273 lines
8.3 KiB
Rust
273 lines
8.3 KiB
Rust
use core::{num::NonZeroUsize, usize};
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use allocator_api2::{
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alloc::{Allocator, Global},
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boxed::Box,
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vec::Vec,
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};
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use bytemuck::Contiguous;
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const SPARSE_PAGESIZE: usize = (1 << 10) * 4;
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type SparsePage<A> = Option<(Box<[Option<NonZeroUsize>; SPARSE_PAGESIZE], A>, usize)>;
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pub struct SparseSet<T, PackedAlloc = Global, SparseAlloc = Global>
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where
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PackedAlloc: Allocator,
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SparseAlloc: Allocator,
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{
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sparse: Vec<SparsePage<SparseAlloc>, SparseAlloc>,
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dense: Vec<T, PackedAlloc>,
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dense_to_id: Vec<usize, SparseAlloc>,
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}
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impl<T> SparseSet<T> {
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pub const fn new() -> Self {
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Self {
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sparse: Vec::new(),
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dense: Vec::new(),
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dense_to_id: Vec::new(),
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}
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}
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}
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impl<T, PackedAlloc, SparseAlloc> SparseSet<T, PackedAlloc, SparseAlloc>
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where
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PackedAlloc: Allocator,
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SparseAlloc: Allocator + Clone,
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{
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pub fn insert(&mut self, id: usize, value: T) -> Option<T> {
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match self.get_dense_idx(id) {
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Some(idx) => {
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let previous = core::mem::replace(&mut self.dense[idx], value);
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self.dense_to_id[idx] = id;
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Some(previous)
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}
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None => {
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self.increase_page_usage_count(id);
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self.set_dense_idx(id, Some(self.dense.len()));
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self.dense.push(value);
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self.dense_to_id.push(id);
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None
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}
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}
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}
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pub fn get(&self, id: usize) -> Option<&T> {
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self.dense.get(self.get_dense_idx(id)?)
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}
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pub fn get_mut(&mut self, id: usize) -> Option<&mut T> {
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let idx = self.get_dense_idx(id)?;
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self.dense.get_mut(idx)
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}
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fn set_dense_idx(&mut self, id: usize, idx: Option<usize>) {
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let page = id / SPARSE_PAGESIZE;
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let sparse_index = id % SPARSE_PAGESIZE;
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if page >= self.sparse.len() {
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self.sparse.resize(page + 1, None);
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}
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if self.sparse[page].is_none() {
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self.sparse[page] = Some((
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Box::new_in([None; 4096], self.sparse.allocator().clone()),
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1,
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))
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}
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match &mut self.sparse[page] {
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Some(page) => {
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page.0[sparse_index] = idx.map(|i| NonZeroUsize::new(i + 1).unwrap());
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}
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None => unreachable!("wtf, failed to init sparse page 5 lines above??"),
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}
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}
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pub fn get_dense_idx(&self, id: usize) -> Option<usize> {
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let page = id / SPARSE_PAGESIZE;
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let sparse_index = id % SPARSE_PAGESIZE;
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let page = self.sparse.get(page)?.as_ref()?;
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page.0[sparse_index].map(|idx| idx.into_integer() - 1)
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}
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fn reduce_page_usage_count(&mut self, id: usize) {
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let page = id / SPARSE_PAGESIZE;
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let Some(usage) = &mut self.sparse[page] else {
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return;
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};
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usage.1 -= 1;
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let usage = usage.1;
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if usage == 0 {
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self.sparse[page] = None;
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}
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}
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fn increase_page_usage_count(&mut self, id: usize) {
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let page = id / SPARSE_PAGESIZE;
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if page >= self.sparse.len() {
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return;
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}
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let Some(usage) = &mut self.sparse[page] else {
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return;
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};
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usage.1 += 1;
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}
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pub fn remove(&mut self, id: usize) -> Option<T> {
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let index = self.get_dense_idx(id)?;
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if self.dense.is_empty() {
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return None;
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}
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self.set_dense_idx(*self.dense_to_id.last().unwrap(), Some(index));
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self.set_dense_idx(id, None);
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self.reduce_page_usage_count(id);
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let previous = self.dense.swap_remove(index);
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self.dense_to_id.swap_remove(index);
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Some(previous)
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}
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pub fn is_empty(&self) -> bool {
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self.len() == 0
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}
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pub fn len(&self) -> usize {
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self.dense.len()
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}
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pub fn contains(&self, id: usize) -> bool {
