diff options
| -rw-r--r-- | src/libstd/collections/hash/map.rs | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs index 96af2272578..026b863b963 100644 --- a/src/libstd/collections/hash/map.rs +++ b/src/libstd/collections/hash/map.rs @@ -2191,6 +2191,36 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { fn take_key(&mut self) -> Option<K> { self.key.take() } + + /// Replaces the entry, returning the old key and value. + /// + /// # Examples + /// + /// ``` + /// #![feature(map_entry_replace)] + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<String, u32> = HashMap::new(); + /// map.insert("poneyland".to_string(), 15); + /// + /// if let Entry::Occupied(entry) = map.entry("poneyland".to_string()) { + /// let (old_key, old_value): (String, u32) = entry.replace(16); + /// assert_eq!(old_key, "poneyland"); + /// assert_eq!(old_value, 15); + /// } + /// + /// assert_eq!(map.get("poneyland"), Some(&16)); + /// ``` + #[unstable(feature = "map_entry_replace", issue = "44286")] + pub fn replace(mut self, value: V) -> (K, V) { + let (old_key, old_value) = self.elem.read_mut(); + + let old_key = mem::replace(old_key, self.key.unwrap()); + let old_value = mem::replace(old_value, value); + + (old_key, old_value) + } } impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> { |