pub struct RingBuffer<T> {
data: Vec<T>,
i: usize,
}
impl<T> RingBuffer<T> {
pub fn new(capacity: usize) -> Self {
Self {
data: Vec::with_capacity(capacity),
i: 0,
}
}
pub fn capacity(&self) -> usize {
self.data.capacity()
}
pub fn len(&self) -> usize {
self.data.len()
}
pub fn is_full(&self) -> bool {
self.data.len() == self.data.capacity()
}
pub fn is_empty(&self) -> bool {
self.data.len() == 0
}
pub fn push(&mut self, value: T) {
if self.data.len() == self.data.capacity() {
self.data[self.i] = value;
} else {
self.data.push(value);
}
self.i = (self.i + 1) % self.data.capacity();
}
pub fn iter(&self) -> RingBufferIter<'_, T> {
RingBufferIter {
index: 0,
buffer: self,
}
}
}
impl<T: Default> IntoIterator for RingBuffer<T> {
type Item = T;
type IntoIter = OwnedRingBufferIter<T>;
fn into_iter(self) -> OwnedRingBufferIter<T>
where
T: Default,
{
OwnedRingBufferIter {
index: 0,
buffer: self,
}
}
}
pub struct OwnedRingBufferIter<T: Default> {
buffer: RingBuffer<T>,
index: usize,
}
impl<T: Default> Iterator for OwnedRingBufferIter<T> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
if self.index == self.buffer.len() {
return None;
}
let ii = (self.index + self.buffer.i) % self.buffer.len();
let item = std::mem::take(&mut self.buffer.data[ii]);
self.index += 1;
Some(item)
}
}
pub struct RingBufferIter<'a, T> {
buffer: &'a RingBuffer<T>,
index: usize,
}
impl<'a, T> Iterator for RingBufferIter<'a, T> {
type Item = &'a T;
fn next(&mut self) -> Option<Self::Item> {
if self.index == self.buffer.len() {
return None;
}
let ii = (self.index + self.buffer.i) % self.buffer.len();
let item = &self.buffer.data[ii];
self.index += 1;
Some(item)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_inserts() {
let mut rb = RingBuffer::new(3);
assert_eq!(rb.capacity(), 3);
assert!(!rb.is_full());
assert_eq!(rb.len(), 0);
assert_eq!(rb.iter().copied().count(), 0);
rb.push(1);
assert!(!rb.is_full());
assert_eq!(rb.len(), 1);
assert_eq!(rb.iter().copied().collect::<Vec<i32>>(), vec![1]);
rb.push(2);
assert!(!rb.is_full());
assert_eq!(rb.len(), 2);
assert_eq!(rb.iter().copied().collect::<Vec<i32>>(), vec![1, 2]);
rb.push(3);
assert!(rb.is_full());
assert_eq!(rb.len(), 3);
assert_eq!(rb.iter().copied().collect::<Vec<i32>>(), vec![1, 2, 3]);
rb.push(4);
assert!(rb.is_full());
assert_eq!(rb.len(), 3);
assert_eq!(rb.iter().copied().collect::<Vec<i32>>(), vec![2, 3, 4]);
assert_eq!(rb.into_iter().collect::<Vec<i32>>(), vec![2, 3, 4]);
}
}