Struct bevy::sprite::RenderMaterial2dInstances

pub struct RenderMaterial2dInstances<M>(/* private fields */)
where
    M: Material2d;

Methods from Deref<Target = HashMap<Entity, AssetId<M>, EntityHash>>§

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::hash_map::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);
Examples found in repository?
examples/tools/scene_viewer/animation_plugin.rs (line 63)
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fn assign_clips(
    mut players: Query<&mut AnimationPlayer>,
    targets: Query<(Entity, &AnimationTarget)>,
    parents: Query<&Parent>,
    scene_handle: Res<SceneHandle>,
    clips: Res<Assets<AnimationClip>>,
    gltf_assets: Res<Assets<Gltf>>,
    assets: Res<AssetServer>,
    mut graphs: ResMut<Assets<AnimationGraph>>,
    mut commands: Commands,
    mut setup: Local<bool>,
) {
    if scene_handle.is_loaded && !*setup {
        *setup = true;
    } else {
        return;
    }

    let gltf = gltf_assets.get(&scene_handle.gltf_handle).unwrap();
    let animations = &gltf.animations;
    if animations.is_empty() {
        return;
    }

    let count = animations.len();
    let plural = if count == 1 { "" } else { "s" };
    info!("Found {} animation{plural}", animations.len());
    let names: Vec<_> = gltf.named_animations.keys().collect();
    info!("Animation names: {names:?}");

    // Map animation target IDs to entities.
    let animation_target_id_to_entity: HashMap<_, _> = targets
        .iter()
        .map(|(entity, target)| (target.id, entity))
        .collect();

    // Build up a list of all animation clips that belong to each player. A clip
    // is considered to belong to an animation player if all targets of the clip
    // refer to entities whose nearest ancestor player is that animation player.

    let mut player_to_graph: EntityHashMap<(AnimationGraph, Vec<AnimationNodeIndex>)> =
        EntityHashMap::default();

    for (clip_id, clip) in clips.iter() {
        let mut ancestor_player = None;
        for target_id in clip.curves().keys() {
            // If the animation clip refers to entities that aren't present in
            // the scene, bail.
            let Some(&target) = animation_target_id_to_entity.get(target_id) else {
                continue;
            };

            // Find the nearest ancestor animation player.
            let mut current = Some(target);
            while let Some(entity) = current {
                if players.contains(entity) {
                    match ancestor_player {
                        None => {
                            // If we haven't found a player yet, record the one
                            // we found.
                            ancestor_player = Some(entity);
                        }
                        Some(ancestor) => {
                            // If we have found a player, then make sure it's
                            // the same player we located before.
                            if ancestor != entity {
                                // It's a different player. Bail.
                                ancestor_player = None;
                                break;
                            }
                        }
                    }
                }

                // Go to the next parent.
                current = parents.get(entity).ok().map(|parent| parent.get());
            }
        }

        let Some(ancestor_player) = ancestor_player else {
            warn!(
                "Unexpected animation hierarchy for animation clip {:?}; ignoring.",
                clip_id
            );
            continue;
        };

        let Some(clip_handle) = assets.get_id_handle(clip_id) else {
            warn!("Clip {:?} wasn't loaded.", clip_id);
            continue;
        };

        let &mut (ref mut graph, ref mut clip_indices) =
            player_to_graph.entry(ancestor_player).or_default();
        let node_index = graph.add_clip(clip_handle, 1.0, graph.root);
        clip_indices.push(node_index);
    }

    // Now that we've built up a list of all clips that belong to each player,
    // package them up into a `Clips` component, play the first such animation,
    // and add that component to the player.
    for (player_entity, (graph, clips)) in player_to_graph {
        let Ok(mut player) = players.get_mut(player_entity) else {
            warn!("Animation targets referenced a nonexistent player. This shouldn't happen.");
            continue;
        };
        let graph = graphs.add(graph);
        let animations = Clips::new(clips);
        player.play(animations.current()).repeat();
        commands
            .entity(player_entity)
            .insert(animations)
            .insert(graph);
    }
}

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);
Examples found in repository?
examples/3d/tonemapping.rs (line 401)
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fn update_color_grading_settings(
    keys: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
    mut per_method_settings: ResMut<PerMethodSettings>,
    tonemapping: Query<&Tonemapping>,
    current_scene: Res<CurrentScene>,
    mut selected_parameter: ResMut<SelectedParameter>,
) {
    let method = tonemapping.single();
    let color_grading = per_method_settings.settings.get_mut(method).unwrap();
    let mut dt = time.delta_seconds() * 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.

