpuBuilding(ref mesh_instances) = **mesh_instances else {
            error!(
                "`get_binned_batch_data` should never be called in GPU mesh uniform building mode"
            );
            return None;
        };
        let mesh_instance = mesh_instances.get(&main_entity)?;
        let first_vertex_index =
            match mesh_allocator.mesh_vertex_slice(&mesh_instance.mesh_asset_id) {
                Some(mesh_vertex_slice) => mesh_vertex_slice.range.start,
                None => 0,
            };

        Some(MeshUniform::new(
            &mesh_instance.transforms,
            first_vertex_index,
            mesh_instance.material_bindings_index.slot,
            None,
            None,
            None,
        ))
    }

    fn write_batch_indirect_parameters_metadata(
        indexed: bool,
        base_output_index: u32,
        batch_set_index: Option<NonMaxU32>,
        indirect_parameters_buffers: &mut UntypedPhaseIndirectParametersBuffers,
        indirect_parameters_offset: u32,
    ) {
        // Note that `IndirectParameters` covers both of these structures, even
        // though they actually have distinct layouts. See the comment above that
        // type for more information.
        let indirect_parameters = IndirectParametersCpuMetadata {
            base_output_index,
            batch_set_index: match batch_set_index {
                None => !0,
                Some(batch_set_index) => u32::from(batch_set_index),
            },
        };

        if indexed {
            indirect_parameters_buffers
                .indexed
                .set(indirect_parameters_offset, indirect_parameters);
        } else {
            indirect_parameters_buffers
                .non_indexed
                .set(indirect_parameters_offset, indirect_parameters);
        }
    }

    fn get_binned_index(
        _param: &SystemParamItem<Self::Param>,
        _query_item: MainEntity,
    ) -> Option<NonMaxU32> {
        None
    }
}

// When defining a phase, we need to extract it from the main world and add it to a resource
// that will be used by the render world. We need to give that resource all views that will use
// that phase
fn extract_camera_phases(
    mut stencil_phases: ResMut<ViewSortedRenderPhases<Stencil3d>>,
    cameras: Extract<Query<(Entity, &Camera), With<Camera3d>>>,
    mut live_entities: Local<HashSet<RetainedViewEntity>>,
) {
    live_entities.clear();
    for (main_entity, camera) in &cameras {
        if !camera.is_active {
            continue;
        }
        // This is the main camera, so we use the first subview index (0)
        let retained_view_entity = RetainedViewEntity::new(main_entity.into(), None, 0);

        stencil_phases.insert_or_clear(retained_view_entity);
        live_entities.insert(retained_view_entity);
    }

    // Clear out all dead views.
    stencil_phases.retain(|camera_entity, _| live_entities.contains(camera_entity));
}

// This is a very important step when writing a custom phase.
//
// This system determines which meshes will be added to the phase.
fn queue_custom_meshes(
    custom_draw_functions: Res<DrawFunctions<Stencil3d>>,
    mut pipelines: ResMut<SpecializedMeshPipelines<StencilPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    custom_draw_pipeline: Res<StencilPipeline>,
    render_meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderMeshInstances>,
    mut custom_render_phases: ResMut<ViewSortedRenderPhases<Stencil3d>>,
    mut views: Query<(&ExtractedView, &RenderVisibleEntities, &Msaa)>,
    has_marker: Query<(), With<DrawStencil>>,
) {
    for (view, visible_entities, msaa) in &mut views {
        let Some(custom_phase) = custom_render_phases.get_mut(&view.retained_view_entity) else {
            continue;
        };
        let draw_custom = custom_draw_functions.read().id::<DrawMesh3dStencil>();

        // Create the key based on the view.
        // In this case we only care about MSAA and HDR
        let view_key = MeshPipelineKey::from_msaa_samples(msaa.samples())
            | MeshPipelineKey::from_hdr(view.hdr);

        let rangefinder = view.rangefinder3d();
        // Since our phase can work on any 3d mesh we can reuse the default mesh 3d filter
        for (render_entity, visible_entity) in visible_entities.iter::<Mesh3d>() {
            // We only want meshes with the marker component to be queued to our phase.
            if has_marker.get(*render_entity).is_err() {
                continue;
            }
            let Some(mesh_instance) = render_mesh_instances.render_mesh_queue_data(*visible_entity)
            else {
                continue;
            };
            let Some(mesh) = render_meshes.get(mesh_instance.mesh_asset_id) else {
                continue;
            };

            // Specialize the key for the current mesh entity
            // For this example we only specialize based on the mesh topology
            // but you could have more complex keys and that's where you'd need to create those keys
            let mut mesh_key = view_key;
            mesh_key |= MeshPipelineKey::from_primitive_topology(mesh.primitive_topology());

            let pipeline_id = pipelines.specialize(
                &pipeline_cache,
                &custom_draw_pipeline,
                mesh_key,
                &mesh.layout,
            );
            let pipeline_id = match pipeline_id {
                Ok(id) => id,
                Err(err) => {
                    error!("{}", err);
                    continue;
                }
            };
            let distance = rangefinder.distance_translation(&mesh_instance.translation);
            // At this point we have all the data we need to create a phase item and add it to our
            // phase
            custom_phase.add(Stencil3d {
                // Sort the data based on the distance to the view
                sort_key: FloatOrd(distance),
                entity: (*render_entity, *visible_entity),
                pipeline: pipeline_id,
                draw_function: draw_custom,
                // Sorted phase items aren't batched
                batch_range: 0..1,
                extra_index: PhaseItemExtraIndex::None,
                indexed: mesh.indexed(),
            });
        }
    }
}

// Render label used to order our render graph node that will render our phase
#[derive(RenderLabel, Debug, Clone, Hash, PartialEq, Eq)]
struct CustomDrawPassLabel;

#[derive(Default)]
struct CustomDrawNode;
impl ViewNode for CustomDrawNode {
    type ViewQuery = (
        &'static ExtractedCamera,
        &'static ExtractedView,
        &'static ViewTarget,
        Option<&'static MainPassResolutionOverride>,
    );

    fn run<'w>(
        &self,
        graph: &mut RenderGraphContext,
        render_context: &mut RenderContext<'w>,
        (camera, view, target, resolution_override): QueryItem<'w, '_, Self::ViewQuery>,
        world: &'w World,
    ) -> Result<(), NodeRunError> {
        // First, we need to get our phases resource
        let Some(stencil_phases) = world.get_resource::<ViewSortedRenderPhases<Stencil3d>>() else {
            return Ok(());
        };

        // Get the view entity from the graph
        let view_entity = graph.view_entity();

        // Get the phase for the current view running our node
        let Some(stencil_phase) = stencil_phases.get(&view.retained_view_entity) else {
            return Ok(());
        };

        // Render pass setup
        let mut render_pass = render_context.begin_tracked_render_pass(RenderPassDescriptor {
            label: Some("stencil pass"),
            // For the purpose of the example, we will write directly to the view target. A real
            // stencil pass would write to a custom texture and that texture would be used in later
            // passes to render custom effects using it.
            color_attachments: &[Some(target.get_color_attachment())],
            // We don't bind any depth buffer for this pass
            depth_stencil_attachment: None,
            timestamp_writes: None,
            occlusion_query_set: None,
        });

        if let Some(viewport) =
            Viewport::from_viewport_and_override(camera.viewport.as_ref(), resolution_override)
        {
            render_pass.set_camera_viewport(&viewport);
        }

        // Render the phase
        // This will execute each draw functions of each phase items queued in this phase
        if let Err(err) = stencil_phase.render(&mut render_pass, world, view_entity) {
            error!("Error encountered while rendering the stencil phase {err:?}");
        }

        Ok(())
    }

examples/3d/occlusion_culling.rs (line 435)

    fn run<'w>(
        &self,
        _: &mut RenderGraphContext,
        render_context: &mut RenderContext<'w>,
        world: &'w World,
    ) -> Result<(), NodeRunError> {
        // Extract the buffers that hold the GPU indirect draw parameters from
        // the world resources. We're going to read those buffers to determine
        // how many meshes were actually drawn.
        let (Some(indirect_parameters_buffers), Some(indirect_parameters_mapping_buffers)) = (
            world.get_resource::<IndirectParametersBuffers>(),
            world.get_resource::<IndirectParametersStagingBuffers>(),
        ) else {
            return Ok(());
        };

        // Get the indirect parameters buffers corresponding to the opaque 3D
        // phase, since all our meshes are in that phase.
        let Some(phase_indirect_parameters_buffers) =
            indirect_parameters_buffers.get(&TypeId::of::<Opaque3d>())
        else {
            return Ok(());
        };

        // Grab both the buffers we're copying from and the staging buffers
        // we're copying to. Remember that we can't map the indirect parameters
        // buffers directly, so we have to copy their contents to a staging
        // buffer.
        let (
            Some(indexed_data_buffer),
            Some(indexed_batch_sets_buffer),
            Some(indirect_parameters_staging_data_buffer),
            Some(indirect_parameters_staging_batch_sets_buffer),
        ) = (
            phase_indirect_parameters_buffers.indexed.data_buffer(),
            phase_indirect_parameters_buffers
                .indexed
                .batch_sets_buffer(),
            indirect_parameters_mapping_buffers.data.as_ref(),
            indirect_parameters_mapping_buffers.batch_sets.as_ref(),
        )
        else {
            return Ok(());
        };

        // Copy from the indirect parameters buffers to the staging buffers.
        render_context.command_encoder().copy_buffer_to_buffer(
            indexed_data_buffer,
            0,
            indirect_parameters_staging_data_buffer,
            0,
            indexed_data_buffer.size(),
        );
        render_context.command_encoder().copy_buffer_to_buffer(
            indexed_batch_sets_buffer,
            0,
            indirect_parameters_staging_batch_sets_buffer,
            0,
            indexed_batch_sets_buffer.size(),
        );

        Ok(())
    }
}

/// Creates the staging buffers that we use to read back the indirect parameters
/// from the GPU to the CPU.
///
/// We read the indirect parameters from the GPU to the CPU in order to display
/// the number of meshes that were culled each frame.
///
/// We need these staging buffers because `wgpu` doesn't allow us to read the
/// contents of the indirect parameters buffers directly. We must first copy
/// them from the GPU to a staging buffer, and then read the staging buffer.
fn create_indirect_parameters_staging_buffers(
    mut indirect_parameters_staging_buffers: ResMut<IndirectParametersStagingBuffers>,
    indirect_parameters_buffers: Res<IndirectParametersBuffers>,
    render_device: Res<RenderDevice>,
) {
    let Some(phase_indirect_parameters_buffers) =
        indirect_parameters_buffers.get(&TypeId::of::<Opaque3d>())
    else {
        return;
    };

    // Fetch the indirect parameters buffers that we're going to copy from.
    let (Some(indexed_data_buffer), Some(indexed_batch_set_buffer)) = (
        phase_indirect_parameters_buffers.indexed.data_buffer(),
        phase_indirect_parameters_buffers
            .indexed
            .batch_sets_buffer(),
    ) else {
        return;
    };

