use std::{
collections::{BTreeMap, HashMap},
sync::Arc,
};
#[derive(Debug, Clone, PartialEq)]
pub struct RollingSet<T: std::hash::Hash + std::cmp::Eq> {
value_identifyer: usize,
capacity: usize,
time_to_value: BTreeMap<usize, Arc<T>>,
value_to_time: HashMap<Arc<T>, usize>,
}
impl<T> RollingSet<T>
where
T: Eq + std::hash::Hash + Clone,
{
pub fn new(capacity: usize) -> Self {
Self {
capacity,
value_identifyer: 0,
time_to_value: BTreeMap::new(),
value_to_time: HashMap::new(),
}
}
pub fn with_capacity(capacity: usize) -> Self {
Self {
capacity,
value_identifyer: 0,
time_to_value: BTreeMap::new(),
value_to_time: HashMap::with_capacity(capacity),
}
}
pub fn insert(&mut self, element: T) {
self.value_identifyer += 1;
let v = Arc::new(element);
self.time_to_value.insert(self.value_identifyer, v.clone());
self.value_to_time.insert(v, self.value_identifyer);
if self.len() > self.capacity {
self.pop();
}
}
pub fn pop(&mut self) -> Option<T> {
let first = self.time_to_value.first_key_value()?.0.clone();
let value = self.time_to_value.get(&first)?.clone();
self.value_to_time.remove(&value);
self.time_to_value.remove(&first);
if !self.is_empty() {
self.value_identifyer = 0;
}
Some((*value).clone())
}
pub fn is_empty(&self) -> bool {
self.len() == 0
}
pub fn is_full(&self) -> bool {
self.len() == self.capacity
}
pub fn set_capacity(&mut self, new: usize) -> usize {
self.capacity = new;
self.capacity
}
pub fn capacity(&self) -> usize {
self.capacity
}
pub fn remove(&mut self, element: &T) -> bool {
let i = match self.value_to_time.get(element) {
Some(i) => i,
None => return false,
};
self.time_to_value.remove(i);
self.value_to_time.remove(element);
true
}
pub fn contains(&self, element: &T) -> bool {
self.value_to_time.contains_key(element)
}
pub fn len(&self) -> usize {
self.value_to_time.len()
}
pub fn clear(&mut self) {
self.value_identifyer = 0;
self.time_to_value.clear();
self.value_to_time.clear();
}
}
#[cfg(test)]
mod tests {
use crate::RollingSet;
#[test]
fn create() {
let mut set = RollingSet::new(100);
set.insert("one");
set.insert("two");
set.insert("three");
assert!(set.contains(&"one"));
assert!(set.contains(&"two"));
assert!(set.contains(&"three"));
assert!(!set.contains(&"four"));
}
#[test]
fn roll() {
let mut set = RollingSet::new(3);
set.insert("one");
set.insert("two");
set.insert("three");
set.insert("four");
assert_eq!(set.len(), 3);
assert!(!set.contains(&"one"));
assert!(set.contains(&"two"));
assert!(set.contains(&"three"));
assert!(set.contains(&"four"));
}
#[test]
fn remove() {
let mut set = RollingSet::new(3);
set.insert("one");
set.insert("two");
set.insert("three");
set.insert("four");
assert!(set.contains(&"two"));
assert!(set.contains(&"three"));
assert!(set.contains(&"four"));
set.remove(&"two");
assert_eq!(set.len(), 2);
assert!(!set.contains(&"two"));
assert!(set.contains(&"three"));
assert!(set.contains(&"four"));
}
#[test]
fn len() {
let mut set = RollingSet::new(3);
set.insert("one");
set.insert("two");
set.insert("three");
assert_eq!(set.len(), 3);
set.insert("four");
assert_eq!(set.len(), 3);
assert!(set.contains(&"two"));
assert!(set.contains(&"three"));
assert!(set.contains(&"four"));
set.remove(&"two");
assert_eq!(set.len(), 2);
assert!(!set.contains(&"two"));
assert!(set.contains(&"three"));
assert!(set.contains(&"four"));
}
#[test]
fn pop() {
let mut set = RollingSet::new(3);
set.insert("one");
set.insert("two");
set.insert("three");
assert_eq!(set.len(), 3);
let value = set.pop();
assert_eq!(value, Some("one"));
assert_eq!(set.len(), 2);
let value = set.pop();
assert_eq!(value, Some("two"));
assert_eq!(set.len(), 1);
let value = set.pop();
assert_eq!(value, Some("three"));
assert_eq!(set.len(), 0);
set.insert("one");
set.insert("two");
set.insert("three");
set.insert("four");
assert_eq!(set.len(), 3);
let value = set.pop();
assert_eq!(value, Some("two"));
assert_eq!(set.len(), 2);
let value = set.pop();
assert_eq!(value, Some("three"));
assert_eq!(set.len(), 1);
let value = set.pop();
assert_eq!(value, Some("four"));
assert_eq!(set.len(), 0);
}
#[test]
fn iter() {
let mut set = RollingSet::new(3);
set.insert("one");
set.insert("two");
set.insert("three");
}
}