Struct Annotated 

pub struct Annotated<T, R>
where
    R: Reducer<T>,
{
    pub value: T,
    /* private fields */
}

Newtype that bundles a value T with the reducer R that should merge it. The wrapper is a standalone helper users compose into their state types; it does not hook into StateGraph::add_node directly.

Fields

value: T

The current value.

Implementations

impl<T, R> Annotated<T, R>

where R: Reducer<T>,

pub const fn new(value: T, reducer: R) -> Self

Wrap value with the supplied reducer.

pub const fn reducer(&self) -> &R

Borrow the inner reducer.

pub fn into_value(self) -> T

Consume the wrapper and return the inner value.

pub fn reduce_in_place(&mut self, update: T)

where T: Default,

Apply the bundled reducer to fold update into self.value.

pub fn reduced(self, update: T) -> Self

where R: Clone,

Consume self, return a new Annotated<T, R> with update folded in.

pub fn merge(self, other: Self) -> Self

Merge two annotated values. Both sides must agree on the reducer type by construction (they share R); the resulting Annotated keeps self’s reducer instance — this matters for stateful reducers, where the current slot’s reducer has the right configuration. Stock reducers (Replace, Append, MergeMap, Max) are unit structs, so the choice is moot for them.

This is the building block the StateMerge derive macro emits per Annotated<T, R> field.

Trait Implementations

impl<T: Clone, R> Clone for Annotated<T, R>

where R: Reducer<T> + Clone,

fn clone(&self) -> Annotated<T, R>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug, R> Debug for Annotated<T, R>

where R: Reducer<T> + Debug,

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

Formats the value using the given formatter.

impl<T, R> Default for Annotated<T, R>

where T: Default, R: Reducer<T> + Default,

fn default() -> Self

Returns the “default value” for a type.