    // Build the staging buffers. Make sure they have the same sizes as the
    // buffers we're copying from.
    indirect_parameters_staging_buffers.data =
        Some(render_device.create_buffer(&BufferDescriptor {
            label: Some("indexed data staging buffer"),
            size: indexed_data_buffer.size(),
            usage: BufferUsages::MAP_READ | BufferUsages::COPY_DST,
            mapped_at_creation: false,
        }));
    indirect_parameters_staging_buffers.batch_sets =
        Some(render_device.create_buffer(&BufferDescriptor {
            label: Some("indexed batch set staging buffer"),
            size: indexed_batch_set_buffer.size(),
            usage: BufferUsages::MAP_READ | BufferUsages::COPY_DST,
            mapped_at_creation: false,
        }));
}

examples/2d/mesh2d_manual.rs (line 404)

pub fn queue_colored_mesh2d(
    transparent_draw_functions: Res<DrawFunctions<Transparent2d>>,
    colored_mesh2d_pipeline: Res<ColoredMesh2dPipeline>,
    mut pipelines: ResMut<SpecializedRenderPipelines<ColoredMesh2dPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    render_meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderColoredMesh2dInstances>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent2d>>,
    views: Query<(&RenderVisibleEntities, &ExtractedView, &Msaa)>,
) {
    if render_mesh_instances.is_empty() {
        return;
    }
    // Iterate each view (a camera is a view)
    for (visible_entities, view, msaa) in &views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&view.retained_view_entity)
        else {
            continue;
        };

        let draw_colored_mesh2d = transparent_draw_functions.read().id::<DrawColoredMesh2d>();

        let mesh_key = Mesh2dPipelineKey::from_msaa_samples(msaa.samples())
            | Mesh2dPipelineKey::from_hdr(view.hdr);

        // Queue all entities visible to that view
        for (render_entity, visible_entity) in visible_entities.iter::<Mesh2d>() {
            if let Some(mesh_instance) = render_mesh_instances.get(visible_entity) {
                let mesh2d_handle = mesh_instance.mesh_asset_id;
                let mesh2d_transforms = &mesh_instance.transforms;
                // Get our specialized pipeline
                let mut mesh2d_key = mesh_key;
                let Some(mesh) = render_meshes.get(mesh2d_handle) else {
                    continue;
                };
                mesh2d_key |= Mesh2dPipelineKey::from_primitive_topology(mesh.primitive_topology());

                let pipeline_id =
                    pipelines.specialize(&pipeline_cache, &colored_mesh2d_pipeline, mesh2d_key);

                let mesh_z = mesh2d_transforms.world_from_local.translation.z;
                transparent_phase.add(Transparent2d {
                    entity: (*render_entity, *visible_entity),
                    draw_function: draw_colored_mesh2d,
                    pipeline: pipeline_id,
                    // The 2d render items are sorted according to their z value before rendering,
                    // in order to get correct transparency
                    sort_key: FloatOrd(mesh_z),
                    // This material is not batched
                    batch_range: 0..1,
                    extra_index: PhaseItemExtraIndex::None,
                    extracted_index: usize::MAX,
                    indexed: mesh.indexed(),
                });
            }
        }
    }
}

Additional examples can be found in:

• examples/ui/directional_navigation.rs

pub fn get_key_value<Q>(&self, k: &Q) -> Option<(&K, &V)>

where Q: Hash + Equivalent<K> + ?Sized,

Returns the key-value pair corresponding to the supplied key.

Refer to get_key_value for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.get_key_value("foo"), Some((&"foo", &0)));

pub fn get_key_value_mut<Q>(&mut self, k: &Q) -> Option<(&K, &mut V)>

where Q: Hash + Equivalent<K> + ?Sized,

Returns the key-value pair corresponding to the supplied key, with a mutable reference to value.

Refer to get_key_value_mut for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.get_key_value_mut("foo"), Some((&"foo", &mut 0)));

pub fn contains_key<Q>(&self, k: &Q) -> bool

where Q: Hash + Equivalent<K> + ?Sized,

Returns true if the map contains a value for the specified key.

Refer to contains_key for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert!(map.contains_key("foo"));

pub fn get_mut<Q>(&mut self, k: &Q) -> Option<&mut V>

where Q: Hash + Equivalent<K> + ?Sized,

Returns a mutable reference to the value corresponding to the key.

Refer to get_mut for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.get_mut("foo"), Some(&mut 0));

Examples found in repository

examples/3d/tonemapping.rs (line 345)

fn update_color_grading_settings(
    keys: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
    mut per_method_settings: ResMut<PerMethodSettings>,
    tonemapping: Single<&Tonemapping>,
    current_scene: Res<CurrentScene>,
    mut selected_parameter: ResMut<SelectedParameter>,
) {
    let color_grading = per_method_settings.settings.get_mut(*tonemapping).unwrap();
    let mut dt = time.delta_secs() * 0.25;
    if keys.pressed(KeyCode::ArrowLeft) {
        dt = -dt;
    }

    if keys.just_pressed(KeyCode::ArrowDown) {
        selected_parameter.next();
    }
    if keys.just_pressed(KeyCode::ArrowUp) {
        selected_parameter.prev();
    }
    if keys.pressed(KeyCode::ArrowLeft) || keys.pressed(KeyCode::ArrowRight) {
        match selected_parameter.value {
            0 => {
                color_grading.global.exposure += dt;
            }
            1 => {
                color_grading
                    .all_sections_mut()
                    .for_each(|section| section.gamma += dt);
            }
            2 => {
                color_grading
                    .all_sections_mut()
                    .for_each(|section| section.saturation += dt);
            }
            3 => {
                color_grading.global.post_saturation += dt;
            }
            _ => {}
        }
    }

    if keys.just_pressed(KeyCode::Space) {
        for (_, grading) in per_method_settings.settings.iter_mut() {
            *grading = ColorGrading::default();
        }
    }

    if keys.just_pressed(KeyCode::Enter) && current_scene.0 == 1 {
        for (mapper, grading) in per_method_settings.settings.iter_mut() {
            *grading = PerMethodSettings::basic_scene_recommendation(*mapper);
        }
    }
}

examples/shader_advanced/custom_shader_instancing.rs (line 138)

fn queue_custom(
    transparent_3d_draw_functions: Res<DrawFunctions<Transparent3d>>,
    custom_pipeline: Res<CustomPipeline>,
    mut pipelines: ResMut<SpecializedMeshPipelines<CustomPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderMeshInstances>,
    material_meshes: Query<(Entity, &MainEntity), With<InstanceMaterialData>>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent3d>>,
    views: Query<(&ExtractedView, &Msaa)>,
) {
    let draw_custom = transparent_3d_draw_functions.read().id::<DrawCustom>();

    for (view, msaa) in &views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&view.retained_view_entity)
        else {
            continue;
        };

        let msaa_key = MeshPipelineKey::from_msaa_samples(msaa.samples());

        let view_key = msaa_key | MeshPipelineKey::from_hdr(view.hdr);
        let rangefinder = view.rangefinder3d();
        for (entity, main_entity) in &material_meshes {
            let Some(mesh_instance) = render_mesh_instances.render_mesh_queue_data(*main_entity)
            else {
                continue;
            };
            let Some(mesh) = meshes.get(mesh_instance.mesh_asset_id) else {
                continue;
            };
            let key =
                view_key | MeshPipelineKey::from_primitive_topology(mesh.primitive_topology());
            let pipeline = pipelines
                .specialize(&pipeline_cache, &custom_pipeline, key, &mesh.layout)
                .unwrap();
            transparent_phase.add(Transparent3d {
                entity: (entity, *main_entity),
                pipeline,
                draw_function: draw_custom,
                distance: rangefinder.distance_translation(&mesh_instance.translation),
                batch_range: 0..1,
                extra_index: PhaseItemExtraIndex::None,
                indexed: true,
            });
        }
    }
}

examples/3d/manual_material.rs (line 151)

    fn prepare_asset(
        source_asset: Self::SourceAsset,
        asset_id: AssetId<Self::SourceAsset>,
        (
            opaque_draw_functions,
            material_layout,
            asset_server,
            bind_group_allocators,
            render_material_bindings,
            gpu_images,
            image_material_sampler,
        ): &mut SystemParamItem<Self::Param>,
    ) -> std::result::Result<Self::ErasedAsset, PrepareAssetError<Self::SourceAsset>> {
        let material_layout = material_layout.0.clone();
        let draw_function_id = opaque_draw_functions.read().id::<DrawMaterial>();
        let bind_group_allocator = bind_group_allocators
            .get_mut(&TypeId::of::<ImageMaterial>())
            .unwrap();
        let Some(image) = gpu_images.get(&source_asset.image) else {
            return Err(PrepareAssetError::RetryNextUpdate(source_asset));
        };
        let unprepared = UnpreparedBindGroup {
            bindings: BindingResources(vec![
                (
                    0,
                    OwnedBindingResource::TextureView(
                        TextureViewDimension::D2,
                        image.texture_view.clone(),
                    ),
                ),
                (
                    1,
                    OwnedBindingResource::Sampler(
                        SamplerBindingType::NonFiltering,
                        image_material_sampler.0.clone(),
                    ),
                ),
            ]),
        };
        let binding = match render_material_bindings.entry(asset_id.into()) {
            Entry::Occupied(mut occupied_entry) => {
                bind_group_allocator.free(*occupied_entry.get());
                let new_binding =
                    bind_group_allocator.allocate_unprepared(unprepared, &material_layout);
                *occupied_entry.get_mut() = new_binding;
                new_binding
            }
            Entry::Vacant(vacant_entry) => *vacant_entry
                .insert(bind_group_allocator.allocate_unprepared(unprepared, &material_layout)),
        };

        let mut properties = MaterialProperties {
            material_layout: Some(material_layout),
            ..Default::default()
        };
        properties.add_draw_function(MaterialDrawFunction, draw_function_id);
        properties.add_shader(MaterialFragmentShader, asset_server.load(SHADER_ASSET_PATH));

        Ok(PreparedMaterial {
            binding,
            properties: Arc::new(properties),
        })
    }
}