§Examples
use hashbrown::HashMap;

let mut a = HashMap::new();
assert_eq!(a.len(), 0);
a.insert(1, "a");
assert_eq!(a.len(), 1);
Examples found in repository?
examples/stress_tests/many_lights.rs (line 181)
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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()
        );
    }
}
More examples
Hide additional examples
examples/games/contributors.rs (line 82)
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fn setup_contributor_selection(mut commands: Commands, asset_server: Res<AssetServer>) {
    // Load contributors from the git history log or use default values from
    // the constant array. Contributors are stored in a HashMap with their
    // commit count.
    let contribs = contributors().unwrap_or_else(|_| {
        CONTRIBUTORS_LIST
            .iter()
            .map(|name| (name.to_string(), 1))
            .collect()
    });

    let texture_handle = asset_server.load("branding/icon.png");

    let mut contributor_selection = ContributorSelection {
        order: Vec::with_capacity(contribs.len()),
        idx: 0,
    };

    let mut rng = rand::thread_rng();

    for (name, num_commits) in contribs {
        let transform =
            Transform::from_xyz(rng.gen_range(-400.0..400.0), rng.gen_range(0.0..400.0), 0.0);
        let dir = rng.gen_range(-1.0..1.0);
        let velocity = Vec3::new(dir * 500.0, 0.0, 0.0);
        let hue = name_to_hue(&name);

        // Some sprites should be flipped for variety
        let flipped = rng.gen();

        let entity = commands
            .spawn((
                Contributor {
                    name,
                    num_commits,
                    hue,
                },
                Velocity {
                    translation: velocity,
                    rotation: -dir * 5.0,
                },
                SpriteBundle {
                    sprite: Sprite {
                        custom_size: Some(Vec2::splat(SPRITE_SIZE)),
                        color: DESELECTED.with_hue(hue).into(),
                        flip_x: flipped,
                        ..default()
                    },
                    texture: texture_handle.clone(),
                    transform,
                    ..default()
                },
            ))
            .id();

        contributor_selection.order.push(entity);
    }

    contributor_selection.order.shuffle(&mut rng);

    commands.insert_resource(contributor_selection);
}

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());
Examples found in repository?
examples/2d/mesh2d_manual.rs (line 360)
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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>,
    msaa: Res<Msaa>,
    render_meshes: Res<RenderAssets<GpuMesh>>,
    render_mesh_instances: Res<RenderColoredMesh2dInstances>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent2d>>,
    mut views: Query<(Entity, &VisibleEntities, &ExtractedView)>,
) {
    if render_mesh_instances.is_empty() {
        return;
    }
    // Iterate each view (a camera is a view)
    for (view_entity, visible_entities, view) in &mut views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&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 visible_entity in visible_entities.iter::<WithMesh2d>() {
            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;
                if let Some(mesh) = render_meshes.get(mesh2d_handle) {
                    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: *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,
                });
            }
        }
    }
}

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);
Examples found in repository?
examples/ecs/observers.rs (line 129)
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fn on_add_mine(
    trigger: Trigger<OnAdd, Mine>,
    query: Query<&Mine>,
    mut index: ResMut<SpatialIndex>,
) {
    let mine = query.get(trigger.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(trigger.entity());
}

