bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-def/src/dyn_map.rs')
-rw-r--r--crates/hir-def/src/dyn_map.rs116
1 files changed, 116 insertions, 0 deletions
diff --git a/crates/hir-def/src/dyn_map.rs b/crates/hir-def/src/dyn_map.rs
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+++ b/crates/hir-def/src/dyn_map.rs
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+//! This module defines a `DynMap` -- a container for heterogeneous maps.
+//!
+//! This means that `DynMap` stores a bunch of hash maps inside, and those maps
+//! can be of different types.
+//!
+//! It is used like this:
+//!
+//! ```
+//! // keys define submaps of a `DynMap`
+//! const STRING_TO_U32: Key<String, u32> = Key::new();
+//! const U32_TO_VEC: Key<u32, Vec<bool>> = Key::new();
+//!
+//! // Note: concrete type, no type params!
+//! let mut map = DynMap::new();
+//!
+//! // To access a specific map, index the `DynMap` by `Key`:
+//! map[STRING_TO_U32].insert("hello".to_string(), 92);
+//! let value = map[U32_TO_VEC].get(92);
+//! assert!(value.is_none());
+//! ```
+//!
+//! This is a work of fiction. Any similarities to Kotlin's `BindingContext` are
+//! a coincidence.
+use std::{
+ hash::Hash,
+ marker::PhantomData,
+ ops::{Index, IndexMut},
+};
+
+use anymap::Map;
+use rustc_hash::FxHashMap;
+
+pub struct Key<K, V, P = (K, V)> {
+ _phantom: PhantomData<(K, V, P)>,
+}
+
+impl<K, V, P> Key<K, V, P> {
+ pub(crate) const fn new() -> Key<K, V, P> {
+ Key { _phantom: PhantomData }
+ }
+}
+
+impl<K, V, P> Copy for Key<K, V, P> {}
+
+impl<K, V, P> Clone for Key<K, V, P> {
+ fn clone(&self) -> Key<K, V, P> {
+ *self
+ }
+}
+
+pub trait Policy {
+ type K;
+ type V;
+
+ fn insert(map: &mut DynMap, key: Self::K, value: Self::V);
+ fn get<'a>(map: &'a DynMap, key: &Self::K) -> Option<&'a Self::V>;
+ fn is_empty(map: &DynMap) -> bool;
+}
+
+impl<K: Hash + Eq + 'static, V: 'static> Policy for (K, V) {
+ type K = K;
+ type V = V;
+ fn insert(map: &mut DynMap, key: K, value: V) {
+ map.map.entry::<FxHashMap<K, V>>().or_insert_with(Default::default).insert(key, value);
+ }
+ fn get<'a>(map: &'a DynMap, key: &K) -> Option<&'a V> {
+ map.map.get::<FxHashMap<K, V>>()?.get(key)
+ }
+ fn is_empty(map: &DynMap) -> bool {
+ map.map.get::<FxHashMap<K, V>>().map_or(true, |it| it.is_empty())
+ }
+}
+
+pub struct DynMap {
+ pub(crate) map: Map,
+}
+
+impl Default for DynMap {
+ fn default() -> Self {
+ DynMap { map: Map::new() }
+ }
+}
+
+#[repr(transparent)]
+pub struct KeyMap<KEY> {
+ map: DynMap,
+ _phantom: PhantomData<KEY>,
+}
+
+impl<P: Policy> KeyMap<Key<P::K, P::V, P>> {
+ pub fn insert(&mut self, key: P::K, value: P::V) {
+ P::insert(&mut self.map, key, value)
+ }
+ pub fn get(&self, key: &P::K) -> Option<&P::V> {
+ P::get(&self.map, key)
+ }
+
+ pub fn is_empty(&self) -> bool {
+ P::is_empty(&self.map)
+ }
+}
+
+impl<P: Policy> Index<Key<P::K, P::V, P>> for DynMap {
+ type Output = KeyMap<Key<P::K, P::V, P>>;
+ fn index(&self, _key: Key<P::K, P::V, P>) -> &Self::Output {
+ // Safe due to `#[repr(transparent)]`.
+ unsafe { std::mem::transmute::<&DynMap, &KeyMap<Key<P::K, P::V, P>>>(self) }
+ }
+}
+
+impl<P: Policy> IndexMut<Key<P::K, P::V, P>> for DynMap {
+ fn index_mut(&mut self, _key: Key<P::K, P::V, P>) -> &mut Self::Output {
+ // Safe due to `#[repr(transparent)]`.
+ unsafe { std::mem::transmute::<&mut DynMap, &mut KeyMap<Key<P::K, P::V, P>>>(self) }
+ }
+}