| //! Trait for extending `HashMap` with `get_or_default`. |
| use std::collections::HashMap; |
| use std::hash::Hash; |
| |
| pub(crate) trait MapWithDefault<K, V: Default> { |
| fn get_or_default(&mut self, k: K) -> &mut V; |
| } |
| |
| impl<K: Eq + Hash, V: Default> MapWithDefault<K, V> for HashMap<K, V> { |
| fn get_or_default(&mut self, k: K) -> &mut V { |
| self.entry(k).or_insert_with(V::default) |
| } |
| } |
| |
| #[test] |
| fn test_default() { |
| let mut hash_map = HashMap::new(); |
| hash_map.insert(42, "hello"); |
| assert_eq!(*hash_map.get_or_default(43), ""); |
| } |