/// set up a simple 3D scene
fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ImageMaterial>>,
    asset_server: Res<AssetServer>,
) {
    // cube
    commands.spawn((
        Mesh3d(meshes.add(Cuboid::new(2.0, 2.0, 2.0))),
        ImageMaterial3d(materials.add(ImageMaterial {
            image: asset_server.load("branding/icon.png"),
        })),
        Transform::from_xyz(0.0, 0.5, 0.0),
    ));
    // light
    commands.spawn((
        PointLight {
            shadows_enabled: true,
            ..default()
        },
        Transform::from_xyz(4.0, 8.0, 4.0),
    ));
    // camera
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));
}

fn extract_image_materials(
    mut material_instances: ResMut<RenderMaterialInstances>,
    changed_meshes_query: Extract<
        Query<
            (Entity, &ViewVisibility, &ImageMaterial3d),
            Or<(Changed<ViewVisibility>, Changed<ImageMaterial3d>)>,
        >,
    >,
) {
    let last_change_tick = material_instances.current_change_tick;

    for (entity, view_visibility, material) in &changed_meshes_query {
        if view_visibility.get() {
            material_instances.instances.insert(
                entity.into(),
                RenderMaterialInstance {
                    asset_id: material.0.id().untyped(),
                    last_change_tick,
                },
            );
        } else {
            material_instances
                .instances
                .remove(&MainEntity::from(entity));
        }
    }
}

fn check_entities_needing_specialization(
    needs_specialization: Query<
        Entity,
        (
            Or<(
                Changed<Mesh3d>,
                AssetChanged<Mesh3d>,
                Changed<ImageMaterial3d>,
                AssetChanged<ImageMaterial3d>,
            )>,
            With<ImageMaterial3d>,
        ),
    >,
    mut par_local: Local<Parallel<Vec<Entity>>>,
    mut entities_needing_specialization: ResMut<EntitiesNeedingSpecialization<ImageMaterial>>,
) {
    entities_needing_specialization.clear();

    needs_specialization
        .par_iter()
        .for_each(|entity| par_local.borrow_local_mut().push(entity));

    par_local.drain_into(&mut entities_needing_specialization);
}

fn extract_image_materials_needing_specialization(
    entities_needing_specialization: Extract<Res<EntitiesNeedingSpecialization<ImageMaterial>>>,
    mut entity_specialization_ticks: ResMut<EntitySpecializationTicks>,
    mut removed_mesh_material_components: Extract<RemovedComponents<ImageMaterial3d>>,
    mut specialized_material_pipeline_cache: ResMut<SpecializedMaterialPipelineCache>,
    views: Query<&ExtractedView>,
    ticks: SystemChangeTick,
) {
    // Clean up any despawned entities, we do this first in case the removed material was re-added
    // the same frame, thus will appear both in the removed components list and have been added to
    // the `EntitiesNeedingSpecialization` collection by triggering the `Changed` filter
    for entity in removed_mesh_material_components.read() {
        entity_specialization_ticks.remove(&MainEntity::from(entity));
        for view in views {
            if let Some(cache) =
                specialized_material_pipeline_cache.get_mut(&view.retained_view_entity)
            {
                cache.remove(&MainEntity::from(entity));
            }
        }
    }

    for entity in entities_needing_specialization.iter() {
        // Update the entity's specialization tick with this run's tick
        entity_specialization_ticks.insert((*entity).into(), ticks.this_run());
    }
}

examples/2d/mesh2d_manual.rs (line 392)

pub fn queue_colored_mesh2d(
    transparent_draw_functions: Res<DrawFunctions<Transparent2d>>,
    colored_mesh2d_pipeline: Res<ColoredMesh2dPipeline>,
    mut pipelines: ResMut<SpecializedRenderPipelines<ColoredMesh2dPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    render_meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderColoredMesh2dInstances>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent2d>>,
    views: Query<(&RenderVisibleEntities, &ExtractedView, &Msaa)>,
) {
    if render_mesh_instances.is_empty() {
        return;
    }
    // Iterate each view (a camera is a view)
    for (visible_entities, view, msaa) in &views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&view.retained_view_entity)
        else {
            continue;
        };

        let draw_colored_mesh2d = transparent_draw_functions.read().id::<DrawColoredMesh2d>();

        let mesh_key = Mesh2dPipelineKey::from_msaa_samples(msaa.samples())
            | Mesh2dPipelineKey::from_hdr(view.hdr);

        // Queue all entities visible to that view
        for (render_entity, visible_entity) in visible_entities.iter::<Mesh2d>() {
            if let Some(mesh_instance) = render_mesh_instances.get(visible_entity) {
                let mesh2d_handle = mesh_instance.mesh_asset_id;
                let mesh2d_transforms = &mesh_instance.transforms;
                // Get our specialized pipeline
                let mut mesh2d_key = mesh_key;
                let Some(mesh) = render_meshes.get(mesh2d_handle) else {
                    continue;
                };
                mesh2d_key |= Mesh2dPipelineKey::from_primitive_topology(mesh.primitive_topology());

                let pipeline_id =
                    pipelines.specialize(&pipeline_cache, &colored_mesh2d_pipeline, mesh2d_key);

                let mesh_z = mesh2d_transforms.world_from_local.translation.z;
                transparent_phase.add(Transparent2d {
                    entity: (*render_entity, *visible_entity),
                    draw_function: draw_colored_mesh2d,
                    pipeline: pipeline_id,
                    // The 2d render items are sorted according to their z value before rendering,
                    // in order to get correct transparency
                    sort_key: FloatOrd(mesh_z),
                    // This material is not batched
                    batch_range: 0..1,
                    extra_index: PhaseItemExtraIndex::None,
                    extracted_index: usize::MAX,
                    indexed: mesh.indexed(),
                });
            }
        }
    }
}

examples/shader_advanced/custom_phase_item.rs (line 231)

fn queue_custom_phase_item(
    pipeline_cache: Res<PipelineCache>,
    mut pipeline: ResMut<CustomPhasePipeline>,
    mut opaque_render_phases: ResMut<ViewBinnedRenderPhases<Opaque3d>>,
    opaque_draw_functions: Res<DrawFunctions<Opaque3d>>,
    views: Query<(&ExtractedView, &RenderVisibleEntities, &Msaa)>,
    mut next_tick: Local<Tick>,
) {
    let draw_custom_phase_item = opaque_draw_functions
        .read()
        .id::<DrawCustomPhaseItemCommands>();

    // Render phases are per-view, so we need to iterate over all views so that
    // the entity appears in them. (In this example, we have only one view, but
    // it's good practice to loop over all views anyway.)
    for (view, view_visible_entities, msaa) in views.iter() {
        let Some(opaque_phase) = opaque_render_phases.get_mut(&view.retained_view_entity) else {
            continue;
        };

        // Find all the custom rendered entities that are visible from this
        // view.
        for &entity in view_visible_entities.get::<CustomRenderedEntity>().iter() {
            // Ordinarily, the [`SpecializedRenderPipeline::Key`] would contain
            // some per-view settings, such as whether the view is HDR, but for
            // simplicity's sake we simply hard-code the view's characteristics,
            // with the exception of number of MSAA samples.
            let Ok(pipeline_id) = pipeline
                .variants
                .specialize(&pipeline_cache, CustomPhaseKey(*msaa))
            else {
                continue;
            };

            // Bump the change tick in order to force Bevy to rebuild the bin.
            let this_tick = next_tick.get() + 1;
            next_tick.set(this_tick);

            // Add the custom render item. We use the
            // [`BinnedRenderPhaseType::NonMesh`] type to skip the special
            // handling that Bevy has for meshes (preprocessing, indirect
            // draws, etc.)
            //
            // The asset ID is arbitrary; we simply use [`AssetId::invalid`],
            // but you can use anything you like. Note that the asset ID need
            // not be the ID of a [`Mesh`].
            opaque_phase.add(
                Opaque3dBatchSetKey {
                    draw_function: draw_custom_phase_item,
                    pipeline: pipeline_id,
                    material_bind_group_index: None,
                    lightmap_slab: None,
                    vertex_slab: default(),
                    index_slab: None,
                },
                Opaque3dBinKey {
                    asset_id: AssetId::<Mesh>::invalid().untyped(),
                },
                entity,
                InputUniformIndex::default(),
                BinnedRenderPhaseType::NonMesh,
                *next_tick,
            );
        }
    }
}

examples/shader_advanced/custom_render_phase.rs (line 508)

fn queue_custom_meshes(
    custom_draw_functions: Res<DrawFunctions<Stencil3d>>,
    mut pipelines: ResMut<SpecializedMeshPipelines<StencilPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    custom_draw_pipeline: Res<StencilPipeline>,
    render_meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderMeshInstances>,
    mut custom_render_phases: ResMut<ViewSortedRenderPhases<Stencil3d>>,
    mut views: Query<(&ExtractedView, &RenderVisibleEntities, &Msaa)>,
    has_marker: Query<(), With<DrawStencil>>,
) {
    for (view, visible_entities, msaa) in &mut views {
        let Some(custom_phase) = custom_render_phases.get_mut(&view.retained_view_entity) else {
            continue;
        };
        let draw_custom = custom_draw_functions.read().id::<DrawMesh3dStencil>();

        // Create the key based on the view.
        // In this case we only care about MSAA and HDR
        let view_key = MeshPipelineKey::from_msaa_samples(msaa.samples())
            | MeshPipelineKey::from_hdr(view.hdr);

        let rangefinder = view.rangefinder3d();
        // Since our phase can work on any 3d mesh we can reuse the default mesh 3d filter
        for (render_entity, visible_entity) in visible_entities.iter::<Mesh3d>() {
            // We only want meshes with the marker component to be queued to our phase.
            if has_marker.get(*render_entity).is_err() {
                continue;
            }
            let Some(mesh_instance) = render_mesh_instances.render_mesh_queue_data(*visible_entity)
            else {
                continue;
            };
            let Some(mesh) = render_meshes.get(mesh_instance.mesh_asset_id) else {
                continue;
            };

            // Specialize the key for the current mesh entity
            // For this example we only specialize based on the mesh topology
            // but you could have more complex keys and that's where you'd need to create those keys
            let mut mesh_key = view_key;
            mesh_key |= MeshPipelineKey::from_primitive_topology(mesh.primitive_topology());

            let pipeline_id = pipelines.specialize(
                &pipeline_cache,
                &custom_draw_pipeline,
                mesh_key,
                &mesh.layout,
            );
            let pipeline_id = match pipeline_id {
                Ok(id) => id,
                Err(err) => {
                    error!("{}", err);
                    continue;
                }
            };
            let distance = rangefinder.distance_translation(&mesh_instance.translation);
            // At this point we have all the data we need to create a phase item and add it to our
            // phase
            custom_phase.add(Stencil3d {
                // Sort the data based on the distance to the view
                sort_key: FloatOrd(distance),
                entity: (*render_entity, *visible_entity),
                pipeline: pipeline_id,
                draw_function: draw_custom,
                // Sorted phase items aren't batched
                batch_range: 0..1,
                extra_index: PhaseItemExtraIndex::None,
                indexed: mesh.indexed(),
            });
        }
    }
}

Additional examples can be found in:

• examples/shader_advanced/specialized_mesh_pipeline.rs

pub fn get_many_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once.

Refer to get_many_mut for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

let result = map.get_many_mut(["foo", "bar"]);

assert_eq!(result, [Some(&mut 0), Some(&mut 1)]);

pub fn get_many_key_value_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<(&K, &mut V)>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once, with immutable references to the corresponding keys.

Refer to get_many_key_value_mut for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);
map.insert("bar", 1);
map.insert("baz", 2);

let result = map.get_many_key_value_mut(["foo", "bar"]);

assert_eq!(result, [Some((&"foo", &mut 0)), Some((&"bar", &mut 1))]);

pub fn insert(&mut self, k: K, v: V) -> Option<V>

Inserts a key-value pair into the map.