// Remove despawned mines from our index
fn on_remove_mine(
    trigger: Trigger<OnRemove, Mine>,
    query: Query<&Mine>,
    mut index: ResMut<SpatialIndex>,
) {
    let mine = query.get(trigger.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(&trigger.entity());
    });
}
More examples
Hide additional examples
examples/games/contributors.rs (line 324)
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fn contributors() -> Result<Contributors, LoadContributorsError> {
    let manifest_dir = std::env::var("CARGO_MANIFEST_DIR")?;

    let mut cmd = std::process::Command::new("git")
        .args(["--no-pager", "log", "--pretty=format:%an"])
        .current_dir(manifest_dir)
        .stdout(Stdio::piped())
        .spawn()?;

    let stdout = cmd.stdout.take().ok_or(LoadContributorsError::Stdout)?;

    // Take the list of commit author names and collect them into a HashMap,
    // keeping a count of how many commits they authored.
    let contributors = BufReader::new(stdout).lines().map_while(Result::ok).fold(
        HashMap::new(),
        |mut acc, word| {
            *acc.entry(word).or_insert(0) += 1;
            acc
        },
    );

    Ok(contributors)
}
examples/tools/scene_viewer/animation_plugin.rs (line 129)
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fn assign_clips(
    mut players: Query<&mut AnimationPlayer>,
    targets: Query<(Entity, &AnimationTarget)>,
    parents: Query<&Parent>,
    scene_handle: Res<SceneHandle>,
    clips: Res<Assets<AnimationClip>>,
    gltf_assets: Res<Assets<Gltf>>,
    assets: Res<AssetServer>,
    mut graphs: ResMut<Assets<AnimationGraph>>,
    mut commands: Commands,
    mut setup: Local<bool>,
) {
    if scene_handle.is_loaded && !*setup {
        *setup = true;
    } else {
        return;
    }

    let gltf = gltf_assets.get(&scene_handle.gltf_handle).unwrap();
    let animations = &gltf.animations;
    if animations.is_empty() {
        return;
    }

    let count = animations.len();
    let plural = if count == 1 { "" } else { "s" };
    info!("Found {} animation{plural}", animations.len());
    let names: Vec<_> = gltf.named_animations.keys().collect();
    info!("Animation names: {names:?}");

    // Map animation target IDs to entities.
    let animation_target_id_to_entity: HashMap<_, _> = targets
        .iter()
        .map(|(entity, target)| (target.id, entity))
        .collect();

    // Build up a list of all animation clips that belong to each player. A clip
    // is considered to belong to an animation player if all targets of the clip
    // refer to entities whose nearest ancestor player is that animation player.

    let mut player_to_graph: EntityHashMap<(AnimationGraph, Vec<AnimationNodeIndex>)> =
        EntityHashMap::default();

    for (clip_id, clip) in clips.iter() {
        let mut ancestor_player = None;
        for target_id in clip.curves().keys() {
            // If the animation clip refers to entities that aren't present in
            // the scene, bail.
            let Some(&target) = animation_target_id_to_entity.get(target_id) else {
                continue;
            };

            // Find the nearest ancestor animation player.
            let mut current = Some(target);
            while let Some(entity) = current {
                if players.contains(entity) {
                    match ancestor_player {
                        None => {
                            // If we haven't found a player yet, record the one
                            // we found.
                            ancestor_player = Some(entity);
                        }
                        Some(ancestor) => {
                            // If we have found a player, then make sure it's
                            // the same player we located before.
                            if ancestor != entity {
                                // It's a different player. Bail.
                                ancestor_player = None;
                                break;
                            }
                        }
                    }
                }

                // Go to the next parent.
                current = parents.get(entity).ok().map(|parent| parent.get());
            }
        }

        let Some(ancestor_player) = ancestor_player else {
            warn!(
                "Unexpected animation hierarchy for animation clip {:?}; ignoring.",
                clip_id
            );
            continue;
        };

        let Some(clip_handle) = assets.get_id_handle(clip_id) else {
            warn!("Clip {:?} wasn't loaded.", clip_id);
            continue;
        };

        let &mut (ref mut graph, ref mut clip_indices) =
            player_to_graph.entry(ancestor_player).or_default();
        let node_index = graph.add_clip(clip_handle, 1.0, graph.root);
        clip_indices.push(node_index);
    }

