Enum bevy::utils::hashbrown::hash_map::Entry

pub enum Entry<'a, K, V, S, A = Global>
where
    A: Allocator,
{
    Occupied(OccupiedEntry<'a, K, V, S, A>),
    Vacant(VacantEntry<'a, K, V, S, A>),
}

A view into a single entry in a map, which may either be vacant or occupied.

This enum is constructed from the entry method on HashMap.

Examples

use hashbrown::hash_map::{Entry, HashMap, OccupiedEntry};

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

// Existing key (insert)
let entry: Entry<_, _, _> = map.entry("a");
let _raw_o: OccupiedEntry<_, _, _> = entry.insert(1);
assert_eq!(map.len(), 3);
// Nonexistent key (insert)
map.entry("d").insert(4);

// Existing key (or_insert)
let v = map.entry("b").or_insert(2);
assert_eq!(std::mem::replace(v, 2), 20);
// Nonexistent key (or_insert)
map.entry("e").or_insert(5);

// Existing key (or_insert_with)
let v = map.entry("c").or_insert_with(|| 3);
assert_eq!(std::mem::replace(v, 3), 30);
// Nonexistent key (or_insert_with)
map.entry("f").or_insert_with(|| 6);

println!("Our HashMap: {:?}", map);

let mut vec: Vec<_> = map.iter().map(|(&k, &v)| (k, v)).collect();
// 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), ("d", 4), ("e", 5), ("f", 6)]);

Variants

Occupied(OccupiedEntry<'a, K, V, S, A>)

An occupied entry.

Examples

use hashbrown::hash_map::{Entry, HashMap};
let mut map: HashMap<_, _> = [("a", 100), ("b", 200)].into();

match map.entry("a") {
    Entry::Vacant(_) => unreachable!(),
    Entry::Occupied(_) => { }
}

Vacant(VacantEntry<'a, K, V, S, A>)

A vacant entry.

Examples

use hashbrown::hash_map::{Entry, HashMap};
let mut map: HashMap<&str, i32> = HashMap::new();

match map.entry("a") {
    Entry::Occupied(_) => unreachable!(),
    Entry::Vacant(_) => { }
}

Implementations

impl<'a, K, V, S, A> Entry<'a, K, V, S, A>

where A: Allocator,

pub fn insert(self, value: V) -> OccupiedEntry<'a, K, V, S, A>

where K: Hash, S: BuildHasher,

Sets the value of the entry, and returns an OccupiedEntry.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
let entry = map.entry("horseyland").insert(37);

assert_eq!(entry.key(), &"horseyland");

pub fn or_insert(self, default: V) -> &'a mut V

where K: Hash, S: BuildHasher,

Ensures a value is in the entry by inserting the default if empty, and returns a mutable reference to the value in the entry.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();

// nonexistent key
map.entry("poneyland").or_insert(3);
assert_eq!(map["poneyland"], 3);

// existing key
*map.entry("poneyland").or_insert(10) *= 2;
assert_eq!(map["poneyland"], 6);

Examples found in repository

examples/games/contributors.rs (line 324)

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)
}

pub fn or_insert_with<F>(self, default: F) -> &'a mut V

where F: FnOnce() -> V, K: Hash, S: BuildHasher,

Ensures a value is in the entry by inserting the result of the default function if empty, and returns a mutable reference to the value in the entry.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();

// nonexistent key
map.entry("poneyland").or_insert_with(|| 3);
assert_eq!(map["poneyland"], 3);

// existing key
*map.entry("poneyland").or_insert_with(|| 10) *= 2;
assert_eq!(map["poneyland"], 6);

pub fn or_insert_with_key<F>(self, default: F) -> &'a mut V

where F: FnOnce(&K) -> V, K: Hash, S: BuildHasher,

Ensures a value is in the entry by inserting, if empty, the result of the default function. This method allows for generating key-derived values for insertion by providing the default function a reference to the key that was moved during the .entry(key) method call.

The reference to the moved key is provided so that cloning or copying the key is unnecessary, unlike with .or_insert_with(|| ... ).

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, usize> = HashMap::new();

// nonexistent key
map.entry("poneyland").or_insert_with_key(|key| key.chars().count());
assert_eq!(map["poneyland"], 9);

// existing key
*map.entry("poneyland").or_insert_with_key(|key| key.chars().count() * 10) *= 2;
assert_eq!(map["poneyland"], 18);

pub fn key(&self) -> &K

Returns a reference to this entry’s key.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(3);
// existing key
assert_eq!(map.entry("poneyland").key(), &"poneyland");
// nonexistent key
assert_eq!(map.entry("horseland").key(), &"horseland");

pub fn and_modify<F>(self, f: F) -> Entry<'a, K, V, S, A>

where F: FnOnce(&mut V),

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();

map.entry("poneyland")
   .and_modify(|e| { *e += 1 })
   .or_insert(42);
assert_eq!(map["poneyland"], 42);

map.entry("poneyland")
   .and_modify(|e| { *e += 1 })
   .or_insert(42);
assert_eq!(map["poneyland"], 43);

pub fn and_replace_entry_with<F>(self, f: F) -> Entry<'a, K, V, S, A>

where F: FnOnce(&K, V) -> Option<V>,

Provides shared access to the key and owned access to the value of an occupied entry and allows to replace or remove it based on the value of the returned option.

Examples

use hashbrown::HashMap;
use hashbrown::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();

let entry = map
    .entry("poneyland")
    .and_replace_entry_with(|_k, _v| panic!());

match entry {
    Entry::Vacant(e) => {
        assert_eq!(e.key(), &"poneyland");
    }
    Entry::Occupied(_) => panic!(),
}

map.insert("poneyland", 42);

let entry = map
    .entry("poneyland")
    .and_replace_entry_with(|k, v| {
        assert_eq!(k, &"poneyland");
        assert_eq!(v, 42);
        Some(v + 1)
    });

match entry {
    Entry::Occupied(e) => {
        assert_eq!(e.key(), &"poneyland");
        assert_eq!(e.get(), &43);
    }
    Entry::Vacant(_) => panic!(),
}

assert_eq!(map["poneyland"], 43);

let entry = map
    .entry("poneyland")
    .and_replace_entry_with(|_k, _v| None);

match entry {
    Entry::Vacant(e) => assert_eq!(e.key(), &"poneyland"),
    Entry::Occupied(_) => panic!(),
}

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

impl<'a, K, V, S, A> Entry<'a, K, V, S, A>

where V: Default, A: Allocator,

pub fn or_default(self) -> &'a mut V

where K: Hash, S: BuildHasher,

Ensures a value is in the entry by inserting the default value if empty, and returns a mutable reference to the value in the entry.

Examples

use hashbrown::HashMap;

let mut map: HashMap<&str, Option<u32>> = HashMap::new();

// nonexistent key
map.entry("poneyland").or_default();
assert_eq!(map["poneyland"], None);

map.insert("horseland", Some(3));

// existing key
assert_eq!(map.entry("horseland").or_default(), &mut Some(3));

Examples found in repository

examples/tools/scene_viewer/animation_plugin.rs (line 129)

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);
    }
}

Trait Implementations

impl<K, V, S, A> Debug for Entry<'_, K, V, S, A>

where K: Debug, V: Debug, A: Allocator,

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

Formats the value using the given formatter.