| //! Server-side handles and storage for per-handle data. |
| |
| use std::collections::{BTreeMap, HashMap}; |
| use std::hash::Hash; |
| use std::num::NonZeroU32; |
| use std::ops::{Index, IndexMut}; |
| use std::sync::atomic::{AtomicUsize, Ordering}; |
| |
| pub(super) type Handle = NonZeroU32; |
| |
| pub(super) struct OwnedStore<T: 'static> { |
| counter: &'static AtomicUsize, |
| data: BTreeMap<Handle, T>, |
| } |
| |
| impl<T> OwnedStore<T> { |
| pub(super) fn new(counter: &'static AtomicUsize) -> Self { |
| // Ensure the handle counter isn't 0, which would panic later, |
| // when `NonZeroU32::new` (aka `Handle::new`) is called in `alloc`. |
| assert_ne!(counter.load(Ordering::SeqCst), 0); |
| |
| OwnedStore { |
| counter, |
| data: BTreeMap::new(), |
| } |
| } |
| } |
| |
| impl<T> OwnedStore<T> { |
| pub(super) fn alloc(&mut self, x: T) -> Handle { |
| let counter = self.counter.fetch_add(1, Ordering::SeqCst); |
| let handle = Handle::new(counter as u32).expect("`proc_macro` handle counter overflowed"); |
| assert!(self.data.insert(handle, x).is_none()); |
| handle |
| } |
| |
| pub(super) fn take(&mut self, h: Handle) -> T { |
| self.data |
| .remove(&h) |
| .expect("use-after-free in `proc_macro` handle") |
| } |
| } |
| |
| impl<T> Index<Handle> for OwnedStore<T> { |
| type Output = T; |
| fn index(&self, h: Handle) -> &T { |
| self.data |
| .get(&h) |
| .expect("use-after-free in `proc_macro` handle") |
| } |
| } |
| |
| impl<T> IndexMut<Handle> for OwnedStore<T> { |
| fn index_mut(&mut self, h: Handle) -> &mut T { |
| self.data |
| .get_mut(&h) |
| .expect("use-after-free in `proc_macro` handle") |
| } |
| } |
| |
| pub(super) struct InternedStore<T: 'static> { |
| owned: OwnedStore<T>, |
| interner: HashMap<T, Handle>, |
| } |
| |
| impl<T: Copy + Eq + Hash> InternedStore<T> { |
| pub(super) fn new(counter: &'static AtomicUsize) -> Self { |
| InternedStore { |
| owned: OwnedStore::new(counter), |
| interner: HashMap::new(), |
| } |
| } |
| |
| pub(super) fn alloc(&mut self, x: T) -> Handle { |
| let owned = &mut self.owned; |
| *self.interner.entry(x).or_insert_with(|| owned.alloc(x)) |
| } |
| |
| pub(super) fn copy(&mut self, h: Handle) -> T { |
| self.owned[h] |
| } |
| } |