Add shrink_to

RELEASES.md

@@ -15,7 +15,9 @@
  `MutableKeys::get_index_mut2` to access the former behavior.
 
  - `IterMut` and `ValuesMut` now implement `Debug`.
-
+
+ - The new `IndexMap::shrink_to` and `IndexSet::shrink_to` methods shrink
+ the capacity with a lower bound.
 
 - 1.8.1
 

src/map.rs

@@ -332,7 +332,14 @@ where
  ///
  /// Computes in **O(n)** time.
  pub fn shrink_to_fit(&mut self) {
- self.core.shrink_to_fit();
+ self.core.shrink_to(0);
+ }
+
+ /// Shrink the capacity of the map with a lower limit.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn shrink_to(&mut self, min_capacity: usize) {
+ self.core.shrink_to(min_capacity);
  }
 
  fn hash<Q: ?Sized + Hash>(&self, key: &Q) -> HashValue {

src/map/core.rs

@@ -201,10 +201,10 @@ impl<K, V> IndexMapCore<K, V> {
  self.entries.reserve_exact(additional);
  }
 
- /// Shrink the capacity of the map as much as possible.
- pub(crate) fn shrink_to_fit(&mut self) {
- self.indices.shrink_to(0, get_hash(&self.entries));
- self.entries.shrink_to_fit();
+ /// Shrink the capacity of the map with a lower bound
+ pub(crate) fn shrink_to(&mut self, min_capacity: usize) {
+ self.indices.shrink_to(min_capacity, get_hash(&self.entries));
+ self.entries.shrink_to(min_capacity);
  }
 
  /// Remove the last key-value pair

src/set.rs

@@ -268,6 +268,13 @@ where
  self.map.shrink_to_fit();
  }
 
+ /// Shrink the capacity of the set with a lower limit.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn shrink_to(&mut self, min_capacity: usize) {
+ self.map.shrink_to(min_capacity);
+ }
+
  /// Insert the value into the set.
  ///
  /// If an equivalent item already exists in the set, it returns