Refer to insert for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.get("foo"), Some(&0));

Examples found in repository

examples/ecs/immutable_components.rs (line 85)

fn on_insert_name(mut world: DeferredWorld<'_>, HookContext { entity, .. }: HookContext) {
    let Some(&name) = world.entity(entity).get::<Name>() else {
        unreachable!("Insert hook guarantees `Name` is available on entity")
    };
    let Some(mut index) = world.get_resource_mut::<NameIndex>() else {
        return;
    };

    index.name_to_entity.insert(name, entity);
}

tests/ecs/ambiguity_detection.rs (line 81)

fn count_ambiguities(sub_app: &SubApp) -> AmbiguitiesCount {
    let schedules = sub_app.world().resource::<Schedules>();
    let mut ambiguities = <HashMap<_, _>>::default();
    for (_, schedule) in schedules.iter() {
        let ambiguities_in_schedule = schedule.graph().conflicting_systems().len();
        ambiguities.insert(schedule.label(), ambiguities_in_schedule);
    }
    AmbiguitiesCount(ambiguities)
}

examples/3d/tonemapping.rs (lines 591-594)

    fn default() -> Self {
        let mut settings = <HashMap<_, _>>::default();

        for method in [
            Tonemapping::None,
            Tonemapping::Reinhard,
            Tonemapping::ReinhardLuminance,
            Tonemapping::AcesFitted,
            Tonemapping::AgX,
            Tonemapping::SomewhatBoringDisplayTransform,
            Tonemapping::TonyMcMapface,
            Tonemapping::BlenderFilmic,
        ] {
            settings.insert(
                method,
                PerMethodSettings::basic_scene_recommendation(method),
            );
        }

        Self { settings }
    }

examples/3d/manual_material.rs (lines 94-97)

fn init_image_material_resources(
    mut commands: Commands,
    render_device: Res<RenderDevice>,
    mut bind_group_allocators: ResMut<MaterialBindGroupAllocators>,
) {
    let bind_group_layout = render_device.create_bind_group_layout(
        "image_material_layout",
        &BindGroupLayoutEntries::sequential(
            ShaderStages::FRAGMENT,
            (
                texture_2d(TextureSampleType::Float { filterable: false }),
                sampler(SamplerBindingType::NonFiltering),
            ),
        ),
    );
    let sampler = render_device.create_sampler(&SamplerDescriptor::default());
    commands.insert_resource(ImageMaterialBindGroupLayout(bind_group_layout.clone()));
    commands.insert_resource(ImageMaterialBindGroupSampler(sampler));

    bind_group_allocators.insert(
        TypeId::of::<ImageMaterial>(),
        MaterialBindGroupAllocator::new(&render_device, None, None, bind_group_layout, None),
    );
}

#[derive(Resource)]
struct ImageMaterialBindGroupLayout(BindGroupLayout);

#[derive(Resource)]
struct ImageMaterialBindGroupSampler(Sampler);

#[derive(Component)]
struct ImageMaterial3d(Handle<ImageMaterial>);

impl AsAssetId for ImageMaterial3d {
    type Asset = ImageMaterial;

    fn as_asset_id(&self) -> AssetId<Self::Asset> {
        self.0.id()
    }
}

#[derive(Asset, TypePath, AsBindGroup, Debug, Clone)]
struct ImageMaterial {
    image: Handle<Image>,
}

impl ErasedRenderAsset for ImageMaterial {
    type SourceAsset = ImageMaterial;
    type ErasedAsset = PreparedMaterial;
    type Param = (
        SRes<DrawFunctions<Opaque3d>>,
        SRes<ImageMaterialBindGroupLayout>,
        SRes<AssetServer>,
        SResMut<MaterialBindGroupAllocators>,
        SResMut<RenderMaterialBindings>,
        SRes<RenderAssets<GpuImage>>,
        SRes<ImageMaterialBindGroupSampler>,
    );

    fn prepare_asset(
        source_asset: Self::SourceAsset,
        asset_id: AssetId<Self::SourceAsset>,
        (
            opaque_draw_functions,
            material_layout,
            asset_server,
            bind_group_allocators,
            render_material_bindings,
            gpu_images,
            image_material_sampler,
        ): &mut SystemParamItem<Self::Param>,
    ) -> std::result::Result<Self::ErasedAsset, PrepareAssetError<Self::SourceAsset>> {
        let material_layout = material_layout.0.clone();
        let draw_function_id = opaque_draw_functions.read().id::<DrawMaterial>();
        let bind_group_allocator = bind_group_allocators
            .get_mut(&TypeId::of::<ImageMaterial>())
            .unwrap();
        let Some(image) = gpu_images.get(&source_asset.image) else {
            return Err(PrepareAssetError::RetryNextUpdate(source_asset));
        };
        let unprepared = UnpreparedBindGroup {
            bindings: BindingResources(vec![
                (
                    0,
                    OwnedBindingResource::TextureView(
                        TextureViewDimension::D2,
                        image.texture_view.clone(),
                    ),
                ),
                (
                    1,
                    OwnedBindingResource::Sampler(
                        SamplerBindingType::NonFiltering,
                        image_material_sampler.0.clone(),
                    ),
                ),
            ]),
        };
        let binding = match render_material_bindings.entry(asset_id.into()) {
            Entry::Occupied(mut occupied_entry) => {
                bind_group_allocator.free(*occupied_entry.get());
                let new_binding =
                    bind_group_allocator.allocate_unprepared(unprepared, &material_layout);
                *occupied_entry.get_mut() = new_binding;
                new_binding
            }
            Entry::Vacant(vacant_entry) => *vacant_entry
                .insert(bind_group_allocator.allocate_unprepared(unprepared, &material_layout)),
        };

        let mut properties = MaterialProperties {
            material_layout: Some(material_layout),
            ..Default::default()
        };
        properties.add_draw_function(MaterialDrawFunction, draw_function_id);
        properties.add_shader(MaterialFragmentShader, asset_server.load(SHADER_ASSET_PATH));

        Ok(PreparedMaterial {
            binding,
            properties: Arc::new(properties),
        })
    }
}

/// set up a simple 3D scene
fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ImageMaterial>>,
    asset_server: Res<AssetServer>,
) {
    // cube
    commands.spawn((
        Mesh3d(meshes.add(Cuboid::new(2.0, 2.0, 2.0))),
        ImageMaterial3d(materials.add(ImageMaterial {
            image: asset_server.load("branding/icon.png"),
        })),
        Transform::from_xyz(0.0, 0.5, 0.0),
    ));
    // light
    commands.spawn((
        PointLight {
            shadows_enabled: true,
            ..default()
        },
        Transform::from_xyz(4.0, 8.0, 4.0),
    ));
    // camera
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(-2.5, 4.5, 9.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));
}

fn extract_image_materials(
    mut material_instances: ResMut<RenderMaterialInstances>,
    changed_meshes_query: Extract<
        Query<
            (Entity, &ViewVisibility, &ImageMaterial3d),
            Or<(Changed<ViewVisibility>, Changed<ImageMaterial3d>)>,
        >,
    >,
) {
    let last_change_tick = material_instances.current_change_tick;

    for (entity, view_visibility, material) in &changed_meshes_query {
        if view_visibility.get() {
            material_instances.instances.insert(
                entity.into(),
                RenderMaterialInstance {
                    asset_id: material.0.id().untyped(),
                    last_change_tick,
                },
            );
        } else {
            material_instances
                .instances
                .remove(&MainEntity::from(entity));
        }
    }
}

fn check_entities_needing_specialization(
    needs_specialization: Query<
        Entity,
        (
            Or<(
                Changed<Mesh3d>,
                AssetChanged<Mesh3d>,
                Changed<ImageMaterial3d>,
                AssetChanged<ImageMaterial3d>,
            )>,
            With<ImageMaterial3d>,
        ),
    >,
    mut par_local: Local<Parallel<Vec<Entity>>>,
    mut entities_needing_specialization: ResMut<EntitiesNeedingSpecialization<ImageMaterial>>,
) {
    entities_needing_specialization.clear();

    needs_specialization
        .par_iter()
        .for_each(|entity| par_local.borrow_local_mut().push(entity));

    par_local.drain_into(&mut entities_needing_specialization);
}

fn extract_image_materials_needing_specialization(
    entities_needing_specialization: Extract<Res<EntitiesNeedingSpecialization<ImageMaterial>>>,
    mut entity_specialization_ticks: ResMut<EntitySpecializationTicks>,
    mut removed_mesh_material_components: Extract<RemovedComponents<ImageMaterial3d>>,
    mut specialized_material_pipeline_cache: ResMut<SpecializedMaterialPipelineCache>,
    views: Query<&ExtractedView>,
    ticks: SystemChangeTick,
) {
    // Clean up any despawned entities, we do this first in case the removed material was re-added
    // the same frame, thus will appear both in the removed components list and have been added to
    // the `EntitiesNeedingSpecialization` collection by triggering the `Changed` filter
    for entity in removed_mesh_material_components.read() {
        entity_specialization_ticks.remove(&MainEntity::from(entity));
        for view in views {
            if let Some(cache) =
                specialized_material_pipeline_cache.get_mut(&view.retained_view_entity)
            {
                cache.remove(&MainEntity::from(entity));
            }
        }
    }

    for entity in entities_needing_specialization.iter() {
        // Update the entity's specialization tick with this run's tick
        entity_specialization_ticks.insert((*entity).into(), ticks.this_run());
    }
}

examples/2d/mesh2d_manual.rs (lines 361-370)

pub fn extract_colored_mesh2d(
    mut commands: Commands,
    mut previous_len: Local<usize>,
    // When extracting, you must use `Extract` to mark the `SystemParam`s
    // which should be taken from the main world.
    query: Extract<
        Query<
            (
                Entity,
                RenderEntity,
                &ViewVisibility,
                &GlobalTransform,
                &Mesh2d,
            ),
            With<ColoredMesh2d>,
        >,
    >,
    mut render_mesh_instances: ResMut<RenderColoredMesh2dInstances>,
) {
    let mut values = Vec::with_capacity(*previous_len);
    for (entity, render_entity, view_visibility, transform, handle) in &query {
        if !view_visibility.get() {
            continue;
        }

        let transforms = Mesh2dTransforms {
            world_from_local: (&transform.affine()).into(),
            flags: MeshFlags::empty().bits(),
        };

        values.push((render_entity, ColoredMesh2d));
        render_mesh_instances.insert(
            entity.into(),
            RenderMesh2dInstance {
                mesh_asset_id: handle.0.id(),
                transforms,
                material_bind_group_id: Material2dBindGroupId::default(),
                automatic_batching: false,
                tag: 0,
            },
        );
    }
    *previous_len = values.len();
    commands.try_insert_batch(values);
}

examples/reflection/reflection_types.rs (line 69)

fn setup() {
    let mut z = <HashMap<_, _>>::default();
    z.insert("Hello".to_string(), 1.0);
    let value: Box<dyn Reflect> = Box::new(A {
        x: 1,
        y: vec![1, 2],
        z,
    });

