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use std::collections::VecDeque;
use std::ops::{Index, IndexMut};
#[derive(Debug, Clone)]
pub struct Buffer<T> {
offset: usize,
storage: VecDeque<T>,
}
impl<T> Buffer<T> {
pub fn new() -> Self {
Self {
offset: 0,
storage: VecDeque::new(),
}
}
pub fn push_right(&mut self, elem: T) -> usize {
let index = self.offset + self.storage.len();
self.storage.push_back(elem);
index
}
pub fn left(&self) -> usize {
self.offset
}
pub fn left_elem(&self) -> Option<&T> {
self.storage.front()
}
pub fn pop_left(&mut self) -> Option<T> {
self.offset += 1;
self.storage.pop_front()
}
pub fn clear(&mut self) {
self.storage.clear();
}
pub fn is_empty(&self) -> bool {
self.storage.is_empty()
}
}
impl<T> Index<usize> for Buffer<T> {
type Output = T;
fn index(&self, index: usize) -> &Self::Output {
&self.storage[index.checked_sub(self.offset).unwrap()]
}
}
impl<T> IndexMut<usize> for Buffer<T> {
fn index_mut(&mut self, index: usize) -> &mut Self::Output {
&mut self.storage[index.checked_sub(self.offset).unwrap()]
}
}