@@ -896,6 +896,119 @@ where
896896 self . base . get_key_value ( k)
897897 }
898898
899+ /// Attempts to get mutable references to `N` values in the map at once.
900+ ///
901+ /// Returns an array of length `N` with the results of each query. For soundness, at most one
902+ /// mutable reference will be returned to any value. `None` will be returned if any of the
903+ /// keys are duplicates or missing.
904+ ///
905+ /// # Examples
906+ ///
907+ /// ```
908+ /// #![feature(map_many_mut)]
909+ /// use std::collections::HashMap;
910+ ///
911+ /// let mut libraries = HashMap::new();
912+ /// libraries.insert("Bodleian Library".to_string(), 1602);
913+ /// libraries.insert("Athenæum".to_string(), 1807);
914+ /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
915+ /// libraries.insert("Library of Congress".to_string(), 1800);
916+ ///
917+ /// let got = libraries.get_many_mut([
918+ /// "Athenæum",
919+ /// "Library of Congress",
920+ /// ]);
921+ /// assert_eq!(
922+ /// got,
923+ /// Some([
924+ /// &mut 1807,
925+ /// &mut 1800,
926+ /// ]),
927+ /// );
928+ ///
929+ /// // Missing keys result in None
930+ /// let got = libraries.get_many_mut([
931+ /// "Athenæum",
932+ /// "New York Public Library",
933+ /// ]);
934+ /// assert_eq!(got, None);
935+ ///
936+ /// // Duplicate keys result in None
937+ /// let got = libraries.get_many_mut([
938+ /// "Athenæum",
939+ /// "Athenæum",
940+ /// ]);
941+ /// assert_eq!(got, None);
942+ /// ```
943+ #[ inline]
944+ #[ unstable( feature = "map_many_mut" , issue = "97601" ) ]
945+ pub fn get_many_mut < Q : ?Sized , const N : usize > ( & mut self , ks : [ & Q ; N ] ) -> Option < [ & ' _ mut V ; N ] >
946+ where
947+ K : Borrow < Q > ,
948+ Q : Hash + Eq ,
949+ {
950+ self . base . get_many_mut ( ks)
951+ }
952+
953+ /// Attempts to get mutable references to `N` values in the map at once, without validating that
954+ /// the values are unique.
955+ ///
956+ /// Returns an array of length `N` with the results of each query. `None` will be returned if
957+ /// any of the keys are missing.
958+ ///
959+ /// For a safe alternative see [`get_many_mut`](Self::get_many_mut).
960+ ///
961+ /// # Safety
962+ ///
963+ /// Calling this method with overlapping keys is *[undefined behavior]* even if the resulting
964+ /// references are not used.
965+ ///
966+ /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
967+ ///
968+ /// # Examples
969+ ///
970+ /// ```
971+ /// #![feature(map_many_mut)]
972+ /// use std::collections::HashMap;
973+ ///
974+ /// let mut libraries = HashMap::new();
975+ /// libraries.insert("Bodleian Library".to_string(), 1602);
976+ /// libraries.insert("Athenæum".to_string(), 1807);
977+ /// libraries.insert("Herzogin-Anna-Amalia-Bibliothek".to_string(), 1691);
978+ /// libraries.insert("Library of Congress".to_string(), 1800);
979+ ///
980+ /// let got = libraries.get_many_mut([
981+ /// "Athenæum",
982+ /// "Library of Congress",
983+ /// ]);
984+ /// assert_eq!(
985+ /// got,
986+ /// Some([
987+ /// &mut 1807,
988+ /// &mut 1800,
989+ /// ]),
990+ /// );
991+ ///
992+ /// // Missing keys result in None
993+ /// let got = libraries.get_many_mut([
994+ /// "Athenæum",
995+ /// "New York Public Library",
996+ /// ]);
997+ /// assert_eq!(got, None);
998+ /// ```
999+ #[ inline]
1000+ #[ unstable( feature = "map_many_mut" , issue = "97601" ) ]
1001+ pub unsafe fn get_many_unchecked_mut < Q : ?Sized , const N : usize > (
1002+ & mut self ,
1003+ ks : [ & Q ; N ] ,
1004+ ) -> Option < [ & ' _ mut V ; N ] >
1005+ where
1006+ K : Borrow < Q > ,
1007+ Q : Hash + Eq ,
1008+ {
1009+ self . base . get_many_unchecked_mut ( ks)
1010+ }
1011+
8991012 /// Returns `true` if the map contains a value for the specified key.
9001013///
9011014/// The key may be any borrowed form of the map's key type, but
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