    // There are a number of different "reflect traits", which each expose different operations on
    // the underlying type
    match value.reflect_ref() {
        // `Struct` is a trait automatically implemented for structs that derive Reflect. This trait
        // allows you to interact with fields via their string names or indices
        ReflectRef::Struct(value) => {
            info!(
                "This is a 'struct' type with an 'x' value of {}",
                value.get_field::<usize>("x").unwrap()
            );
        }
        // `TupleStruct` is a trait automatically implemented for tuple structs that derive Reflect.
        // This trait allows you to interact with fields via their indices
        ReflectRef::TupleStruct(_) => {}
        // `Tuple` is a special trait that can be manually implemented (instead of deriving
        // Reflect). This exposes "tuple" operations on your type, allowing you to interact
        // with fields via their indices. Tuple is automatically implemented for tuples of
        // arity 12 or less.
        ReflectRef::Tuple(_) => {}
        // `Enum` is a trait automatically implemented for enums that derive Reflect. This trait allows you
        // to interact with the current variant and its fields (if it has any)
        ReflectRef::Enum(_) => {}
        // `List` is a special trait that can be manually implemented (instead of deriving Reflect).
        // This exposes "list" operations on your type, such as insertion. `List` is automatically
        // implemented for relevant core types like Vec<T>.
        ReflectRef::List(_) => {}
        // `Array` is a special trait that can be manually implemented (instead of deriving Reflect).
        // This exposes "array" operations on your type, such as indexing. `Array`
        // is automatically implemented for relevant core types like [T; N].
        ReflectRef::Array(_) => {}
        // `Map` is a special trait that can be manually implemented (instead of deriving Reflect).
        // This exposes "map" operations on your type, such as getting / inserting by key.
        // Map is automatically implemented for relevant core types like HashMap<K, V>
        ReflectRef::Map(_) => {}
        // `Set` is a special trait that can be manually implemented (instead of deriving Reflect).
        // This exposes "set" operations on your type, such as getting / inserting by value.
        // Set is automatically implemented for relevant core types like HashSet<T>
        ReflectRef::Set(_) => {}
        // `Function` is a special trait that can be manually implemented (instead of deriving Reflect).
        // This exposes "function" operations on your type, such as calling it with arguments.
        // This trait is automatically implemented for types like DynamicFunction.
        // This variant only exists if the `reflect_functions` feature is enabled.
        #[cfg(feature = "reflect_functions")]
        ReflectRef::Function(_) => {}
        // `Opaque` types do not implement any of the other traits above. They are simply a Reflect
        // implementation. Opaque is implemented for opaque types like String and Instant,
        // but also include primitive types like i32, usize, and f32 (despite not technically being opaque).
        ReflectRef::Opaque(_) => {}
        #[expect(
            clippy::allow_attributes,
            reason = "`unreachable_patterns` is not always linted"
        )]
        #[allow(
            unreachable_patterns,
            reason = "This example cannot always detect when `bevy_reflect/functions` is enabled."
        )]
        _ => {}
    }

    let mut dynamic_list = DynamicList::default();
    dynamic_list.push(3u32);
    dynamic_list.push(4u32);
    dynamic_list.push(5u32);

    let mut value: A = value.take::<A>().unwrap();
    value.y.apply(&dynamic_list);
    assert_eq!(value.y, vec![3u32, 4u32, 5u32]);

    // reference types defined above that are only used to demonstrate reflect
    // derive functionality:
    _ = || -> (A, B, C, D, E, F) { unreachable!() };
}

Additional examples can be found in:

• examples/ui/directional_navigation.rs

pub fn try_insert( &mut self, key: K, value: V, ) -> Result<&mut V, OccupiedError<'_, K, V, S>>

Tries to insert a key-value pair into the map, and returns a mutable reference to the value in the entry.

Refer to try_insert for further details.

Examples

let mut map = HashMap::new();

map.try_insert("foo", 0).unwrap();

assert!(map.try_insert("foo", 1).is_err());

pub fn remove<Q>(&mut self, k: &Q) -> Option<V>

where Q: Hash + Equivalent<K> + ?Sized,

Removes a key from the map, returning the value at the key if the key was previously in the map. Keeps the allocated memory for reuse.

Refer to remove for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.remove("foo"), Some(0));

assert!(map.is_empty());

Examples found in repository

examples/ecs/immutable_components.rs (line 100)

fn on_replace_name(mut world: DeferredWorld<'_>, HookContext { entity, .. }: HookContext) {
    let Some(&name) = world.entity(entity).get::<Name>() else {
        unreachable!("Replace hook guarantees `Name` is available on entity")
    };
    let Some(mut index) = world.get_resource_mut::<NameIndex>() else {
        return;
    };

    index.name_to_entity.remove(&name);
}

examples/3d/manual_material.rs (line 253)

fn extract_image_materials(
    mut material_instances: ResMut<RenderMaterialInstances>,
    changed_meshes_query: Extract<
        Query<
            (Entity, &ViewVisibility, &ImageMaterial3d),
            Or<(Changed<ViewVisibility>, Changed<ImageMaterial3d>)>,
        >,
    >,
) {
    let last_change_tick = material_instances.current_change_tick;

    for (entity, view_visibility, material) in &changed_meshes_query {
        if view_visibility.get() {
            material_instances.instances.insert(
                entity.into(),
                RenderMaterialInstance {
                    asset_id: material.0.id().untyped(),
                    last_change_tick,
                },
            );
        } else {
            material_instances
                .instances
                .remove(&MainEntity::from(entity));
        }
    }
}

fn check_entities_needing_specialization(
    needs_specialization: Query<
        Entity,
        (
            Or<(
                Changed<Mesh3d>,
                AssetChanged<Mesh3d>,
                Changed<ImageMaterial3d>,
                AssetChanged<ImageMaterial3d>,
            )>,
            With<ImageMaterial3d>,
        ),
    >,
    mut par_local: Local<Parallel<Vec<Entity>>>,
    mut entities_needing_specialization: ResMut<EntitiesNeedingSpecialization<ImageMaterial>>,
) {
    entities_needing_specialization.clear();

    needs_specialization
        .par_iter()
        .for_each(|entity| par_local.borrow_local_mut().push(entity));

    par_local.drain_into(&mut entities_needing_specialization);
}

fn extract_image_materials_needing_specialization(
    entities_needing_specialization: Extract<Res<EntitiesNeedingSpecialization<ImageMaterial>>>,
    mut entity_specialization_ticks: ResMut<EntitySpecializationTicks>,
    mut removed_mesh_material_components: Extract<RemovedComponents<ImageMaterial3d>>,
    mut specialized_material_pipeline_cache: ResMut<SpecializedMaterialPipelineCache>,
    views: Query<&ExtractedView>,
    ticks: SystemChangeTick,
) {
    // Clean up any despawned entities, we do this first in case the removed material was re-added
    // the same frame, thus will appear both in the removed components list and have been added to
    // the `EntitiesNeedingSpecialization` collection by triggering the `Changed` filter
    for entity in removed_mesh_material_components.read() {
        entity_specialization_ticks.remove(&MainEntity::from(entity));
        for view in views {
            if let Some(cache) =
                specialized_material_pipeline_cache.get_mut(&view.retained_view_entity)
            {
                cache.remove(&MainEntity::from(entity));
            }
        }
    }

    for entity in entities_needing_specialization.iter() {
        // Update the entity's specialization tick with this run's tick
        entity_specialization_ticks.insert((*entity).into(), ticks.this_run());
    }
}

pub fn remove_entry<Q>(&mut self, k: &Q) -> Option<(K, V)>

where Q: Hash + Equivalent<K> + ?Sized,

Removes a key from the map, returning the stored key and value if the key was previously in the map. Keeps the allocated memory for reuse.

Refer to remove_entry for further details.

Examples

let mut map = HashMap::new();

map.insert("foo", 0);

assert_eq!(map.remove_entry("foo"), Some(("foo", 0)));

assert!(map.is_empty());

pub fn allocation_size(&self) -> usize

Returns the total amount of memory allocated internally by the hash set, in bytes.

Refer to allocation_size for further details.

Examples

let mut map = HashMap::new();

assert_eq!(map.allocation_size(), 0);

map.insert("foo", 0u32);

assert!(map.allocation_size() >= size_of::<&'static str>() + size_of::<u32>());

pub unsafe fn insert_unique_unchecked( &mut self, key: K, value: V, ) -> (&K, &mut V)

Insert a key-value pair into the map without checking if the key already exists in the map.

Refer to insert_unique_unchecked for further details.

Safety

This operation is safe if a key does not exist in the map.

However, if a key exists in the map already, the behavior is unspecified: this operation may panic, loop forever, or any following operation with the map may panic, loop forever or return arbitrary result.

That said, this operation (and following operations) are guaranteed to not violate memory safety.

However this operation is still unsafe because the resulting HashMap may be passed to unsafe code which does expect the map to behave correctly, and would cause unsoundness as a result.

pub unsafe fn get_many_unchecked_mut<Q, const N: usize>( &mut self, keys: [&Q; N], ) -> [Option<&mut V>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once, without validating that the values are unique.

Refer to get_many_unchecked_mut for further details.

Returns an array of length N with the results of each query. None will be used if the key is missing.

For a safe alternative see get_many_mut.

Safety

Calling this method with overlapping keys is undefined behavior even if the resulting references are not used.

pub unsafe fn get_many_key_value_unchecked_mut<Q, const N: usize>( &mut self, keys: [&Q; N], ) -> [Option<(&K, &mut V)>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once, with immutable references to the corresponding keys, without validating that the values are unique.

Refer to get_many_key_value_unchecked_mut for further details.

Returns an array of length N with the results of each query. None will be returned if any of the keys are missing.

For a safe alternative see get_many_key_value_mut.

Safety

Calling this method with overlapping keys is undefined behavior even if the resulting references are not used.

Methods from Deref<Target = HashMap<K, V, S>>

pub fn allocator(&self) -> &A

Returns a reference to the underlying allocator.

pub fn hasher(&self) -> &S

Returns a reference to the map’s BuildHasher.

Examples

use hashbrown::HashMap;
use hashbrown::DefaultHashBuilder;

let hasher = DefaultHashBuilder::default();
let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
let hasher: &DefaultHashBuilder = map.hasher();

pub fn capacity(&self) -> usize

Returns the number of elements the map can hold without reallocating.

This number is a lower bound; the HashMap<K, V> might be able to hold more, but is guaranteed to be able to hold at least this many.

Examples

use hashbrown::HashMap;
let map: HashMap<i32, i32> = HashMap::with_capacity(100);
assert_eq!(map.len(), 0);
assert!(map.capacity() >= 100);

pub fn keys(&self) -> Keys<'_, K, V>

An iterator visiting all keys in arbitrary order. The iterator element type is &'a K.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
assert_eq!(map.len(), 3);
let mut vec: Vec<&str> = Vec::new();

for key in map.keys() {
    println!("{}", key);
    vec.push(*key);
}

// The `Keys` iterator produces keys in arbitrary order, so the
// keys must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, ["a", "b", "c"]);

assert_eq!(map.len(), 3);

pub fn values(&self) -> Values<'_, K, V>

An iterator visiting all values in arbitrary order. The iterator element type is &'a V.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
assert_eq!(map.len(), 3);
let mut vec: Vec<i32> = Vec::new();

for val in map.values() {
    println!("{}", val);
    vec.push(*val);
}

// The `Values` iterator produces values in arbitrary order, so the
// values must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [1, 2, 3]);

assert_eq!(map.len(), 3);

pub fn values_mut(&mut self) -> ValuesMut<'_, K, V>

An iterator visiting all values mutably in arbitrary order. The iterator element type is &'a mut V.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();

map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

for val in map.values_mut() {
    *val = *val + 10;
}

assert_eq!(map.len(), 3);
let mut vec: Vec<i32> = Vec::new();

for val in map.values() {
    println!("{}", val);
    vec.push(*val);
}

// The `Values` iterator produces values in arbitrary order, so the
// values must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [11, 12, 13]);

assert_eq!(map.len(), 3);

pub fn iter(&self) -> Iter<'_, K, V>

An iterator visiting all key-value pairs in arbitrary order. The iterator element type is (&'a K, &'a V).

