Impl more methods and traits for la_arena::ArenaMap

1 files changed, 43 insertions, 0 deletions

diff --git a/lib/la-arena/src/map.rs b/lib/la-arena/src/map.rs
index f74ec5d97cb..3034e33a788 100644
--- a/lib/la-arena/src/map.rs
+++ b/lib/la-arena/src/map.rs
@@ -21,6 +21,33 @@ impl<T, V> ArenaMap<Idx<T>, V> {
         Self { v: Vec::with_capacity(capacity), _ty: PhantomData }
     }
 
+    /// Reserves capacity for at least additional more elements to be inserted in the map.
+    pub fn reserve(&mut self, additional: usize) {
+        self.v.reserve(additional);
+    }
+
+    /// Clears the map, removing all elements.
+    pub fn clear(&mut self) {
+        self.v.clear();
+    }
+
+    /// Shrinks the capacity of the map as much as possible.
+    pub fn shrink_to_fit(&mut self) {
+        let min_len = self.v.iter().rposition(|slot| slot.is_some()).map_or(0, |i| i + 1);
+        self.v.truncate(min_len);
+        self.v.shrink_to_fit();
+    }
+
+    /// Returns whether the map contains a value for the specified index.
+    pub fn contains_idx(&self, idx: Idx<T>) -> bool {
+        matches!(self.v.get(Self::to_idx(idx)), Some(Some(_)))
+    }
+
+    /// Removes an index from the map, returning the value at the index if the index was previously in the map.
+    pub fn remove(&mut self, idx: Idx<T>) -> Option<V> {
+        self.v.get_mut(Self::to_idx(idx))?.take()
+    }
+
     /// Inserts a value associated with a given arena index into the map.
     pub fn insert(&mut self, idx: Idx<T>, t: V) {
         let idx = Self::to_idx(idx);
@@ -94,6 +121,22 @@ impl<T, V> Default for ArenaMap<Idx<V>, T> {
     }
 }
 
+impl<T, V> Extend<(Idx<V>, T)> for ArenaMap<Idx<V>, T> {
+    fn extend<I: IntoIterator<Item = (Idx<V>, T)>>(&mut self, iter: I) {
+        iter.into_iter().for_each(move |(k, v)| {
+            self.insert(k, v);
+        });
+    }
+}
+
+impl<T, V> FromIterator<(Idx<V>, T)> for ArenaMap<Idx<V>, T> {
+    fn from_iter<I: IntoIterator<Item = (Idx<V>, T)>>(iter: I) -> Self {
+        let mut this = Self::new();
+        this.extend(iter);
+        this
+    }
+}
+
 /// A view into a single entry in a map, which may either be vacant or occupied.
 ///
 /// This `enum` is constructed from the [`entry`] method on [`ArenaMap`].