@@ -21,6 +21,7 @@ use core::prelude::*;
2121
2222use self :: StackOp :: * ;
2323use super :: node:: * ;
24+ use core:: borrow:: BorrowFrom ;
2425use std:: hash:: { Writer , Hash } ;
2526use core:: default:: Default ;
2627use core:: { iter, fmt, mem} ;
@@ -56,7 +57,7 @@ use ring_buf::RingBuf;
5657/// and possibly other factors. Using linear search, searching for a random element is expected
5758/// to take O(B log<sub>B</sub>n) comparisons, which is generally worse than a BST. In practice,
5859/// however, performance is excellent. `BTreeMap` is able to readily outperform `TreeMap` under
59- /// many workloads, and is competetive where it doesn't. BTreeMap also generally *scales* better
60+ /// many workloads, and is competitive where it doesn't. BTreeMap also generally *scales* better
6061/// than TreeMap, making it more appropriate for large datasets.
6162///
6263/// However, `TreeMap` may still be more appropriate to use in many contexts. If elements are very
@@ -184,6 +185,9 @@ impl<K: Ord, V> BTreeMap<K, V> {
184185
185186 /// Returns a reference to the value corresponding to the key.
186187///
188+ /// The key may be any borrowed form of the map's key type, but the ordering
189+ /// on the borrowed form *must* match the ordering on the key type.
190+ ///
187191/// # Example
188192///
189193/// ```
@@ -195,7 +199,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
195199/// assert_eq!(map.get(&2), None);
196200/// ```
197201#[ unstable = "matches collection reform specification, waiting for dust to settle" ]
198- pub fn get ( & self , key : & K ) -> Option < & V > {
202+ pub fn get < Sized ? Q > ( & self , key : & Q ) -> Option < & V > where Q : BorrowFrom < K > + Ord {
199203 let mut cur_node = & self . root ;
200204 loop {
201205 match cur_node. search ( key) {
@@ -213,6 +217,9 @@ impl<K: Ord, V> BTreeMap<K, V> {
213217
214218 /// Returns true if the map contains a value for the specified key.
215219///
220+ /// The key may be any borrowed form of the map's key type, but the ordering
221+ /// on the borrowed form *must* match the ordering on the key type.
222+ ///
216223/// # Example
217224///
218225/// ```
@@ -224,7 +231,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
224231/// assert_eq!(map.contains_key(&2), false);
225232/// ```
226233#[ unstable = "matches collection reform specification, waiting for dust to settle" ]
227- pub fn contains_key ( & self , key : & K ) -> bool {
234+ pub fn contains_key < Sized ? Q > ( & self , key : & Q ) -> bool where Q : BorrowFrom < K > + Ord {
228235 self . get ( key) . is_some ( )
229236 }
230237
@@ -236,6 +243,9 @@ impl<K: Ord, V> BTreeMap<K, V> {
236243
237244 /// Returns a mutable reference to the value corresponding to the key.
238245///
246+ /// The key may be any borrowed form of the map's key type, but the ordering
247+ /// on the borrowed form *must* match the ordering on the key type.
248+ ///
239249/// # Example
240250///
241251/// ```
@@ -251,7 +261,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
251261/// ```
252262// See `get` for implementation notes, this is basically a copy-paste with mut's added
253263 #[ unstable = "matches collection reform specification, waiting for dust to settle" ]
254- pub fn get_mut ( & mut self , key : & K ) -> Option < & mut V > {
264+ pub fn get_mut < Sized ? Q > ( & mut self , key : & Q ) -> Option < & mut V > where Q : BorrowFrom < K > + Ord {
255265 // temp_node is a Borrowck hack for having a mutable value outlive a loop iteration
256266 let mut temp_node = & mut self . root ;
257267 loop {
@@ -410,6 +420,9 @@ impl<K: Ord, V> BTreeMap<K, V> {
410420 /// Removes a key from the map, returning the value at the key if the key
411421/// was previously in the map.
412422///
423+ /// The key may be any borrowed form of the map's key type, but the ordering
424+ /// on the borrowed form *must* match the ordering on the key type.
425+ ///
413426/// # Example
414427///
415428/// ```
@@ -421,7 +434,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
421434/// assert_eq!(map.remove(&1), None);
422435/// ```
423436#[ unstable = "matches collection reform specification, waiting for dust to settle" ]
424- pub fn remove ( & mut self , key : & K ) -> Option < V > {
437+ pub fn remove < Sized ? Q > ( & mut self , key : & Q ) -> Option < V > where Q : BorrowFrom < K > + Ord {
425438 // See `swap` for a more thorough description of the stuff going on in here
426439 let mut stack = stack:: PartialSearchStack :: new ( self ) ;
427440 loop {
@@ -790,14 +803,18 @@ impl<K: Show, V: Show> Show for BTreeMap<K, V> {
790803 }
791804}
792805
793- impl < K : Ord , V > Index < K , V > for BTreeMap < K , V > {
794- fn index ( & self , key : & K ) -> & V {
806+ impl < K : Ord , Sized ? Q , V > Index < Q , V > for BTreeMap < K , V >
807+ where Q : BorrowFrom < K > + Ord
808+ {
809+ fn index ( & self , key : & Q ) -> & V {
795810 self . get ( key) . expect ( "no entry found for key" )
796811 }
797812}
798813
799- impl < K : Ord , V > IndexMut < K , V > for BTreeMap < K , V > {
800- fn index_mut ( & mut self , key : & K ) -> & mut V {
814+ impl < K : Ord , Sized ? Q , V > IndexMut < Q , V > for BTreeMap < K , V >
815+ where Q : BorrowFrom < K > + Ord
816+ {
817+ fn index_mut ( & mut self , key : & Q ) -> & mut V {
801818 self . get_mut ( key) . expect ( "no entry found for key" )
802819 }
803820}
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