    // Now that we've built up a list of all clips that belong to each player,
    // package them up into a `Clips` component, play the first such animation,
    // and add that component to the player.
    for (player_entity, (graph, clips)) in player_to_graph {
        let Ok(mut player) = players.get_mut(player_entity) else {
            warn!("Animation targets referenced a nonexistent player. This shouldn't happen.");
            continue;
        };
        let graph = graphs.add(graph);
        let animations = Clips::new(clips);
        player.play(animations.current()).repeat();
        commands
            .entity(player_entity)
            .insert(animations)
            .insert(graph);
    }
}

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);
Examples found in repository?
examples/ecs/observers.rs (line 213)
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    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
    }
More examples
Hide additional examples
examples/3d/tonemapping.rs (line 336)
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fn toggle_tonemapping_method(
    keys: Res<ButtonInput<KeyCode>>,
    mut tonemapping: Query<&mut Tonemapping>,
    mut color_grading: Query<&mut ColorGrading>,
    per_method_settings: Res<PerMethodSettings>,
) {
    let mut method = tonemapping.single_mut();
    let mut color_grading = color_grading.single_mut();

    if keys.just_pressed(KeyCode::Digit1) {
        *method = Tonemapping::None;
    } else if keys.just_pressed(KeyCode::Digit2) {
        *method = Tonemapping::Reinhard;
    } else if keys.just_pressed(KeyCode::Digit3) {
        *method = Tonemapping::ReinhardLuminance;
    } else if keys.just_pressed(KeyCode::Digit4) {
        *method = Tonemapping::AcesFitted;
    } else if keys.just_pressed(KeyCode::Digit5) {
        *method = Tonemapping::AgX;
    } else if keys.just_pressed(KeyCode::Digit6) {
        *method = Tonemapping::SomewhatBoringDisplayTransform;
    } else if keys.just_pressed(KeyCode::Digit7) {
        *method = Tonemapping::TonyMcMapface;
    } else if keys.just_pressed(KeyCode::Digit8) {
        *method = Tonemapping::BlenderFilmic;
    }

    *color_grading = (*per_method_settings
        .settings
        .get::<Tonemapping>(&method)
        .as_ref()
        .unwrap())
    .clone();
}
examples/2d/mesh2d_manual.rs (line 376)
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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>,
    msaa: Res<Msaa>,
    render_meshes: Res<RenderAssets<GpuMesh>>,
    render_mesh_instances: Res<RenderColoredMesh2dInstances>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent2d>>,
    mut views: Query<(Entity, &VisibleEntities, &ExtractedView)>,
) {
    if render_mesh_instances.is_empty() {
        return;
    }
    // Iterate each view (a camera is a view)
    for (view_entity, visible_entities, view) in &mut views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&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 visible_entity in visible_entities.iter::<WithMesh2d>() {
            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;
                if let Some(mesh) = render_meshes.get(mesh2d_handle) {
                    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: *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,
                });
            }
        }
    }
}
examples/ecs/dynamic.rs (line 114)
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fn main() {
    let mut world = World::new();
    let mut lines = std::io::stdin().lines();
    let mut component_names = HashMap::<String, ComponentId>::new();
    let mut component_info = HashMap::<ComponentId, ComponentInfo>::new();

    println!("{}", PROMPT);
    loop {
        print!("\n> ");
        let _ = std::io::stdout().flush();
        let Some(Ok(line)) = lines.next() else {
            return;
        };

        if line.is_empty() {
            return;
        };

        let Some((first, rest)) = line.trim().split_once(|c: char| c.is_whitespace()) else {
            match &line.chars().next() {
                Some('c') => println!("{}", COMPONENT_PROMPT),
                Some('s') => println!("{}", ENTITY_PROMPT),
                Some('q') => println!("{}", QUERY_PROMPT),
                _ => println!("{}", PROMPT),
            }
            continue;
        };

