auto merge of #20163 : bfops/rust/master, r=Gankro

TODOs:
  - ~~Entry is still `<'a, K, V>` instead of `<'a, O, V>`~~
  - ~~BTreeMap is still outstanding~~.
  - ~~Transform appropriate things into `.entry(...).get().or_else(|e| ...)`~~

Things that make me frowny face:
  - I'm not happy about the fact that this `clone`s the key even when it's already owned.
  - With small keys (e.g. `int`s), taking a reference seems wasteful.

r? @gankro
cc: @cgaebel

Author: bors

src/libcollections/bench.rs

@@ -11,7 +11,7 @@
 use prelude::*;
 use std::rand;
 use std::rand::Rng;
-use test::Bencher;
+use test::{Bencher, black_box};
 
 pub fn insert_rand_n<M, I, R>(n: uint,
                               map: &mut M,
@@ -33,7 +33,8 @@ pub fn insert_rand_n<M, I, R>(n: uint,
         let k = rng.gen::<uint>() % n;
         insert(map, k);
         remove(map, k);
-    })
+    });
+    black_box(map);
 }
 
 pub fn insert_seq_n<M, I, R>(n: uint,
@@ -55,7 +56,8 @@ pub fn insert_seq_n<M, I, R>(n: uint,
         insert(map, i);
         remove(map, i);
         i = (i + 2) % n;
-    })
+    });
+    black_box(map);
 }
 
 pub fn find_rand_n<M, T, I, F>(n: uint,
@@ -82,7 +84,7 @@ pub fn find_rand_n<M, T, I, F>(n: uint,
     b.iter(|| {
         let t = find(map, keys[i]);
         i = (i + 1) % n;
-        t
+        black_box(t);
     })
 }
 
@@ -104,6 +106,6 @@ pub fn find_seq_n<M, T, I, F>(n: uint,
     b.iter(|| {
         let x = find(map, i);
         i = (i + 1) % n;
-        x
+        black_box(x);
     })
 }

src/libcollections/btree/map.rs

@@ -19,7 +19,7 @@ pub use self::Entry::*;
 
 use core::prelude::*;
 
-use core::borrow::BorrowFrom;
+use core::borrow::{BorrowFrom, ToOwned};
 use core::cmp::Ordering;
 use core::default::Default;
 use core::fmt::Show;
@@ -128,20 +128,23 @@ pub struct Values<'a, K: 'a, V: 'a> {
     inner: Map<(&'a K, &'a V), &'a V, Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a V>
 }
 
+#[stable]
 /// A view into a single entry in a map, which may either be vacant or occupied.
-pub enum Entry<'a, K:'a, V:'a> {
+pub enum Entry<'a, Sized? Q:'a, K:'a, V:'a> {
     /// A vacant Entry
-    Vacant(VacantEntry<'a, K, V>),
+    Vacant(VacantEntry<'a, Q, K, V>),
     /// An occupied Entry
     Occupied(OccupiedEntry<'a, K, V>),
 }
 
+#[stable]
 /// A vacant Entry.
-pub struct VacantEntry<'a, K:'a, V:'a> {
-    key: K,
+pub struct VacantEntry<'a, Sized? Q:'a, K:'a, V:'a> {
+    key: &'a Q,
     stack: stack::SearchStack<'a, K, V, node::handle::Edge, node::handle::Leaf>,
 }
 
+#[stable]
 /// An occupied Entry.
 pub struct OccupiedEntry<'a, K:'a, V:'a> {
     stack: stack::SearchStack<'a, K, V, node::handle::KV, node::handle::LeafOrInternal>,
@@ -1132,40 +1135,56 @@ impl<'a, K, V> DoubleEndedIterator for Values<'a, K, V> {
 #[stable]
 impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {}
 
