Struct RingSet

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

A ring buffer that also keeps track of the keys it contains to avoid duplicates.

This serves as a backend for the preview cache. Basic idea:

• When a new key is pushed, if it’s already in the buffer, do nothing.
• If the buffer is full, remove the oldest key and push the new key.

Example

use television_utils::cache::RingSet;

let mut ring_set = RingSet::with_capacity(3);
// push 3 values into the ringset
assert_eq!(ring_set.push(1), None);
assert_eq!(ring_set.push(2), None);
assert_eq!(ring_set.push(3), None);

// check that the values are in the buffer
assert!(ring_set.contains(&1));
assert!(ring_set.contains(&2));
assert!(ring_set.contains(&3));

// push an existing value (should do nothing)
assert_eq!(ring_set.push(1), None);

// entries should still be there
assert!(ring_set.contains(&1));
assert!(ring_set.contains(&2));
assert!(ring_set.contains(&3));

// push a new value, should remove the oldest value (1)
assert_eq!(ring_set.push(4), Some(1));

// 1 is no longer there but 2 and 3 remain
assert!(!ring_set.contains(&1));
assert!(ring_set.contains(&2));
assert!(ring_set.contains(&3));
assert!(ring_set.contains(&4));

Implementations

impl<T> RingSet<T>

where T: Eq + Hash + Clone + Debug,

pub fn with_capacity(capacity: usize) -> Self

Create a new RingSet with the given capacity.

pub fn push(&mut self, item: T) -> Option<T>

Push a new item to the back of the buffer, removing the oldest item if the buffer is full. Returns the item that was removed, if any. If the item is already in the buffer, do nothing and return None.

pub fn contains(&self, key: &T) -> bool

Trait Implementations

impl<T: Debug> Debug for RingSet<T>

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

Formats the value using the given formatter.