diff --git a/src/liballoc/btree/map.rs b/src/liballoc/btree/map.rs index ed9c8c18f0d6d..cada190032aa0 100644 --- a/src/liballoc/btree/map.rs +++ b/src/liballoc/btree/map.rs @@ -576,6 +576,33 @@ impl BTreeMap { } } + /// Returns the key-value pair corresponding to the supplied key. + /// + /// The supplied key may be any borrowed form of the map's key type, but the ordering + /// on the borrowed form *must* match the ordering on the key type. + /// + /// # Examples + /// + /// ``` + /// #![feature(map_get_key_value)] + /// use std::collections::BTreeMap; + /// + /// let mut map = BTreeMap::new(); + /// map.insert(1, "a"); + /// assert_eq!(map.get_key_value(&1), Some((&1, &"a"))); + /// assert_eq!(map.get_key_value(&2), None); + /// ``` + #[unstable(feature = "map_get_key_value", issue = "49347")] + pub fn get_key_value(&self, k: &Q) -> Option<(&K, &V)> + where K: Borrow, + Q: Ord + { + match search::search_tree(self.root.as_ref(), k) { + Found(handle) => Some(handle.into_kv()), + GoDown(_) => None, + } + } + /// Returns `true` if the map contains a value for the specified key. /// /// The key may be any borrowed form of the map's key type, but the ordering diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs index b18b38ec30246..f0bb781411fb4 100644 --- a/src/libstd/collections/hash/map.rs +++ b/src/libstd/collections/hash/map.rs @@ -1184,6 +1184,34 @@ impl HashMap self.search(k).map(|bucket| bucket.into_refs().1) } + /// Returns the key-value pair corresponding to the supplied key. + /// + /// The supplied key may be any borrowed form of the map's key type, but + /// [`Hash`] and [`Eq`] on the borrowed form *must* match those for + /// the key type. + /// + /// [`Eq`]: ../../std/cmp/trait.Eq.html + /// [`Hash`]: ../../std/hash/trait.Hash.html + /// + /// # Examples + /// + /// ``` + /// #![feature(map_get_key_value)] + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert(1, "a"); + /// assert_eq!(map.get_key_value(&1), Some((&1, &"a"))); + /// assert_eq!(map.get_key_value(&2), None); + /// ``` + #[unstable(feature = "map_get_key_value", issue = "49347")] + pub fn get_key_value(&self, k: &Q) -> Option<(&K, &V)> + where K: Borrow, + Q: Hash + Eq + { + self.search(k).map(|bucket| bucket.into_refs()) + } + /// Returns true if the map contains a value for the specified key. /// /// The key may be any borrowed form of the map's key type, but