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);
assert_eq!(map.len(), 3);
let mut vec: Vec<(&str, i32)> = Vec::new();

for (key, val) in map.iter() {
    println!("key: {} val: {}", key, val);
    vec.push((*key, *val));
}

// The `Iter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [("a", 1), ("b", 2), ("c", 3)]);

assert_eq!(map.len(), 3);

pub fn iter_mut(&mut self) -> IterMut<'_, K, V>

An iterator visiting all key-value pairs in arbitrary order, with mutable references to the values. The iterator element type is (&'a K, &'a mut V).

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

// Update all values
for (_, val) in map.iter_mut() {
    *val *= 2;
}

assert_eq!(map.len(), 3);
let mut vec: Vec<(&str, i32)> = Vec::new();

for (key, val) in &map {
    println!("key: {} val: {}", key, val);
    vec.push((*key, *val));
}

// The `Iter` iterator produces items in arbitrary order, so the
// items must be sorted to test them against a sorted array.
vec.sort_unstable();
assert_eq!(vec, [("a", 2), ("b", 4), ("c", 6)]);

assert_eq!(map.len(), 3);

pub fn len(&self) -> usize

Returns the number of elements in the map.

Examples

use hashbrown::HashMap;

let mut a = HashMap::new();
assert_eq!(a.len(), 0);
a.insert(1, "a");
assert_eq!(a.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Examples

use hashbrown::HashMap;

let mut a = HashMap::new();
assert!(a.is_empty());
a.insert(1, "a");
assert!(!a.is_empty());

pub fn drain(&mut self) -> Drain<'_, K, V, A>

Clears the map, returning all key-value pairs as an iterator. Keeps the allocated memory for reuse.

If the returned iterator is dropped before being fully consumed, it drops the remaining key-value pairs. The returned iterator keeps a mutable borrow on the vector to optimize its implementation.

Examples

use hashbrown::HashMap;

let mut a = HashMap::new();
a.insert(1, "a");
a.insert(2, "b");
let capacity_before_drain = a.capacity();

for (k, v) in a.drain().take(1) {
    assert!(k == 1 || k == 2);
    assert!(v == "a" || v == "b");
}

// As we can see, the map is empty and contains no element.
assert!(a.is_empty() && a.len() == 0);
// But map capacity is equal to old one.
assert_eq!(a.capacity(), capacity_before_drain);

let mut a = HashMap::new();
a.insert(1, "a");
a.insert(2, "b");

{   // Iterator is dropped without being consumed.
    let d = a.drain();
}

// But the map is empty even if we do not use Drain iterator.
assert!(a.is_empty());

pub fn retain<F>(&mut self, f: F)

where F: FnMut(&K, &mut V) -> bool,

Retains only the elements specified by the predicate. Keeps the allocated memory for reuse.

In other words, remove all pairs (k, v) such that f(&k, &mut v) returns false. The elements are visited in unsorted (and unspecified) order.

Examples

use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x|(x, x*10)).collect();
assert_eq!(map.len(), 8);

map.retain(|&k, _| k % 2 == 0);

// We can see, that the number of elements inside map is changed.
assert_eq!(map.len(), 4);

let mut vec: Vec<(i32, i32)> = map.iter().map(|(&k, &v)| (k, v)).collect();
vec.sort_unstable();
assert_eq!(vec, [(0, 0), (2, 20), (4, 40), (6, 60)]);

pub fn extract_if<F>(&mut self, f: F) -> ExtractIf<'_, K, V, F, A>

where F: FnMut(&K, &mut V) -> bool,

Drains elements which are true under the given predicate, and returns an iterator over the removed items.

In other words, move all pairs (k, v) such that f(&k, &mut v) returns true out into another iterator.

Note that extract_if lets you mutate every value in the filter closure, regardless of whether you choose to keep or remove it.

If the returned ExtractIf is not exhausted, e.g. because it is dropped without iterating or the iteration short-circuits, then the remaining elements will be retained. Use retain() with a negated predicate if you do not need the returned iterator.

Keeps the allocated memory for reuse.

Examples

use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();

let drained: HashMap<i32, i32> = map.extract_if(|k, _v| k % 2 == 0).collect();

let mut evens = drained.keys().cloned().collect::<Vec<_>>();
let mut odds = map.keys().cloned().collect::<Vec<_>>();
evens.sort();
odds.sort();

assert_eq!(evens, vec![0, 2, 4, 6]);
assert_eq!(odds, vec![1, 3, 5, 7]);

let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x)).collect();

{   // Iterator is dropped without being consumed.
    let d = map.extract_if(|k, _v| k % 2 != 0);
}

// ExtractIf was not exhausted, therefore no elements were drained.
assert_eq!(map.len(), 8);

pub fn clear(&mut self)

Clears the map, removing all key-value pairs. Keeps the allocated memory for reuse.

Examples

use hashbrown::HashMap;

let mut a = HashMap::new();
a.insert(1, "a");
let capacity_before_clear = a.capacity();

a.clear();

// Map is empty.
assert!(a.is_empty());
// But map capacity is equal to old one.
assert_eq!(a.capacity(), capacity_before_clear);

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted in the HashMap. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new capacity exceeds isize::MAX bytes and abort the program in case of allocation error. Use try_reserve instead if you want to handle memory allocation failure.

Examples

use hashbrown::HashMap;
let mut map: HashMap<&str, i32> = HashMap::new();
// Map is empty and doesn't allocate memory
assert_eq!(map.capacity(), 0);

map.reserve(10);

// And now map can hold at least 10 elements
assert!(map.capacity() >= 10);

pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>

Tries to reserve capacity for at least additional more elements to be inserted in the given HashMap<K,V>. The collection may reserve more space to avoid frequent reallocations.

Errors

If the capacity overflows, or the allocator reports a failure, then an error is returned.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, isize> = HashMap::new();
// Map is empty and doesn't allocate memory
assert_eq!(map.capacity(), 0);

map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");

// And now map can hold at least 10 elements
assert!(map.capacity() >= 10);

If the capacity overflows, or the allocator reports a failure, then an error is returned:

use hashbrown::HashMap;
use hashbrown::TryReserveError;
let mut map: HashMap<i32, i32> = HashMap::new();

match map.try_reserve(usize::MAX) {
    Err(error) => match error {
        TryReserveError::CapacityOverflow => {}
        _ => panic!("TryReserveError::AllocError ?"),
    },
    _ => panic!(),
}

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of the map as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Examples

use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
map.insert(1, 2);
map.insert(3, 4);
assert!(map.capacity() >= 100);
map.shrink_to_fit();
assert!(map.capacity() >= 2);

pub fn shrink_to(&mut self, min_capacity: usize)

Shrinks the capacity of the map with a lower limit. It will drop down no lower than the supplied limit while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

This function does nothing if the current capacity is smaller than the supplied minimum capacity.

Examples

use hashbrown::HashMap;

let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
map.insert(1, 2);
map.insert(3, 4);
assert!(map.capacity() >= 100);
map.shrink_to(10);
assert!(map.capacity() >= 10);
map.shrink_to(0);
assert!(map.capacity() >= 2);
map.shrink_to(10);
assert!(map.capacity() >= 2);

pub fn entry(&mut self, key: K) -> Entry<'_, K, V, S, A>

Gets the given key’s corresponding entry in the map for in-place manipulation.

Examples

use hashbrown::HashMap;

let mut letters = HashMap::new();

for ch in "a short treatise on fungi".chars() {
    let counter = letters.entry(ch).or_insert(0);
    *counter += 1;
}

assert_eq!(letters[&'s'], 2);
assert_eq!(letters[&'t'], 3);
assert_eq!(letters[&'u'], 1);
assert_eq!(letters.get(&'y'), None);

pub fn entry_ref<'a, 'b, Q>( &'a mut self, key: &'b Q, ) -> EntryRef<'a, 'b, K, Q, V, S, A>

where Q: Hash + Equivalent<K> + ?Sized,

Gets the given key’s corresponding entry by reference in the map for in-place manipulation.

Examples

use hashbrown::HashMap;

let mut words: HashMap<String, usize> = HashMap::new();
let source = ["poneyland", "horseyland", "poneyland", "poneyland"];
for (i, &s) in source.iter().enumerate() {
    let counter = words.entry_ref(s).or_insert(0);
    *counter += 1;
}

assert_eq!(words["poneyland"], 3);
assert_eq!(words["horseyland"], 1);

pub fn get<Q>(&self, k: &Q) -> Option<&V>

where Q: Hash + Equivalent<K> + ?Sized,

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.get(&1), Some(&"a"));
assert_eq!(map.get(&2), None);

pub fn get_key_value<Q>(&self, k: &Q) -> Option<(&K, &V)>

where Q: Hash + Equivalent<K> + ?Sized,

Returns the key-value pair corresponding to the supplied key.

The supplied key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
assert_eq!(map.get_key_value(&2), None);

pub fn get_key_value_mut<Q>(&mut self, k: &Q) -> Option<(&K, &mut V)>

where Q: Hash + Equivalent<K> + ?Sized,

Returns the key-value pair corresponding to the supplied key, with a mutable reference to value.

The supplied key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
let (k, v) = map.get_key_value_mut(&1).unwrap();
assert_eq!(k, &1);
assert_eq!(v, &mut "a");
*v = "b";
assert_eq!(map.get_key_value_mut(&1), Some((&1, &mut "b")));
assert_eq!(map.get_key_value_mut(&2), None);

pub fn contains_key<Q>(&self, k: &Q) -> bool

where Q: Hash + Equivalent<K> + ?Sized,

Returns true if the map contains a value for the specified key.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.contains_key(&1), true);
assert_eq!(map.contains_key(&2), false);

pub fn get_mut<Q>(&mut self, k: &Q) -> Option<&mut V>

where Q: Hash + Equivalent<K> + ?Sized,

Returns a mutable reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
if let Some(x) = map.get_mut(&1) {
    *x = "b";
}
assert_eq!(map[&1], "b");

assert_eq!(map.get_mut(&2), None);

pub fn get_many_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once.

Returns an array of length N with the results of each query. For soundness, at most one mutable reference will be returned to any value. None will be used if the key is missing.

Panics

Panics if any keys are overlapping.

