Method retain

cranelift/bforest/src/map.rs:181–200

Retains only the elements specified by the predicate. Remove all key-value pairs where the predicate returns false. The predicate is allowed to update the values stored in the map.

(&mut self, forest: &mut MapForest<K, V>, mut predicate: F)

    ///
    /// The predicate is allowed to update the values stored in the map.
    pub fn retain<F>(&mut self, forest: &mut MapForest<K, V>, mut predicate: F)
    where
        F: FnMut(K, &mut V) -> bool,
    {
        let mut path = Path::default();
        if let Some(root) = self.root.expand() {
            path.first(root, &forest.nodes);
        }
        while let Some((node, entry)) = path.leaf_pos() {
            let keep = {
                let (ks, vs) = forest.nodes[node].unwrap_leaf_mut();
                predicate(ks[entry], &mut vs[entry])
            };
            if keep {
                path.next(&forest.nodes);
            } else {
                self.root = path.remove(&mut forest.nodes).into();
            }
        }
    }

    /// Create an immutable cursor for navigating this map.
    ///