        match &first[0..1] {
            "c" => {
                rest.split(',').for_each(|component| {
                    let mut component = component.split_whitespace();
                    let Some(name) = component.next() else {
                        return;
                    };
                    let size = match component.next().map(|s| s.parse::<usize>()) {
                        Some(Ok(size)) => size,
                        _ => 0,
                    };
                    // Register our new component to the world with a layout specified by it's size
                    // SAFETY: [u64] is Send + Sync
                    let id = world.init_component_with_descriptor(unsafe {
                        ComponentDescriptor::new_with_layout(
                            name.to_string(),
                            StorageType::Table,
                            Layout::array::<u64>(size).unwrap(),
                            None,
                        )
                    });
                    let Some(info) = world.components().get_info(id) else {
                        return;
                    };
                    component_names.insert(name.to_string(), id);
                    component_info.insert(id, info.clone());
                    println!("Component {} created with id: {:?}", name, id.index());
                });
            }
            "s" => {
                let mut to_insert_ids = Vec::new();
                let mut to_insert_data = Vec::new();
                rest.split(',').for_each(|component| {
                    let mut component = component.split_whitespace();
                    let Some(name) = component.next() else {
                        return;
                    };

                    // Get the id for the component with the given name
                    let Some(&id) = component_names.get(name) else {
                        println!("Component {} does not exist", name);
                        return;
                    };

                    // Calculate the length for the array based on the layout created for this component id
                    let info = world.components().get_info(id).unwrap();
                    let len = info.layout().size() / std::mem::size_of::<u64>();
                    let mut values: Vec<u64> = component
                        .take(len)
                        .filter_map(|value| value.parse::<u64>().ok())
                        .collect();
                    values.resize(len, 0);

                    // Collect the id and array to be inserted onto our entity
                    to_insert_ids.push(id);
                    to_insert_data.push(values);
                });

                let mut entity = world.spawn_empty();

                // Construct an `OwningPtr` for each component in `to_insert_data`
                let to_insert_ptr = to_owning_ptrs(&mut to_insert_data);

                // SAFETY:
                // - Component ids have been taken from the same world
                // - Each array is created to the layout specified in the world
                unsafe {
                    entity.insert_by_ids(&to_insert_ids, to_insert_ptr.into_iter());
                }

                println!("Entity spawned with id: {:?}", entity.id());
            }
            "q" => {
                let mut builder = QueryBuilder::<FilteredEntityMut>::new(&mut world);
                parse_query(rest, &mut builder, &component_names);
                let mut query = builder.build();

                query.iter_mut(&mut world).for_each(|filtered_entity| {
                    let terms = filtered_entity
                        .components()
                        .map(|id| {
                            let ptr = filtered_entity.get_by_id(id).unwrap();
                            let info = component_info.get(&id).unwrap();
                            let len = info.layout().size() / std::mem::size_of::<u64>();

                            // SAFETY:
                            // - All components are created with layout [u64]
                            // - len is calculated from the component descriptor
                            let data = unsafe {
                                std::slice::from_raw_parts_mut(
                                    ptr.assert_unique().as_ptr().cast::<u64>(),
                                    len,
                                )
                            };

                            // If we have write access, increment each value once
                            if filtered_entity.access().has_write(id) {
                                data.iter_mut().for_each(|data| {
                                    *data += 1;
                                });
                            }

                            format!("{}: {:?}", info.name(), data[0..len].to_vec())
                        })
                        .collect::<Vec<_>>()
                        .join(", ");

                    println!("{:?}: {}", filtered_entity.id(), terms);
                });
            }
            _ => continue,
        }
    }
}

// Constructs `OwningPtr` for each item in `components`
// By sharing the lifetime of `components` with the resulting ptrs we ensure we don't drop the data before use
fn to_owning_ptrs(components: &mut [Vec<u64>]) -> Vec<OwningPtr<Aligned>> {
    components
        .iter_mut()
        .map(|data| {
            let ptr = data.as_mut_ptr();
            // SAFETY:
            // - Pointers are guaranteed to be non-null
            // - Memory pointed to won't be dropped until `components` is dropped
            unsafe {
                let non_null = NonNull::new_unchecked(ptr.cast());
                OwningPtr::new(non_null)
            }
        })
        .collect()
}