Examples

use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

// Get Athenæum and Bodleian Library
let [Some(a), Some(b)] = libraries.get_many_mut([
    "Athenæum",
    "Bodleian Library",
]) else { panic!() };

// Assert values of Athenæum and Library of Congress
let got = libraries.get_many_mut([
    "Athenæum",
    "Library of Congress",
]);
assert_eq!(
    got,
    [
        Some(&mut 1807),
        Some(&mut 1800),
    ],
);

// Missing keys result in None
let got = libraries.get_many_mut([
    "Athenæum",
    "New York Public Library",
]);
assert_eq!(
    got,
    [
        Some(&mut 1807),
        None
    ]
);

use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Athenæum".to_string(), 1807);

// Duplicate keys panic!
let got = libraries.get_many_mut([
    "Athenæum",
    "Athenæum",
]);

pub unsafe fn get_many_unchecked_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<&mut V>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once, without validating that the values are unique.

Returns an array of length N with the results of each query. None will be used if the key is missing.

For a safe alternative see get_many_mut.

Safety

Calling this method with overlapping keys is undefined behavior even if the resulting references are not used.

Examples

use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

// SAFETY: The keys do not overlap.
let [Some(a), Some(b)] = (unsafe { libraries.get_many_unchecked_mut([
    "Athenæum",
    "Bodleian Library",
]) }) else { panic!() };

// SAFETY: The keys do not overlap.
let got = unsafe { libraries.get_many_unchecked_mut([
    "Athenæum",
    "Library of Congress",
]) };
assert_eq!(
    got,
    [
        Some(&mut 1807),
        Some(&mut 1800),
    ],
);

// SAFETY: The keys do not overlap.
let got = unsafe { libraries.get_many_unchecked_mut([
    "Athenæum",
    "New York Public Library",
]) };
// Missing keys result in None
assert_eq!(got, [Some(&mut 1807), None]);

pub fn get_many_key_value_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<(&K, &mut V)>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once, with immutable references to the corresponding keys.

Returns an array of length N with the results of each query. For soundness, at most one mutable reference will be returned to any value. None will be used if the key is missing.

Panics

Panics if any keys are overlapping.

Examples

use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
]);
assert_eq!(
    got,
    [
        Some((&"Bodleian Library".to_string(), &mut 1602)),
        Some((&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut 1691)),
    ],
);
// Missing keys result in None
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Gewandhaus",
]);
assert_eq!(got, [Some((&"Bodleian Library".to_string(), &mut 1602)), None]);

use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);

// Duplicate keys result in panic!
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
    "Herzogin-Anna-Amalia-Bibliothek",
]);

pub unsafe fn get_many_key_value_unchecked_mut<Q, const N: usize>( &mut self, ks: [&Q; N], ) -> [Option<(&K, &mut V)>; N]

where Q: Hash + Equivalent<K> + ?Sized,

Attempts to get mutable references to N values in the map at once, with immutable references to the corresponding keys, without validating that the values are unique.

Returns an array of length N with the results of each query. None will be returned if any of the keys are missing.

For a safe alternative see get_many_key_value_mut.

Safety

Calling this method with overlapping keys is undefined behavior even if the resulting references are not used.

Examples

use hashbrown::HashMap;

let mut libraries = HashMap::new();
libraries.insert("Bodleian Library".to_string(), 1602);
libraries.insert("Athenæum".to_string(), 1807);
libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
libraries.insert("Library of Congress".to_string(), 1800);

let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
]);
assert_eq!(
    got,
    [
        Some((&"Bodleian Library".to_string(), &mut 1602)),
        Some((&"Herzogin-Anna-Amalia-Bibliothek".to_string(), &mut 1691)),
    ],
);
// Missing keys result in None
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Gewandhaus",
]);
assert_eq!(
    got,
    [
        Some((&"Bodleian Library".to_string(), &mut 1602)),
        None,
    ],
);

pub fn insert(&mut self, k: K, v: V) -> Option<V>

Inserts a key-value pair into the map.

If the map did not have this key present, None is returned.

If the map did have this key present, the value is updated, and the old value is returned. The key is not updated, though; this matters for types that can be == without being identical. See the std::collections module-level documentation for more.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
assert_eq!(map.insert(37, "a"), None);
assert_eq!(map.is_empty(), false);

map.insert(37, "b");
assert_eq!(map.insert(37, "c"), Some("b"));
assert_eq!(map[&37], "c");

pub unsafe fn insert_unique_unchecked(&mut self, k: K, v: V) -> (&K, &mut V)

Insert a key-value pair into the map without checking if the key already exists in the map.

This operation is faster than regular insert, because it does not perform lookup before insertion.

This operation is useful during initial population of the map. For example, when constructing a map from another map, we know that keys are unique.

Returns a reference to the key and value just inserted.

Safety

This operation is safe if a key does not exist in the map.

However, if a key exists in the map already, the behavior is unspecified: this operation may panic, loop forever, or any following operation with the map may panic, loop forever or return arbitrary result.

That said, this operation (and following operations) are guaranteed to not violate memory safety.

However this operation is still unsafe because the resulting HashMap may be passed to unsafe code which does expect the map to behave correctly, and would cause unsoundness as a result.

Examples

use hashbrown::HashMap;

let mut map1 = HashMap::new();
assert_eq!(map1.insert(1, "a"), None);
assert_eq!(map1.insert(2, "b"), None);
assert_eq!(map1.insert(3, "c"), None);
assert_eq!(map1.len(), 3);

let mut map2 = HashMap::new();

for (key, value) in map1.into_iter() {
    unsafe {
        map2.insert_unique_unchecked(key, value);
    }
}

let (key, value) = unsafe { map2.insert_unique_unchecked(4, "d") };
assert_eq!(key, &4);
assert_eq!(value, &mut "d");
*value = "e";

assert_eq!(map2[&1], "a");
assert_eq!(map2[&2], "b");
assert_eq!(map2[&3], "c");
assert_eq!(map2[&4], "e");
assert_eq!(map2.len(), 4);

pub fn try_insert( &mut self, key: K, value: V, ) -> Result<&mut V, OccupiedError<'_, K, V, S, A>>

Tries to insert a key-value pair into the map, and returns a mutable reference to the value in the entry.

Errors

If the map already had this key present, nothing is updated, and an error containing the occupied entry and the value is returned.

Examples

Basic usage:

use hashbrown::HashMap;
use hashbrown::hash_map::OccupiedError;

let mut map = HashMap::new();
assert_eq!(map.try_insert(37, "a").unwrap(), &"a");

match map.try_insert(37, "b") {
    Err(OccupiedError { entry, value }) => {
        assert_eq!(entry.key(), &37);
        assert_eq!(entry.get(), &"a");
        assert_eq!(value, "b");
    }
    _ => panic!()
}

pub fn remove<Q>(&mut self, k: &Q) -> Option<V>

where Q: Hash + Equivalent<K> + ?Sized,

Removes a key from the map, returning the value at the key if the key was previously in the map. Keeps the allocated memory for reuse.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
// The map is empty
assert!(map.is_empty() && map.capacity() == 0);

map.insert(1, "a");

assert_eq!(map.remove(&1), Some("a"));
assert_eq!(map.remove(&1), None);

// Now map holds none elements
assert!(map.is_empty());

pub fn remove_entry<Q>(&mut self, k: &Q) -> Option<(K, V)>

where Q: Hash + Equivalent<K> + ?Sized,

Removes a key from the map, returning the stored key and value if the key was previously in the map. Keeps the allocated memory for reuse.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use hashbrown::HashMap;

let mut map = HashMap::new();
// The map is empty
assert!(map.is_empty() && map.capacity() == 0);

map.insert(1, "a");

assert_eq!(map.remove_entry(&1), Some((1, "a")));
assert_eq!(map.remove(&1), None);

// Now map hold none elements
assert!(map.is_empty());

pub fn allocation_size(&self) -> usize

Returns the total amount of memory allocated internally by the hash set, in bytes.

The returned number is informational only. It is intended to be primarily used for memory profiling.

pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<'_, K, V, S, A>

Creates a raw entry builder for the HashMap.

Raw entries provide the lowest level of control for searching and manipulating a map. They must be manually initialized with a hash and then manually searched. After this, insertions into a vacant entry still require an owned key to be provided.

Raw entries are useful for such exotic situations as:

• Hash memoization
• Deferring the creation of an owned key until it is known to be required
• Using a search key that doesn’t work with the Borrow trait
• Using custom comparison logic without newtype wrappers

Because raw entries provide much more low-level control, it’s much easier to put the HashMap into an inconsistent state which, while memory-safe, will cause the map to produce seemingly random results. Higher-level and more foolproof APIs like entry should be preferred when possible.

In particular, the hash used to initialized the raw entry must still be consistent with the hash of the key that is ultimately stored in the entry. This is because implementations of HashMap may need to recompute hashes when resizing, at which point only the keys are available.

Raw entries give mutable access to the keys. This must not be used to modify how the key would compare or hash, as the map will not re-evaluate where the key should go, meaning the keys may become “lost” if their location does not reflect their state. For instance, if you change a key so that the map now contains keys which compare equal, search may start acting erratically, with two keys randomly masking each other. Implementations are free to assume this doesn’t happen (within the limits of memory-safety).

Examples

use core::hash::{BuildHasher, Hash};
use hashbrown::hash_map::{HashMap, RawEntryMut};

let mut map = HashMap::new();
map.extend([("a", 100), ("b", 200), ("c", 300)]);

fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
    use core::hash::Hasher;
    let mut state = hash_builder.build_hasher();
    key.hash(&mut state);
    state.finish()
}

// Existing key (insert and update)
match map.raw_entry_mut().from_key(&"a") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(mut view) => {
        assert_eq!(view.get(), &100);
        let v = view.get_mut();
        let new_v = (*v) * 10;
        *v = new_v;
        assert_eq!(view.insert(1111), 1000);
    }
}

assert_eq!(map[&"a"], 1111);
assert_eq!(map.len(), 3);

// Existing key (take)
let hash = compute_hash(map.hasher(), &"c");
match map.raw_entry_mut().from_key_hashed_nocheck(hash, &"c") {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(view) => {
        assert_eq!(view.remove_entry(), ("c", 300));
    }
}
assert_eq!(map.raw_entry().from_key(&"c"), None);
assert_eq!(map.len(), 2);

// Nonexistent key (insert and update)
let key = "d";
let hash = compute_hash(map.hasher(), &key);
match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
    RawEntryMut::Occupied(_) => unreachable!(),
    RawEntryMut::Vacant(view) => {
        let (k, value) = view.insert("d", 4000);
        assert_eq!((*k, *value), ("d", 4000));
        *value = 40000;
    }
}
assert_eq!(map[&"d"], 40000);
assert_eq!(map.len(), 3);

match map.raw_entry_mut().from_hash(hash, |q| *q == key) {
    RawEntryMut::Vacant(_) => unreachable!(),
    RawEntryMut::Occupied(view) => {
        assert_eq!(view.remove_entry(), ("d", 40000));
    }
}
assert_eq!(map.get(&"d"), None);
assert_eq!(map.len(), 2);

pub fn raw_entry(&self) -> RawEntryBuilder<'_, K, V, S, A>

Creates a raw immutable entry builder for the HashMap.

