diff --git a/library/std/src/collections/hash/map.rs b/library/std/src/collections/hash/map.rs index 4ec423eb27f31..11ccdd9ea1cc5 100644 --- a/library/std/src/collections/hash/map.rs +++ b/library/std/src/collections/hash/map.rs @@ -896,6 +896,119 @@ where self.base.get_key_value(k) } + /// Attempts to get mutable references to `N` values in the map at once. + /// + /// Returns an array of length `N` with the results of each query. For soundness, at most one + /// mutable reference will be returned to any value. `None` will be returned if any of the + /// keys are duplicates or missing. + /// + /// # Examples + /// + /// ``` + /// #![feature(map_many_mut)] + /// use std::collections::HashMap; + /// + /// let mut libraries = HashMap::new(); + /// libraries.insert("Bodleian Library".to_string(), 1602); + /// libraries.insert("Athenæum".to_string(), 1807); + /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691); + /// libraries.insert("Library of Congress".to_string(), 1800); + /// + /// let got = libraries.get_many_mut([ + /// "Athenæum", + /// "Library of Congress", + /// ]); + /// assert_eq!( + /// got, + /// Some([ + /// &mut 1807, + /// &mut 1800, + /// ]), + /// ); + /// + /// // Missing keys result in None + /// let got = libraries.get_many_mut([ + /// "Athenæum", + /// "New York Public Library", + /// ]); + /// assert_eq!(got, None); + /// + /// // Duplicate keys result in None + /// let got = libraries.get_many_mut([ + /// "Athenæum", + /// "Athenæum", + /// ]); + /// assert_eq!(got, None); + /// ``` + #[inline] + #[unstable(feature = "map_many_mut", issue = "97601")] + pub fn get_many_mut(&mut self, ks: [&Q; N]) -> Option<[&'_ mut V; N]> + where + K: Borrow, + Q: Hash + Eq, + { + self.base.get_many_mut(ks) + } + + /// Attempts to get mutable references to `N` values in the map at once, without validating that + /// the values are unique. + /// + /// Returns an array of length `N` with the results of each query. `None` will be returned if + /// any of the keys are missing. + /// + /// For a safe alternative see [`get_many_mut`](Self::get_many_mut). + /// + /// # Safety + /// + /// Calling this method with overlapping keys is *[undefined behavior]* even if the resulting + /// references are not used. + /// + /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html + /// + /// # Examples + /// + /// ``` + /// #![feature(map_many_mut)] + /// use std::collections::HashMap; + /// + /// let mut libraries = HashMap::new(); + /// libraries.insert("Bodleian Library".to_string(), 1602); + /// libraries.insert("Athenæum".to_string(), 1807); + /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691); + /// libraries.insert("Library of Congress".to_string(), 1800); + /// + /// let got = libraries.get_many_mut([ + /// "Athenæum", + /// "Library of Congress", + /// ]); + /// assert_eq!( + /// got, + /// Some([ + /// &mut 1807, + /// &mut 1800, + /// ]), + /// ); + /// + /// // Missing keys result in None + /// let got = libraries.get_many_mut([ + /// "Athenæum", + /// "New York Public Library", + /// ]); + /// assert_eq!(got, None); + /// ``` + #[inline] + #[unstable(feature = "map_many_mut", issue = "97601")] + pub unsafe fn get_many_unchecked_mut( + &mut self, + ks: [&Q; N], + ) -> Option<[&'_ mut V; N]> + where + K: Borrow, + Q: Hash + Eq, + { + self.base.get_many_unchecked_mut(ks) + } + /// 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