fn parse_term<Q: QueryData>(
    str: &str,
    builder: &mut QueryBuilder<Q>,
    components: &HashMap<String, ComponentId>,
) {
    let mut matched = false;
    let str = str.trim();
    match str.chars().next() {
        // Optional term
        Some('?') => {
            builder.optional(|b| parse_term(&str[1..], b, components));
            matched = true;
        }
        // Reference term
        Some('&') => {
            let mut parts = str.split_whitespace();
            let first = parts.next().unwrap();
            if first == "&mut" {
                if let Some(str) = parts.next() {
                    if let Some(&id) = components.get(str) {
                        builder.mut_id(id);
                        matched = true;
                    }
                };
            } else if let Some(&id) = components.get(&first[1..]) {
                builder.ref_id(id);
                matched = true;
            }
        }
        // With term
        Some(_) => {
            if let Some(&id) = components.get(str) {
                builder.with_id(id);
                matched = true;
            }
        }
        None => {}
    };

    if !matched {
        println!("Unable to find component: {}", str);
    }
}

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);
Examples found in repository?
examples/3d/tonemapping.rs (line 366)
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fn update_color_grading_settings(
    keys: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
    mut per_method_settings: ResMut<PerMethodSettings>,
    tonemapping: Query<&Tonemapping>,
    current_scene: Res<CurrentScene>,
    mut selected_parameter: ResMut<SelectedParameter>,
) {
    let method = tonemapping.single();
    let color_grading = per_method_settings.settings.get_mut(method).unwrap();
    let mut dt = time.delta_seconds() * 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);
        }
    }
}
More examples
Hide additional examples
examples/shader/shader_instancing.rs (line 131)
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fn queue_custom(
    transparent_3d_draw_functions: Res<DrawFunctions<Transparent3d>>,
    custom_pipeline: Res<CustomPipeline>,
    msaa: Res<Msaa>,
    mut pipelines: ResMut<SpecializedMeshPipelines<CustomPipeline>>,
    pipeline_cache: Res<PipelineCache>,
    meshes: Res<RenderAssets<GpuMesh>>,
    render_mesh_instances: Res<RenderMeshInstances>,
    material_meshes: Query<Entity, With<InstanceMaterialData>>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent3d>>,
    mut views: Query<(Entity, &ExtractedView)>,
) {
    let draw_custom = transparent_3d_draw_functions.read().id::<DrawCustom>();

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

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

        let view_key = msaa_key | MeshPipelineKey::from_hdr(view.hdr);
        let rangefinder = view.rangefinder3d();
        for entity in &material_meshes {
            let Some(mesh_instance) = render_mesh_instances.render_mesh_queue_data(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,
                pipeline,
                draw_function: draw_custom,
                distance: rangefinder.distance_translation(&mesh_instance.translation),
                batch_range: 0..1,
                extra_index: PhaseItemExtraIndex::NONE,
            });
        }
    }
}
examples/2d/mesh2d_manual.rs (line 365)
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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>,
    msaa: Res<Msaa>,
    render_meshes: Res<RenderAssets<GpuMesh>>,
    render_mesh_instances: Res<RenderColoredMesh2dInstances>,
    mut transparent_render_phases: ResMut<ViewSortedRenderPhases<Transparent2d>>,
    mut views: Query<(Entity, &VisibleEntities, &ExtractedView)>,
) {
    if render_mesh_instances.is_empty() {
        return;
    }
    // Iterate each view (a camera is a view)
    for (view_entity, visible_entities, view) in &mut views {
        let Some(transparent_phase) = transparent_render_phases.get_mut(&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 visible_entity in visible_entities.iter::<WithMesh2d>() {
            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;
                if let Some(mesh) = render_meshes.get(mesh2d_handle) {
                    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: *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,
                });
            }
        }
    }
}

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 returned if any of the keys are duplicates or missing.

§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_mut([
    "Athenæum",
    "Library of Congress",
]);
assert_eq!(
    got,
    Some([
        &mut 1807,
        &mut 1800,
    ]),
);

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

// Duplicate keys result in None
let got = libraries.get_many_mut([
    "Athenæum",
    "Athenæum",
]);
assert_eq!(got, None);

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 returned if any of the keys are 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);

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

// Missing keys result in None
let got = libraries.get_many_mut([
    "Athenæum",
    "New York Public Library",
]);
assert_eq!(got, 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 returned if any of the keys are duplicates or missing.