Raw entries provide the lowest level of control for searching and manipulating a map. They must be manually initialized with a hash and then manually searched.

This is useful for

• Hash memoization
• Using a search key that doesn’t work with the Borrow trait
• Using custom comparison logic without newtype wrappers

Unless you are in such a situation, higher-level and more foolproof APIs like get should be preferred.

Immutable raw entries have very limited use; you might instead want raw_entry_mut.

Examples

use core::hash::{BuildHasher, Hash};
use hashbrown::HashMap;

let mut map = HashMap::new();
map.extend([("a", 100), ("b", 200), ("c", 300)]);

fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 {
    use core::hash::Hasher;
    let mut state = hash_builder.build_hasher();
    key.hash(&mut state);
    state.finish()
}

for k in ["a", "b", "c", "d", "e", "f"] {
    let hash = compute_hash(map.hasher(), k);
    let v = map.get(&k).cloned();
    let kv = v.as_ref().map(|v| (&k, v));

    println!("Key: {} and value: {:?}", k, v);

    assert_eq!(map.raw_entry().from_key(&k), kv);
    assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
    assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
}

Trait Implementations

impl<K, V, S> Clone for HashMap<K, V, S>

where HashMap<K, V, S>: Clone,

fn clone(&self) -> HashMap<K, V, S>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &HashMap<K, V, S>)

Performs copy-assignment from source.

impl<K, V, S> Debug for HashMap<K, V, S>

where HashMap<K, V, S>: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<K, V, S> Default for HashMap<K, V, S>

where HashMap<K, V, S>: Default,

fn default() -> HashMap<K, V, S>

Returns the “default value” for a type.

impl<K, V, S> Deref for HashMap<K, V, S>

type Target = HashMap<K, V, S>

The resulting type after dereferencing.

fn deref(&self) -> &<HashMap<K, V, S> as Deref>::Target

Dereferences the value.

impl<K, V, S> DerefMut for HashMap<K, V, S>

fn deref_mut(&mut self) -> &mut <HashMap<K, V, S> as Deref>::Target

Mutably dereferences the value.

impl<'de, K, V, S> Deserialize<'de> for HashMap<K, V, S>

where HashMap<K, V, S>: Deserialize<'de>,

fn deserialize<D>( deserializer: D, ) -> Result<HashMap<K, V, S>, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<K, V, S, T> Extend<T> for HashMap<K, V, S>

where HashMap<K, V, S>: Extend<T>,

fn extend<U>(&mut self, iter: U)

where U: IntoIterator<Item = T>,

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<K, V, const N: usize> From<[(K, V); N]> for HashMap<K, V>

where K: Eq + Hash,

fn from(arr: [(K, V); N]) -> HashMap<K, V>

Converts to this type from the input type.

impl<K, V, S> From<HashMap<K, V, S>> for HashMap<K, V, S>

fn from(value: HashMap<K, V, S>) -> HashMap<K, V, S>

Converts to this type from the input type.

impl<K, V, S> From<HashMap<K, V, S>> for HashMap<K, V, S>

fn from(value: HashMap<K, V, S>) -> HashMap<K, V, S>

Converts to this type from the input type.

impl<T, S> From<HashMap<T, (), S>> for HashSet<T, S>

fn from(value: HashMap<T, (), S>) -> HashSet<T, S>

Converts to this type from the input type.

impl<K, V, S> FromArg for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

type This<'from_arg> = HashMap<K, V, S>

The type to convert into.

fn from_arg( arg: Arg<'_>, ) -> Result<<HashMap<K, V, S> as FromArg>::This<'_>, ArgError>

Creates an item from an argument.

impl<K, V, S, T> FromIterator<T> for HashMap<K, V, S>

where HashMap<K, V, S>: FromIterator<T>,

fn from_iter<U>(iter: U) -> HashMap<K, V, S>

where U: IntoIterator<Item = T>,

Creates a value from an iterator.

impl<K, V, S> FromReflect for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn from_reflect( reflect: &(dyn PartialReflect + 'static), ) -> Option<HashMap<K, V, S>>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl<K, V, S> GetOwnership for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn ownership() -> Ownership

Returns the ownership of Self.

impl<K, V, S> GetTypeRegistration for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl<K, V, S, T> Index<T> for HashMap<K, V, S>

where HashMap<K, V, S>: Index<T>,

type Output = <HashMap<K, V, S> as Index<T>>::Output

The returned type after indexing.

fn index(&self, index: T) -> &<HashMap<K, V, S> as Index<T>>::Output

Performs the indexing (container[index]) operation.

impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S>

where &'a HashMap<K, V, S>: IntoIterator,

type Item = <&'a HashMap<K, V, S> as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a HashMap<K, V, S> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a HashMap<K, V, S> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S>

where &'a mut HashMap<K, V, S>: IntoIterator,

type Item = <&'a mut HashMap<K, V, S> as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a mut HashMap<K, V, S> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a mut HashMap<K, V, S> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<K, V, S> IntoIterator for HashMap<K, V, S>

where HashMap<K, V, S>: IntoIterator,

type Item = <HashMap<K, V, S> as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <HashMap<K, V, S> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <HashMap<K, V, S> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<K, V, S> IntoReturn for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn into_return<'into_return>(self) -> Return<'into_return>

where HashMap<K, V, S>: 'into_return,

Converts Self into a Return value.

impl<K, V, S> Map for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn get( &self, key: &(dyn PartialReflect + 'static), ) -> Option<&(dyn PartialReflect + 'static)>

Returns a reference to the value associated with the given key.

fn get_mut( &mut self, key: &(dyn PartialReflect + 'static), ) -> Option<&mut (dyn PartialReflect + 'static)>

Returns a mutable reference to the value associated with the given key.

fn len(&self) -> usize

Returns the number of elements in the map.

fn iter( &self, ) -> Box<dyn Iterator<Item = (&(dyn PartialReflect + 'static), &(dyn PartialReflect + 'static))> + '_>

Returns an iterator over the key-value pairs of the map.

fn drain(&mut self) -> Vec<(Box<dyn PartialReflect>, Box<dyn PartialReflect>)>

Drain the key-value pairs of this map to get a vector of owned values.

fn retain( &mut self, f: &mut dyn FnMut(&(dyn PartialReflect + 'static), &mut (dyn PartialReflect + 'static)) -> bool, )

Retain only the elements specified by the predicate.

fn to_dynamic_map(&self) -> DynamicMap

Creates a new DynamicMap from this map.

fn insert_boxed( &mut self, key: Box<dyn PartialReflect>, value: Box<dyn PartialReflect>, ) -> Option<Box<dyn PartialReflect>>

Inserts a key-value pair into the map.

fn remove( &mut self, key: &(dyn PartialReflect + 'static), ) -> Option<Box<dyn PartialReflect>>

Removes an entry from the map.

fn is_empty(&self) -> bool

Returns true if the list contains no elements.

fn get_represented_map_info(&self) -> Option<&'static MapInfo>

Will return None if TypeInfo is not available.

impl<K, V, S> MapEntities for HashMap<K, V, S>

where K: MapEntities + Eq + Hash, V: MapEntities, S: BuildHasher + Default,

fn map_entities<E>(&mut self, entity_mapper: &mut E)

where E: EntityMapper,

Updates all Entity references stored inside using entity_mapper.

impl<K, V, S> PartialEq for HashMap<K, V, S>

where HashMap<K, V, S>: PartialEq,

fn eq(&self, other: &HashMap<K, V, S>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<K, V, S> PartialReflect for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn into_partial_reflect(self: Box<HashMap<K, V, S>>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &(dyn PartialReflect + 'static)

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut (dyn PartialReflect + 'static)

Casts this type to a mutable, reflected value.

fn try_into_reflect( self: Box<HashMap<K, V, S>>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&(dyn Reflect + 'static)>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut (dyn Reflect + 'static)>

Attempts to cast this type to a mutable, fully-reflected value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<HashMap<K, V, S>>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn reflect_clone(&self) -> Result<Box<dyn Reflect>, ReflectCloneError>

Attempts to clone Self using reflection.

fn reflect_partial_eq( &self, value: &(dyn PartialReflect + 'static), ) -> Option<bool>

Returns a “partial equality” comparison result.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn try_apply( &mut self, value: &(dyn PartialReflect + 'static), ) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn to_dynamic(&self) -> Box<dyn PartialReflect>

Converts this reflected value into its dynamic representation based on its kind.

fn reflect_clone_and_take<T>(&self) -> Result<T, ReflectCloneError>

where T: 'static, Self: Sized + TypePath,

For a type implementing PartialReflect, combines reflect_clone and take in a useful fashion, automatically constructing an appropriate ReflectCloneError if the downcast fails.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

fn debug(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Debug formatter for the value.

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl<K, V> PreHashMapExt<K, V> for HashMap<Hashed<K>, V, PassHash>

where K: Hash + Eq + PartialEq + Clone,

fn get_or_insert_with<F>(&mut self, key: &Hashed<K>, func: F) -> &mut V

where F: FnOnce() -> V,

Tries to get or insert the value for the given key using the pre-computed hash first. If the PreHashMap does not already contain the key, it will clone it and insert the value returned by func.

impl<K, V, S> Reflect for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn into_any(self: Box<HashMap<K, V, S>>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &(dyn Any + 'static)

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<HashMap<K, V, S>>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &(dyn Reflect + 'static)

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut (dyn Reflect + 'static)

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl<K, V, S> Serialize for HashMap<K, V, S>

where HashMap<K, V, S>: Serialize,

fn serialize<T>( &self, serializer: T, ) -> Result<<T as Serializer>::Ok, <T as Serializer>::Error>

where T: Serializer,

Serialize this value into the given Serde serializer.

impl<V> TypeIdMapExt<V> for HashMap<TypeId, V, NoOpHash>

fn insert_type<T>(&mut self, v: V) -> Option<V>

where T: 'static + ?Sized,

Inserts a value for the type T.

fn get_type<T>(&self) -> Option<&V>

where T: 'static + ?Sized,

Returns a reference to the value for type T, if one exists.

fn get_type_mut<T>(&mut self) -> Option<&mut V>

where T: 'static + ?Sized,

Returns a mutable reference to the value for type T, if one exists.

fn remove_type<T>(&mut self) -> Option<V>

where T: 'static + ?Sized,

Removes type T from the map, returning the value for this key if it was previously present.

fn entry_type<T>(&mut self) -> Entry<'_, TypeId, V, NoOpHash>

where T: 'static + ?Sized,

Gets the type T’s entry in the map for in-place manipulation.

impl<K, V, S> TypePath for HashMap<K, V, S>

where HashMap<K, V, S>: Any + Send + Sync, K: TypePath, V: TypePath, S: TypePath,

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

impl<K, V, S> Typed for HashMap<K, V, S>

where K: FromReflect + MaybeTyped + TypePath + GetTypeRegistration + Eq + Hash, V: FromReflect + MaybeTyped + TypePath + GetTypeRegistration, S: TypePath + BuildHasher + Default + Send + Sync,

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.

impl<K, V, S> Eq for HashMap<K, V, S>

where HashMap<K, V, S>: Eq,