Struct PreviousValueTracker 

pub struct PreviousValueTracker<T> { /* private fields */ }

A specialized delay buffer for comparing current vs previous values.

This is optimized for the common pattern:

// Apama:
// from a in averages from p in (from a in averages retain 1 select rstream a)
// where a > p + threshold

// Varpulis:
let mut tracker = PreviousValueTracker::new();
tracker.update(current_avg);
if let Some(prev) = tracker.previous() {
    if current > prev + threshold { ... }
}

Implementations

impl<T: Clone> PreviousValueTracker<T>

pub const fn new() -> Self

Create a new tracker.

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

Update with a new value, shifting current to previous.

pub const fn current(&self) -> Option<&T>

Get the current value.

pub const fn previous(&self) -> Option<&T>

Get the previous value.

pub const fn has_both(&self) -> bool

Check if we have both current and previous values (ready for comparison).

pub const fn get_pair(&self) -> Option<(&T, &T)>

Get both values as a tuple if both are available.

pub fn reset(&mut self)

Reset the tracker.

Trait Implementations

impl<T: Clone> Clone for PreviousValueTracker<T>

fn clone(&self) -> PreviousValueTracker<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for PreviousValueTracker<T>

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

Formats the value using the given formatter.

impl<T: Default> Default for PreviousValueTracker<T>

fn default() -> PreviousValueTracker<T>

Returns the “default value” for a type.