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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
| commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
| tree | f435a8308119effd964b339f76abb83a57c29483 /third_party/rust/gpu-alloc/src/slab.rs | |
| parent | Initial commit. (diff) | |
| download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip | |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/gpu-alloc/src/slab.rs')
| -rw-r--r-- | third_party/rust/gpu-alloc/src/slab.rs | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/third_party/rust/gpu-alloc/src/slab.rs b/third_party/rust/gpu-alloc/src/slab.rs new file mode 100644 index 0000000000..de413435fe --- /dev/null +++ b/third_party/rust/gpu-alloc/src/slab.rs @@ -0,0 +1,97 @@ +use {crate::unreachable_unchecked, alloc::vec::Vec, core::mem::replace};
+
+#[derive(Debug)]
+enum Entry<T> {
+ Vacant(usize),
+ Occupied(T),
+}
+#[derive(Debug)]
+pub(crate) struct Slab<T> {
+ next_vacant: usize,
+ entries: Vec<Entry<T>>,
+}
+
+impl<T> Slab<T> {
+ pub fn new() -> Self {
+ Slab {
+ next_vacant: !0,
+ entries: Vec::new(),
+ }
+ }
+
+ /// Inserts value into this linked vec and returns index
+ /// at which value can be accessed in constant time.
+ pub fn insert(&mut self, value: T) -> usize {
+ if self.next_vacant >= self.entries.len() {
+ self.entries.push(Entry::Occupied(value));
+ self.entries.len() - 1
+ } else {
+ match *unsafe { self.entries.get_unchecked(self.next_vacant) } {
+ Entry::Vacant(next_vacant) => {
+ unsafe {
+ *self.entries.get_unchecked_mut(self.next_vacant) = Entry::Occupied(value);
+ }
+ replace(&mut self.next_vacant, next_vacant)
+ }
+ _ => unsafe { unreachable_unchecked() },
+ }
+ }
+ }
+
+ pub fn len(&self) -> usize {
+ self.entries.len()
+ }
+
+ pub unsafe fn get_unchecked(&self, index: usize) -> &T {
+ debug_assert!(index < self.len());
+
+ match self.entries.get_unchecked(index) {
+ Entry::Occupied(value) => value,
+ _ => unreachable_unchecked(),
+ }
+ }
+
+ pub unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T {
+ debug_assert!(index < self.len());
+
+ match self.entries.get_unchecked_mut(index) {
+ Entry::Occupied(value) => value,
+ _ => unreachable_unchecked(),
+ }
+ }
+
+ pub fn get(&self, index: usize) -> &T {
+ match self.entries.get(index) {
+ Some(Entry::Occupied(value)) => value,
+ _ => panic!("Invalid index"),
+ }
+ }
+
+ pub fn get_mut(&mut self, index: usize) -> &mut T {
+ match self.entries.get_mut(index) {
+ Some(Entry::Occupied(value)) => value,
+ _ => panic!("Invalid index"),
+ }
+ }
+
+ pub unsafe fn remove_unchecked(&mut self, index: usize) -> T {
+ let entry = replace(
+ self.entries.get_unchecked_mut(index),
+ Entry::Vacant(self.next_vacant),
+ );
+
+ self.next_vacant = index;
+
+ match entry {
+ Entry::Occupied(value) => value,
+ _ => unreachable_unchecked(),
+ }
+ }
+
+ pub fn remove(&mut self, index: usize) -> T {
+ match self.entries.get_mut(index) {
+ Some(Entry::Occupied(_)) => unsafe { self.remove_unchecked(index) },
+ _ => panic!("Invalid index"),
+ }
+ }
+}
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