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use std::{
fmt::{Debug, Formatter},
marker::PhantomData,
sync::atomic::{AtomicUsize, Ordering},
};
pub struct AtomicIndex<T> {
index: AtomicUsize,
phantom: PhantomData<T>,
}
impl<T> Debug for AtomicIndex<T> {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
write!(f, "AtomicIndex: {}", self.get())
}
}
unsafe impl<T> Send for AtomicIndex<T> {}
unsafe impl<T> Sync for AtomicIndex<T> {}
impl<T> Clone for AtomicIndex<T> {
fn clone(&self) -> Self {
Self {
index: AtomicUsize::new(self.index.load(Ordering::SeqCst)),
phantom: PhantomData,
}
}
}
impl<T> Default for AtomicIndex<T> {
fn default() -> Self {
Self::unassigned()
}
}
impl<T> AtomicIndex<T> {
pub fn unassigned() -> Self {
Self {
index: AtomicUsize::new(usize::MAX),
phantom: PhantomData,
}
}
fn new(index: usize) -> Self {
Self {
index: AtomicUsize::new(index),
phantom: PhantomData,
}
}
pub fn set(&self, index: usize) {
self.index.store(index, Ordering::SeqCst)
}
pub fn get(&self) -> usize {
self.index.load(Ordering::SeqCst)
}
}
pub struct SparseBuffer<T> {
vec: Vec<Option<T>>,
free: Vec<usize>,
}
impl<T> Default for SparseBuffer<T> {
fn default() -> Self {
Self {
vec: Default::default(),
free: Default::default(),
}
}
}
impl<T: Clone> Clone for SparseBuffer<T> {
fn clone(&self) -> Self {
Self {
vec: self.vec.clone(),
free: self.free.clone(),
}
}
}
impl<T> SparseBuffer<T> {
pub fn with_capacity(capacity: usize) -> Self {
Self {
vec: Vec::with_capacity(capacity),
free: vec![],
}
}
pub fn spawn(&mut self, payload: T) -> AtomicIndex<T> {
match self.free.pop() {
Some(free) => {
let old = self.vec[free].replace(payload);
debug_assert!(old.is_none());
AtomicIndex::new(free)
}
None => {
let index = AtomicIndex::new(self.vec.len());
self.vec.push(Some(payload));
index
}
}
}
pub fn free(&mut self, index: &AtomicIndex<T>) -> Option<T> {
self.free_raw(index.get())
}
pub fn free_raw(&mut self, index: usize) -> Option<T> {
match self.vec.get_mut(index) {
Some(entry) => match entry.take() {
Some(payload) => {
self.free.push(index);
Some(payload)
}
None => None,
},
None => None,
}
}
pub fn len(&self) -> usize {
self.vec.len()
}
pub fn is_empty(&self) -> bool {
self.filled() == 0
}
pub fn filled(&self) -> usize {
self.vec.len() - self.free.len()
}
pub fn is_index_valid(&self, index: &AtomicIndex<T>) -> bool {
self.get(index).is_some()
}
pub fn get(&self, index: &AtomicIndex<T>) -> Option<&T> {
self.get_raw(index.get())
}
pub fn get_mut(&mut self, index: &AtomicIndex<T>) -> Option<&mut T> {
self.get_mut_raw(index.get())
}
pub fn get_raw(&self, index: usize) -> Option<&T> {
self.vec.get(index).and_then(|entry| entry.as_ref())
}
pub fn get_mut_raw(&mut self, index: usize) -> Option<&mut T> {
self.vec.get_mut(index).and_then(|entry| entry.as_mut())
}
pub fn iter(&self) -> impl Iterator<Item = &T> {
self.vec.iter().filter_map(|entry| entry.as_ref())
}
pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut T> {
self.vec.iter_mut().filter_map(|entry| entry.as_mut())
}
pub fn clear(&mut self) {
self.vec.clear();
self.free.clear();
}
}