+impl<'a, Sized? Q, K: Ord, V> Entry<'a, Q, K, V> {
+    #[unstable = "matches collection reform v2 specification, waiting for dust to settle"]
+    /// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
+    pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, Q, K, V>> {
+        match self {
+            Occupied(entry) => Ok(entry.into_mut()),
+            Vacant(entry) => Err(entry),
+        }
+    }
+}
 
-impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
+impl<'a, Sized? Q: ToOwned<K>, K: Ord, V> VacantEntry<'a, Q, K, V> {
+    #[stable]
     /// Sets the value of the entry with the VacantEntry's key,
     /// and returns a mutable reference to it.
-    pub fn set(self, value: V) -> &'a mut V {
-        self.stack.insert(self.key, value)
+    pub fn insert(self, value: V) -> &'a mut V {
+        self.stack.insert(self.key.to_owned(), value)
     }
 }
 
 impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
+    #[stable]
     /// Gets a reference to the value in the entry.
     pub fn get(&self) -> &V {
         self.stack.peek()
     }
 
+    #[stable]
     /// Gets a mutable reference to the value in the entry.
     pub fn get_mut(&mut self) -> &mut V {
         self.stack.peek_mut()
     }
 
+    #[stable]
     /// Converts the entry into a mutable reference to its value.
     pub fn into_mut(self) -> &'a mut V {
         self.stack.into_top()
     }
 
+    #[stable]
     /// Sets the value of the entry with the OccupiedEntry's key,
     /// and returns the entry's old value.
-    pub fn set(&mut self, mut value: V) -> V {
+    pub fn insert(&mut self, mut value: V) -> V {
         mem::swap(self.stack.peek_mut(), &mut value);
         value
     }
 
+    #[stable]
     /// Takes the value of the entry out of the map, and returns it.
-    pub fn take(self) -> V {
+    pub fn remove(self) -> V {
         self.stack.remove()
     }
 }
@@ -1352,9 +1371,9 @@ impl<K: Ord, V> BTreeMap<K, V> {
     ///
     /// // count the number of occurrences of letters in the vec
     /// for x in vec!["a","b","a","c","a","b"].iter() {
-    ///     match count.entry(*x) {
+    ///     match count.entry(x) {
     ///         Entry::Vacant(view) => {
-    ///             view.set(1);
+    ///             view.insert(1);
     ///         },
     ///         Entry::Occupied(mut view) => {
     ///             let v = view.get_mut();
@@ -1365,12 +1384,16 @@ impl<K: Ord, V> BTreeMap<K, V> {
     ///
     /// assert_eq!(count["a"], 3u);
     /// ```
-    pub fn entry<'a>(&'a mut self, mut key: K) -> Entry<'a, K, V> {
+    /// The key must have the same ordering before or after `.to_owned()` is called.
+    #[stable]
+    pub fn entry<'a, Sized? Q>(&'a mut self, mut key: &'a Q) -> Entry<'a, Q, K, V>
+        where Q: Ord + ToOwned<K>
+    {
         // same basic logic of `swap` and `pop`, blended together
         let mut stack = stack::PartialSearchStack::new(self);
         loop {
             let result = stack.with(move |pusher, node| {
-                return match Node::search(node, &key) {
+                return match Node::search(node, key) {
                     Found(handle) => {
                         // Perfect match
                         Finished(Occupied(OccupiedEntry {
@@ -1413,6 +1436,7 @@ impl<K: Ord, V> BTreeMap<K, V> {
 #[cfg(test)]
 mod test {
     use prelude::*;
+    use std::borrow::{ToOwned, BorrowFrom};
 
     use super::{BTreeMap, Occupied, Vacant};
 
@@ -1562,19 +1586,19 @@ mod test {
         let mut map: BTreeMap<int, int> = xs.iter().map(|&x| x).collect();
 
         // Existing key (insert)
-        match map.entry(1) {
+        match map.entry(&1) {
             Vacant(_) => unreachable!(),
             Occupied(mut view) => {
                 assert_eq!(view.get(), &10);
-                assert_eq!(view.set(100), 10);
+                assert_eq!(view.insert(100), 10);
             }
         }
         assert_eq!(map.get(&1).unwrap(), &100);
         assert_eq!(map.len(), 6);
 
