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use std::mem::MaybeUninit;
use std::ops::{Deref, DerefMut};
#[derive(Debug)]
pub struct ArrayVec<Item, const CAPACITY: usize>
{
items: [MaybeUninit<Item>; CAPACITY],
len: usize,
}
impl<Item, const CAPACITY: usize> ArrayVec<Item, CAPACITY>
{
#[inline]
#[must_use]
pub fn len(&self) -> usize
{
self.len
}
#[inline]
#[must_use]
pub fn is_empty(&self) -> bool
{
self.len == 0
}
pub fn push(&mut self, item: Item)
{
assert!(self.len < CAPACITY);
self.items[self.len].write(item);
self.len += 1;
}
pub fn insert(&mut self, index: usize, item: Item)
{
assert!(index <= self.len);
assert!(self.len < CAPACITY);
if index == self.len {
self.push(item);
return;
}
unsafe {
std::ptr::copy(
&self.items[index],
&mut self.items[index + 1],
self.len - index,
);
}
self.items[index].write(item);
self.len += 1;
}
}
impl<Item, const CAPACITY: usize> Extend<Item> for ArrayVec<Item, CAPACITY>
{
fn extend<IntoIter: IntoIterator<Item = Item>>(&mut self, iter: IntoIter)
{
for item in iter {
self.push(item);
}
}
}
impl<Item, const CAPACITY: usize> AsRef<[Item]> for ArrayVec<Item, CAPACITY>
{
fn as_ref(&self) -> &[Item]
{
let ptr = &raw const self.items[..self.len];
unsafe { &*(ptr as *const [Item]) }
}
}
impl<Item, const CAPACITY: usize> AsMut<[Item]> for ArrayVec<Item, CAPACITY>
{
fn as_mut(&mut self) -> &mut [Item]
{
let ptr = &raw mut self.items[..self.len];
unsafe { &mut *(ptr as *mut [Item]) }
}
}
impl<Item, const CAPACITY: usize> Deref for ArrayVec<Item, CAPACITY>
{
type Target = [Item];
fn deref(&self) -> &Self::Target
{
self.as_ref()
}
}
impl<Item, const CAPACITY: usize> DerefMut for ArrayVec<Item, CAPACITY>
{
fn deref_mut(&mut self) -> &mut Self::Target
{
self.as_mut()
}
}
impl<Item, const CAPACITY: usize> Default for ArrayVec<Item, CAPACITY>
{
fn default() -> Self
{
Self {
items: [const { MaybeUninit::uninit() }; CAPACITY],
len: 0,
}
}
}
impl<Item, const CAPACITY: usize> Drop for ArrayVec<Item, CAPACITY>
{
fn drop(&mut self)
{
for item in &mut self.items[..self.len] {
// SAFETY: The items from index 0 to the length index will always be
// initialized and satisfy all the invariants of the Item type.
unsafe {
item.assume_init_drop();
}
}
}
}
|
