Intern all strings and phrases in the search logic

milli/src/search/new/interner.rs

@@ -0,0 +1,78 @@
+use fxhash::FxHashMap;
+use std::hash::Hash;
+use std::marker::PhantomData;
+
+pub struct Interned<T> {
+    idx: u32,
+    _phantom: PhantomData<T>,
+}
+
+impl<T> Interned<T> {
+    fn new(idx: u32) -> Self {
+        Self { idx, _phantom: PhantomData }
+    }
+}
+
+pub struct Interner<T> {
+    stable_store: Vec<T>,
+    lookup: FxHashMap<T, Interned<T>>,
+}
+impl<T> Default for Interner<T> {
+    fn default() -> Self {
+        Self { stable_store: Default::default(), lookup: Default::default() }
+    }
+}
+
+impl<T> Interner<T>
+where
+    T: Clone + Eq + Hash,
+{
+    pub fn insert(&mut self, s: T) -> Interned<T> {
+        if let Some(interned) = self.lookup.get(&s) {
+            *interned
+        } else {
+            self.stable_store.push(s.clone());
+            let interned = Interned::new(self.stable_store.len() as u32 - 1);
+            self.lookup.insert(s, interned);
+            interned
+        }
+    }
+    pub fn get(&self, interned: Interned<T>) -> &T {
+        &self.stable_store[interned.idx as usize]
+    }
+}
+
+// Interned<T> boilerplate implementations
+
+impl<T> Hash for Interned<T> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.idx.hash(state);
+    }
+}
+
+impl<T: Ord> Ord for Interned<T> {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.idx.cmp(&other.idx)
+    }
+}
+
+impl<T> PartialOrd for Interned<T> {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        self.idx.partial_cmp(&other.idx)
+    }
+}
+
+impl<T> Eq for Interned<T> {}
+
+impl<T> PartialEq for Interned<T> {
+    fn eq(&self, other: &Self) -> bool {
+        self.idx == other.idx
+    }
+}
+impl<T> Clone for Interned<T> {
+    fn clone(&self) -> Self {
+        Self { idx: self.idx, _phantom: PhantomData }
+    }
+}
+
+impl<T> Copy for Interned<T> {}