Struct StateStore 

pub struct StateStore<Id>
where
    Id: Clone + Eq + Hash + Send + Sync + 'static,
{ /* private fields */ }

Generic state store for managing entity properties with change detection

The store is generic over the entity ID type, allowing it to be used with any identifier (strings, custom IDs, etc.).

Features

• Type-safe property storage and retrieval
• Change detection (only emits events when values actually change)
• Watch pattern (register interest in property changes)
• Blocking iteration over change events

Example

use state_store::{StateStore, Property};

#[derive(Clone, PartialEq, Debug)]
struct Temperature(f32);
impl Property for Temperature {
    const KEY: &'static str = "temperature";
}

let store = StateStore::<String>::new();
let sensor_id = "sensor-1".to_string();

// Watch for temperature changes on sensor-1
store.watch(sensor_id.clone(), Temperature::KEY);

// Set temperature (will emit change event since watched)
store.set(&sensor_id, Temperature(72.5));

// Get current value
let temp = store.get::<Temperature>(&sensor_id);
assert_eq!(temp, Some(Temperature(72.5)));

Implementations

impl<Id> StateStore<Id>

where Id: Clone + Eq + Hash + Send + Sync + 'static,

pub fn new() -> Self

Create a new empty state store

pub fn get<P: Property>(&self, entity_id: &Id) -> Option<P>

Get a property value for an entity

Returns None if the entity doesn’t exist or the property isn’t set.

pub fn set<P: Property>(&self, entity_id: &Id, value: P)

Set a property value for an entity

If the value changes and the property is being watched, a change event is emitted.

pub fn watch(&self, entity_id: Id, property_key: &'static str)

Register interest in a property for an entity

After watching, changes to this property will appear in iter().

pub fn unwatch(&self, entity_id: &Id, property_key: &'static str)

Unregister interest in a property

pub fn is_watched(&self, entity_id: &Id, property_key: &'static str) -> bool

Check if a property is being watched

pub fn iter(&self) -> ChangeIterator<Id>

Create a blocking iterator over change events

Only emits events for properties that have been watched.

pub fn entity_count(&self) -> usize

Get the number of entities in the store

pub fn is_empty(&self) -> bool

Check if the store is empty

pub fn entity_ids(&self) -> Vec<Id>

Get all entity IDs

pub fn remove_entity(&self, entity_id: &Id) -> bool

Remove an entity and all its properties

pub fn clear(&self)

Clear all entities and properties

pub fn event_sender(&self) -> Sender<ChangeEvent<Id>>

Get the event sender for external event injection

This is useful for testing or for injecting events from external sources (e.g., network callbacks).

Trait Implementations

impl<Id> Clone for StateStore<Id>

where Id: Clone + Eq + Hash + Send + Sync + 'static,

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Id> Debug for StateStore<Id>

where Id: Clone + Eq + Hash + Send + Sync + Debug + 'static,

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

Formats the value using the given formatter.

impl<Id> Default for StateStore<Id>

where Id: Clone + Eq + Hash + Send + Sync + 'static,

fn default() -> Self

Returns the “default value” for a type.