§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),
        (&"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, None);

// Duplicate keys result in None
let got = libraries.get_many_key_value_mut([
    "Bodleian Library",
    "Herzogin-Anna-Amalia-Bibliothek",
    "Herzogin-Anna-Amalia-Bibliothek",
]);
assert_eq!(got, None);

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),
        (&"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, 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");
Examples found in repository?
examples/3d/tonemapping.rs (lines 594-597)
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    fn default() -> Self {
        let mut settings = HashMap::new();

        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 }
    }
More examples
Hide additional examples
examples/2d/mesh2d_manual.rs (lines 333-341)
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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, &ViewVisibility, &GlobalTransform, &Mesh2dHandle), With<ColoredMesh2d>>,
    >,
    mut render_mesh_instances: ResMut<RenderColoredMesh2dInstances>,
) {
    let mut values = Vec::with_capacity(*previous_len);
    for (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((entity, ColoredMesh2d));
        render_mesh_instances.insert(
            entity,
            RenderMesh2dInstance {
                mesh_asset_id: handle.0.id(),
                transforms,
                material_bind_group_id: Material2dBindGroupId::default(),
                automatic_batching: false,
            },
        );
    }
    *previous_len = values.len();
    commands.insert_or_spawn_batch(values);
}
examples/reflection/reflection_types.rs (line 67)
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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(_) => {}
        // `Value` types do not implement any of the other traits above. They are simply a Reflect
        // implementation. Value is implemented for core types like i32, usize, f32, and
        // String.
        ReflectRef::Value(_) => {}
    }

    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]);
}
examples/ecs/dynamic.rs (line 99)
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fn main() {
    let mut world = World::new();
    let mut lines = std::io::stdin().lines();
    let mut component_names = HashMap::<String, ComponentId>::new();
    let mut component_info = HashMap::<ComponentId, ComponentInfo>::new();

    println!("{}", PROMPT);
    loop {
        print!("\n> ");
        let _ = std::io::stdout().flush();
        let Some(Ok(line)) = lines.next() else {
            return;
        };

        if line.is_empty() {
            return;
        };

        let Some((first, rest)) = line.trim().split_once(|c: char| c.is_whitespace()) else {
            match &line.chars().next() {
                Some('c') => println!("{}", COMPONENT_PROMPT),
                Some('s') => println!("{}", ENTITY_PROMPT),
                Some('q') => println!("{}", QUERY_PROMPT),
                _ => println!("{}", PROMPT),
            }
            continue;
        };

        match &first[0..1] {
            "c" => {
                rest.split(',').for_each(|component| {
                    let mut component = component.split_whitespace();
                    let Some(name) = component.next() else {
                        return;
                    };
                    let size = match component.next().map(|s| s.parse::<usize>()) {
                        Some(Ok(size)) => size,
                        _ => 0,
                    };
                    // Register our new component to the world with a layout specified by it's size
                    // SAFETY: [u64] is Send + Sync
                    let id = world.init_component_with_descriptor(unsafe {
                        ComponentDescriptor::new_with_layout(
                            name.to_string(),
                            StorageType::Table,
                            Layout::array::<u64>(size).unwrap(),
                            None,
                        )
                    });
                    let Some(info) = world.components().get_info(id) else {
                        return;
                    };
                    component_names.insert(name.to_string(), id);
                    component_info.insert(id, info.clone());
                    println!("Component {} created with id: {:?}", name, id.index());
                });
            }
            "s" => {
                let mut to_insert_ids = Vec::new();
                let mut to_insert_data = Vec::new();
                rest.split(',').for_each(|component| {
                    let mut component = component.split_whitespace();
                    let Some(name) = component.next() else {
                        return;
                    };

                    // Get the id for the component with the given name
                    let Some(&id) = component_names.get(name) else {
                        println!("Component {} does not exist", name);
                        return;
                    };

