Struct SystemState 

pub struct SystemState { /* private fields */ }

A heterogeneous collection of payloads describing one system time point.

Fields are declared by a JSON-derived StateSpec. Values are addressed by those field names but stored in compact optional slots. The type-erased representation remains private; callers always insert, borrow, mutate, and extract concrete Rust types.

Implementations

impl SystemState

pub fn empty(&self, time: TimePoint) -> Self

Creates another empty state with the same shared specification.

No payload is cloned. Only the immutable specification handle is cloned, which increments an internal Arc reference count.

pub const fn time(&self) -> TimePoint

Returns this state’s temporal coordinate.

pub const fn spec(&self) -> &StateSpec

Returns the shared immutable field specification.

pub fn len(&self) -> usize

Returns the number of fields declared by the state specification.

This count is structural and includes empty payload slots.

pub fn is_empty(&self) -> bool

Reports whether the state specification declares no fields.

This is consistent with SystemState::len. To test whether a non-empty layout currently carries no payloads, use SystemState::is_blank.

pub fn loaded(&self) -> usize

Returns the number of slots that currently contain payloads.

pub fn is_blank(&self) -> bool

Reports whether every declared payload slot is empty.

pub fn fields(&self) -> &[FieldSpec]

Returns field specifications in deterministic template order.

pub fn has(&self, key: &str) -> Result<bool, StateError>

Reports whether a declared field currently contains a payload.

Errors

Returns StateError::UnknownField when key was not declared by the JSON template.

pub fn is<T>(&self, key: &str) -> Result<bool, StateError>

where T: Any,

Reports whether a populated field contains the exact Rust type T.

An empty declared field returns false.

Errors

Returns StateError::UnknownField when key was not declared by the JSON template.

pub fn set<T>(&mut self, key: &str, payload: T) -> Result<(), StateError>

where T: Any + Clone + Send,

Sets or replaces the payload in a declared field.

payload moves into the state and is never cloned. If the slot was already populated, its previous value is dropped. Call take first when the previous payload must be retained.

Errors

Returns StateError::UnknownField when key was not declared by the JSON template. The payload is dropped with the returned error because this minimal API does not expose the internal erased-value wrapper.

pub fn get<T>(&self, key: &str) -> Result<&T, StateError>

where T: Any,

Borrows a populated field as the exact Rust type T.

Errors

Returns StateError::UnknownField for an undeclared key, StateError::MissingValue for an empty slot, or StateError::TypeMismatch when the stored concrete type differs from T.

pub fn get_mut<T>(&mut self, key: &str) -> Result<&mut T, StateError>

where T: Any,

Mutably borrows a populated field as the exact Rust type T.

Mutation occurs in place and does not clone the payload.

Errors

Returns StateError::UnknownField for an undeclared key, StateError::MissingValue for an empty slot, or StateError::TypeMismatch when the stored concrete type differs from T.

pub fn take<T>(&mut self, key: &str) -> Result<T, StateError>

where T: Any + Send,

Removes and returns the payload from a declared field.

A successful call moves the original concrete T out of its internal box and leaves the field slot empty. It does not invoke Clone. If T does not match, the original erased value is restored before the error is returned.

Errors

Returns StateError::UnknownField for an undeclared key, StateError::MissingValue for an empty slot, or StateError::TypeMismatch when the stored concrete type differs from T.

pub fn clear(&mut self, key: &str) -> Result<bool, StateError>

Drops the payload stored in one declared field.

Returns true when a payload was present and dropped, or false when the declared slot was already empty.

Errors

Returns StateError::UnknownField when key was not declared by the JSON template.

pub fn clear_all(&mut self)

Drops every payload while retaining the shared layout and time point.

Trait Implementations

impl Clone for SystemState

fn clone(&self) -> Self

Shares the immutable specification and deep-clones populated payloads.

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

Performs copy-assignment from source.

impl Debug for SystemState

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

Formats structural metadata without formatting scientific payloads.