X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Fmono_hash_map.rs;h=fb0169920ee28fedc71d6b8882935c8429797cd1;hb=20e31dbdad67080eb83aa3b5330dfe2f116f9900;hp=278bbd9cf2b13d5ead44c7b1de87f615d0542fba;hpb=5958fa6a7049cd003e87d6d8502ae1237262c378;p=rust.git

diff --git a/src/mono_hash_map.rs b/src/mono_hash_map.rs
index 278bbd9cf2b..fb0169920ee 100644
--- a/src/mono_hash_map.rs
+++ b/src/mono_hash_map.rs
@@ -1,14 +1,14 @@
-//! This is a "monotonic HashMap": A HashMap that, when shared, can be pushed to but not
-//! otherwise mutated.  We also Box items in the map. This means we can safely provide
-//! shared references into existing items in the HashMap, because they will not be dropped
+//! This is a "monotonic `FxHashMap`": A `FxHashMap` that, when shared, can be pushed to but not
+//! otherwise mutated. We also box items in the map. This means we can safely provide
+//! shared references into existing items in the `FxHashMap`, because they will not be dropped
 //! (from being removed) or moved (because they are boxed).
 //! The API is is completely tailored to what `memory.rs` needs. It is still in
 //! a separate file to minimize the amount of code that has to care about the unsafety.
 
-use std::collections::hash_map::Entry;
+use std::borrow::Borrow;
 use std::cell::RefCell;
+use std::collections::hash_map::Entry;
 use std::hash::Hash;
-use std::borrow::Borrow;
 
 use rustc_data_structures::fx::FxHashMap;
 
@@ -18,8 +18,16 @@
 pub struct MonoHashMap<K: Hash + Eq, V>(RefCell<FxHashMap<K, Box<V>>>);
 
 impl<K: Hash + Eq, V> MonoHashMap<K, V> {
-    pub fn values<T>(&self, f: impl FnOnce(&mut dyn Iterator<Item=&V>) -> T) -> T {
-        f(&mut self.0.borrow().values().map(|v| &**v))
+    /// This function exists for priroda to be able to iterate over all evaluator memory.
+    ///
+    /// The function is somewhat roundabout with the closure argument because internally the
+    /// `MonoHashMap` uses a `RefCell`. When iterating over the `FxHashMap` inside the `RefCell`,
+    /// we need to keep a borrow to the `FxHashMap` inside the iterator. The borrow is only alive
+    /// as long as the `Ref` returned by `RefCell::borrow()` is alive. So we can't return the
+    /// iterator, as that would drop the `Ref`. We can't return both, as it's not possible in Rust
+    /// to have a struct/tuple with a field that refers to another field.
+    pub fn iter<T>(&self, f: impl FnOnce(&mut dyn Iterator<Item = (&K, &V)>) -> T) -> T {
+        f(&mut self.0.borrow().iter().map(|(k, v)| (k, &**v)))
     }
 }
 
@@ -32,44 +40,38 @@ fn default() -> Self {
 impl<K: Hash + Eq, V> AllocMap<K, V> for MonoHashMap<K, V> {
     #[inline(always)]
     fn contains_key<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> bool
-        where K: Borrow<Q>
+    where
+        K: Borrow<Q>,
     {
         self.0.get_mut().contains_key(k)
     }
 
     #[inline(always)]
-    fn insert(&mut self, k: K, v: V) -> Option<V>
-    {
+    fn insert(&mut self, k: K, v: V) -> Option<V> {
         self.0.get_mut().insert(k, Box::new(v)).map(|x| *x)
     }
 
     #[inline(always)]
     fn remove<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> Option<V>
-        where K: Borrow<Q>
+    where
+        K: Borrow<Q>,
     {
         self.0.get_mut().remove(k).map(|x| *x)
     }
 
     #[inline(always)]
     fn filter_map_collect<T>(&self, mut f: impl FnMut(&K, &V) -> Option<T>) -> Vec<T> {
-        self.0.borrow()
-            .iter()
-            .filter_map(move |(k, v)| f(k, &*v))
-            .collect()
+        self.0.borrow().iter().filter_map(move |(k, v)| f(k, &*v)).collect()
     }
 
-    /// The most interesting method: Providing a shared ref without
+    /// The most interesting method: Providing a shared reference without
     /// holding the `RefCell` open, and inserting new data if the key
     /// is not used yet.
     /// `vacant` is called if the key is not found in the map;
     /// if it returns a reference, that is used directly, if it
     /// returns owned data, that is put into the map and returned.
     #[inline(always)]
-    fn get_or<E>(
-        &self,
-        k: K,
-        vacant: impl FnOnce() -> Result<V, E>
-    ) -> Result<&V, E> {
+    fn get_or<E>(&self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&V, E> {
         let val: *const V = match self.0.borrow_mut().entry(k) {
             Entry::Occupied(entry) => &**entry.get(),
             Entry::Vacant(entry) => &**entry.insert(Box::new(vacant()?)),
@@ -80,12 +82,7 @@ fn get_or<E>(
     }
 
     #[inline(always)]
-    fn get_mut_or<E>(
-        &mut self,
-        k: K,
-        vacant: impl FnOnce() -> Result<V, E>
-    ) -> Result<&mut V, E>
-    {
+    fn get_mut_or<E>(&mut self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&mut V, E> {
         match self.0.get_mut().entry(k) {
             Entry::Occupied(e) => Ok(e.into_mut()),
             Entry::Vacant(e) => {