 
         // Existing key (update)
-        match map.entry(2) {
+        match map.entry(&2) {
             Vacant(_) => unreachable!(),
             Occupied(mut view) => {
                 let v = view.get_mut();
@@ -1585,21 +1609,21 @@ mod test {
         assert_eq!(map.len(), 6);
 
         // Existing key (take)
-        match map.entry(3) {
+        match map.entry(&3) {
             Vacant(_) => unreachable!(),
             Occupied(view) => {
-                assert_eq!(view.take(), 30);
+                assert_eq!(view.remove(), 30);
             }
         }
         assert_eq!(map.get(&3), None);
         assert_eq!(map.len(), 5);
 
 
         // Inexistent key (insert)
-        match map.entry(10) {
+        match map.entry(&10) {
             Occupied(_) => unreachable!(),
             Vacant(view) => {
-                assert_eq!(*view.set(1000), 1000);
+                assert_eq!(*view.insert(1000), 1000);
             }
         }
         assert_eq!(map.get(&10).unwrap(), &1000);

src/librustc/lint/builtin.rs

@@ -1329,8 +1329,8 @@ impl UnusedMut {
                 let ident = path1.node;
                 if let ast::BindByValue(ast::MutMutable) = mode {
                     if !token::get_ident(ident).get().starts_with("_") {
-                        match mutables.entry(ident.name.uint()) {
-                            Vacant(entry) => { entry.set(vec![id]); },
+                        match mutables.entry(&ident.name.uint()) {
+                            Vacant(entry) => { entry.insert(vec![id]); },
                             Occupied(mut entry) => { entry.get_mut().push(id); },
                         }
                     }

src/librustc/metadata/creader.rs

@@ -87,8 +87,8 @@ fn dump_crates(cstore: &CStore) {
 fn warn_if_multiple_versions(diag: &SpanHandler, cstore: &CStore) {
     let mut map = FnvHashMap::new();
     cstore.iter_crate_data(|cnum, data| {
-        match map.entry(data.name()) {
-            Vacant(entry) => { entry.set(vec![cnum]); },
+        match map.entry(&data.name()) {
+            Vacant(entry) => { entry.insert(vec![cnum]); },
             Occupied(mut entry) => { entry.get_mut().push(cnum); },
         }
     });

src/librustc/metadata/loader.rs

@@ -228,7 +228,6 @@ use util::fs;
 
 use std::c_str::ToCStr;
 use std::cmp;
-use std::collections::hash_map::Entry::{Occupied, Vacant};
 use std::collections::{HashMap, HashSet};
 use std::io::fs::PathExtensions;
 use std::io;
@@ -400,10 +399,9 @@ impl<'a> Context<'a> {
             };
             info!("lib candidate: {}", path.display());
 
-            let slot = match candidates.entry(hash.to_string()) {
-                Occupied(entry) => entry.into_mut(),
-                Vacant(entry) => entry.set((HashSet::new(), HashSet::new())),
-            };
+            let hash_str = hash.to_string();
+            let slot = candidates.entry(&hash_str).get().unwrap_or_else(
+                |vacant_entry| vacant_entry.insert((HashSet::new(), HashSet::new())));
             let (ref mut rlibs, ref mut dylibs) = *slot;
             if rlib {
                 rlibs.insert(fs::realpath(path).unwrap());

src/librustc/middle/const_eval.rs

@@ -311,8 +311,8 @@ pub fn const_expr_to_pat(tcx: &ty::ctxt, expr: &Expr) -> P<ast::Pat> {
 
         ast::ExprCall(ref callee, ref args) => {
             let def = tcx.def_map.borrow()[callee.id].clone();
-            if let Vacant(entry) = tcx.def_map.borrow_mut().entry(expr.id) {
-               entry.set(def);
+            if let Vacant(entry) = tcx.def_map.borrow_mut().entry(&expr.id) {
+               entry.insert(def);
             }
             let path = match def {
                 def::DefStruct(def_id) => def_to_path(tcx, def_id),

src/librustc/middle/infer/freshen.rs

@@ -66,13 +66,13 @@ impl<'a, 'tcx> TypeFreshener<'a, 'tcx> {
             None => { }
         }
 