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self.get_dense_idx(id).is_some()
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}
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pub fn keys(&self) -> &[usize] {
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&self.dense_to_id
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}
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pub fn values(&self) -> &[T] {
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&self.dense
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}
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pub fn new_in(packed_alloc: PackedAlloc, sparse_alloc: SparseAlloc) -> Self {
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Self {
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dense: Vec::new_in(packed_alloc),
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sparse: Vec::new_in(sparse_alloc.clone()),
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dense_to_id: Vec::new_in(sparse_alloc),
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}
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}
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}
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impl<T, PackedAlloc> SparseSet<T, PackedAlloc>
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where
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PackedAlloc: Allocator,
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{
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pub const fn new_in_packed(packed_alloc: PackedAlloc) -> Self {
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Self {
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sparse: Vec::new(),
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dense: Vec::new_in(packed_alloc),
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dense_to_id: Vec::new(),
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn insert() {
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let mut sparse_set = SparseSet::<u32>::new();
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sparse_set.insert(10, 1);
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assert_eq!(sparse_set.keys(), &[10]);
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assert_eq!(sparse_set.values(), &[1]);
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assert_eq!(
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sparse_set.sparse[0].as_ref().unwrap().0[10].unwrap(),
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NonZeroUsize::new(1).unwrap()
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);
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assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 1);
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assert_eq!(sparse_set.insert(10, 2).unwrap(), 1);
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assert_eq!(sparse_set.values(), &[2]);
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assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 1);
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sparse_set.insert(11, 4);
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assert_eq!(sparse_set.keys(), &[10, 11]);
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assert_eq!(sparse_set.values(), &[2, 4]);
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assert_eq!(
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sparse_set.sparse[0].as_ref().unwrap().0[11].unwrap(),
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NonZeroUsize::new(2).unwrap()
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);
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assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 2);
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sparse_set.insert(5000, 3);
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assert_eq!(sparse_set.keys(), &[10, 11, 5000]);
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assert_eq!(sparse_set.values(), &[2, 4, 3]);
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assert_eq!(
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sparse_set.sparse[5000 / SPARSE_PAGESIZE]
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.as_ref()
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.unwrap()
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.0[5000 % SPARSE_PAGESIZE]
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.unwrap(),
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NonZeroUsize::new(3).unwrap()
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);
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assert_eq!(
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sparse_set.sparse[5000 / SPARSE_PAGESIZE]
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.as_ref()
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.unwrap()
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.1,
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1
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);
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assert_eq!(*sparse_set.get(10).unwrap(), 2);
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assert_eq!(*sparse_set.get(11).unwrap(), 4);
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assert_eq!(*sparse_set.get(5000).unwrap(), 3);
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}
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#[test]
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fn remove() {
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let mut sparse_set = SparseSet::<u32>::new();
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sparse_set.insert(10, 1);
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sparse_set.insert(11, 2);
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sparse_set.insert(12, 2);
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sparse_set.insert(SPARSE_PAGESIZE, 1);
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sparse_set.insert(SPARSE_PAGESIZE + 1, 2);
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sparse_set.insert(SPARSE_PAGESIZE + 2, 3);
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assert_eq!(sparse_set.remove(SPARSE_PAGESIZE + 2).unwrap(), 3);
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assert_eq!(sparse_set.sparse[1].as_ref().unwrap().1, 2);
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assert_eq!(sparse_set.keys(), [10, 11, 12, SPARSE_PAGESIZE, SPARSE_PAGESIZE + 1]);
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assert_eq!(sparse_set.values(), [1, 2, 2, 1, 2]);
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assert_eq!(sparse_set.remove(SPARSE_PAGESIZE + 1).unwrap(), 2);
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assert_eq!(sparse_set.sparse[1].as_ref().unwrap().1, 1);
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assert_eq!(sparse_set.keys(), [10, 11, 12, SPARSE_PAGESIZE]);
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assert_eq!(sparse_set.values(), [1, 2, 2, 1]);
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assert_eq!(sparse_set.remove(SPARSE_PAGESIZE).unwrap(), 1);
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assert!(sparse_set.sparse[1].is_none());
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assert_eq!(sparse_set.keys(), [10, 11, 12]);
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assert_eq!(sparse_set.values(), [1, 2, 2]);
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sparse_set.insert(SPARSE_PAGESIZE, 1);
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sparse_set.insert(SPARSE_PAGESIZE + 1, 2);
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sparse_set.insert(SPARSE_PAGESIZE + 2, 3);
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assert_eq!(sparse_set.remove(10).unwrap(), 1);
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assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 2);
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// swap-remove
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assert_eq!(sparse_set.keys(), [SPARSE_PAGESIZE + 2, 11, 12, SPARSE_PAGESIZE, SPARSE_PAGESIZE + 1]);
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assert_eq!(sparse_set.values(), [3, 2, 2, 1, 2]);
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assert_eq!(sparse_set.remove(11).unwrap(), 2);
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assert_eq!(sparse_set.sparse[0].as_ref().unwrap().1, 1);
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assert_eq!(sparse_set.keys(), [SPARSE_PAGESIZE + 2, SPARSE_PAGESIZE + 1, 12, SPARSE_PAGESIZE]);
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assert_eq!(sparse_set.values(), [3, 2, 2, 1]);
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assert_eq!(sparse_set.remove(12).unwrap(), 2);
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assert!(sparse_set.sparse[0].is_none());
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assert_eq!(sparse_set.keys(), [SPARSE_PAGESIZE + 2, SPARSE_PAGESIZE + 1, SPARSE_PAGESIZE]);
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assert_eq!(sparse_set.values(), [3, 2, 1]);
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}
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}
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