+ /// 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()

+ }

+

+ ///

+ /// If the map did not have this index present, None is returned.

+ /// Otherwise, the value is updated, and the old value is returned.

+ pub fn insert(&mut self, idx: Idx<T>, t: V) -> Option<V> {

+ self.v[idx].replace(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

+ }

+}

+