-        match self.freshen_map.entry(key) {
+        match self.freshen_map.entry(&key) {
             Entry::Occupied(entry) => *entry.get(),
             Entry::Vacant(entry) => {
                 let index = self.freshen_count;
                 self.freshen_count += 1;
                 let t = ty::mk_infer(self.infcx.tcx, freshener(index));
-                entry.set(t);
+                entry.insert(t);
                 t
             }
         }

src/librustc/middle/infer/region_inference/graphviz.rs

@@ -137,8 +137,8 @@ impl<'a, 'tcx> ConstraintGraph<'a, 'tcx> {
         let mut node_ids = FnvHashMap::new();
         {
             let mut add_node = |&mut : node| {
-                if let Vacant(e) = node_ids.entry(node) {
-                    e.set(i);
+                if let Vacant(e) = node_ids.entry(&node) {
+                    e.insert(i);
                     i += 1;
                 }
             };

src/librustc/middle/traits/fulfill.rs

@@ -437,8 +437,9 @@ fn register_region_obligation<'tcx>(tcx: &ty::ctxt<'tcx>,
     debug!("register_region_obligation({})",
            region_obligation.repr(tcx));
 
-    match region_obligations.entry(region_obligation.cause.body_id) {
-        Vacant(entry) => { entry.set(vec![region_obligation]); },
+    let body_id = region_obligation.cause.body_id;
+    match region_obligations.entry(&body_id) {
+        Vacant(entry) => { entry.insert(vec![region_obligation]); },
         Occupied(mut entry) => { entry.get_mut().push(region_obligation); },
     }
 

src/librustc/middle/ty.rs

@@ -78,7 +78,6 @@ use std::ops;
 use std::rc::Rc;
 use collections::enum_set::{EnumSet, CLike};
 use std::collections::{HashMap, HashSet};
-use std::collections::hash_map::Entry::{Occupied, Vacant};
 use syntax::abi;
 use syntax::ast::{CrateNum, DefId, Ident, ItemTrait, LOCAL_CRATE};
 use syntax::ast::{MutImmutable, MutMutable, Name, NamedField, NodeId};
@@ -5651,10 +5650,8 @@ pub fn lookup_field_type<'tcx>(tcx: &ctxt<'tcx>,
         node_id_to_type(tcx, id.node)
     } else {
         let mut tcache = tcx.tcache.borrow_mut();
-        let pty = match tcache.entry(id) {
-            Occupied(entry) => entry.into_mut(),
-            Vacant(entry) => entry.set(csearch::get_field_type(tcx, struct_id, id)),
-        };
+        let pty = tcache.entry(&id).get().unwrap_or_else(
+            |vacant_entry| vacant_entry.insert(csearch::get_field_type(tcx, struct_id, id)));
         pty.ty
     };
     ty.subst(tcx, substs)
@@ -6841,10 +6838,8 @@ pub fn replace_late_bound_regions<'tcx, T, F>(
         debug!("region={}", region.repr(tcx));
         match region {
             ty::ReLateBound(debruijn, br) if debruijn.depth == current_depth => {
-                * match map.entry(br) {
-                    Vacant(entry) => entry.set(mapf(br, debruijn)),
-                    Occupied(entry) => entry.into_mut(),
-                }
+                * map.entry(&br).get().unwrap_or_else(
+                      |vacant_entry| vacant_entry.insert(mapf(br, debruijn)))
             }
             _ => {
                 region