                    // Calculate the length for the array based on the layout created for this component id
                    let info = world.components().get_info(id).unwrap();
                    let len = info.layout().size() / std::mem::size_of::<u64>();
                    let mut values: Vec<u64> = component
                        .take(len)
                        .filter_map(|value| value.parse::<u64>().ok())
                        .collect();
                    values.resize(len, 0);

                    // Collect the id and array to be inserted onto our entity
                    to_insert_ids.push(id);
                    to_insert_data.push(values);
                });

                let mut entity = world.spawn_empty();

                // Construct an `OwningPtr` for each component in `to_insert_data`
                let to_insert_ptr = to_owning_ptrs(&mut to_insert_data);

                // SAFETY:
                // - Component ids have been taken from the same world
                // - Each array is created to the layout specified in the world
                unsafe {
                    entity.insert_by_ids(&to_insert_ids, to_insert_ptr.into_iter());
                }

                println!("Entity spawned with id: {:?}", entity.id());
            }
            "q" => {
                let mut builder = QueryBuilder::<FilteredEntityMut>::new(&mut world);
                parse_query(rest, &mut builder, &component_names);
                let mut query = builder.build();

                query.iter_mut(&mut world).for_each(|filtered_entity| {
                    let terms = filtered_entity
                        .components()
                        .map(|id| {
                            let ptr = filtered_entity.get_by_id(id).unwrap();
                            let info = component_info.get(&id).unwrap();
                            let len = info.layout().size() / std::mem::size_of::<u64>();

                            // SAFETY:
                            // - All components are created with layout [u64]
                            // - len is calculated from the component descriptor
                            let data = unsafe {
                                std::slice::from_raw_parts_mut(
                                    ptr.assert_unique().as_ptr().cast::<u64>(),
                                    len,
                                )
                            };

                            // If we have write access, increment each value once
                            if filtered_entity.access().has_write(id) {
                                data.iter_mut().for_each(|data| {
                                    *data += 1;
                                });
                            }

                            format!("{}: {:?}", info.name(), data[0..len].to_vec())
                        })
                        .collect::<Vec<_>>()
                        .join(", ");

                    println!("{:?}: {}", filtered_entity.id(), terms);
                });
            }
            _ => continue,
        }
    }
}

pub 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.

Returns a reference to the key and value just inserted.

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.

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.

§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() {
    map2.insert_unique_unchecked(key, value);
}

let (key, value) = 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 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);
}

pub fn raw_table(&self) -> &RawTable<(K, V), A>

Available on crate feature raw only.

Returns a reference to the RawTable used underneath HashMap. This function is only available if the raw feature of the crate is enabled.

See raw_table_mut for more.

pub fn raw_table_mut(&mut self) -> &mut RawTable<(K, V), A>

Available on crate feature raw only.

Returns a mutable reference to the RawTable used underneath HashMap. This function is only available if the raw feature of the crate is enabled.

§Note

Calling this function is safe, but using the raw hash table API may require unsafe functions or blocks.

RawTable API gives the lowest level of control under the map that can be useful for extending the HashMap’s API, but may lead to undefined behavior.

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

let mut map = HashMap::new();
map.extend([("a", 10), ("b", 20), ("c", 30)]);
assert_eq!(map.len(), 3);

// Let's imagine that we have a value and a hash of the key, but not the key itself.
// However, if you want to remove the value from the map by hash and value, and you
// know exactly that the value is unique, then you can create a function like this:
fn remove_by_hash<K, V, S, F>(
    map: &mut HashMap<K, V, S>,
    hash: u64,
    is_match: F,
) -> Option<(K, V)>
where
    F: Fn(&(K, V)) -> bool,
{
    let raw_table = map.raw_table_mut();
    match raw_table.find(hash, is_match) {
        Some(bucket) => Some(unsafe { raw_table.remove(bucket).0 }),
        None => None,
    }
}

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()
}

let hash = compute_hash(map.hasher(), "a");
assert_eq!(remove_by_hash(&mut map, hash, |(_, v)| *v == 10), Some(("a", 10)));
assert_eq!(map.get(&"a"), None);
assert_eq!(map.len(), 2);

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