core: use assoc types in Deref[Mut]

Author: Jorge Aparicio

src/liballoc/arc.rs

@@ -247,7 +247,9 @@ impl<T> BorrowFrom<Arc<T>> for T {
 }
 
 #[experimental = "Deref is experimental."]
-impl<T> Deref<T> for Arc<T> {
+impl<T> Deref for Arc<T> {
+    type Target = T;
+
     #[inline]
     fn deref(&self) -> &T {
         &self.inner().data

src/liballoc/boxed.rs

@@ -153,11 +153,13 @@ impl fmt::Show for Box<Any+'static> {
     }
 }
 
-impl<Sized? T> Deref<T> for Box<T> {
+impl<Sized? T> Deref for Box<T> {
+    type Target = T;
+
     fn deref(&self) -> &T { &**self }
 }
 
-impl<Sized? T> DerefMut<T> for Box<T> {
+impl<Sized? T> DerefMut for Box<T> {
     fn deref_mut(&mut self) -> &mut T { &mut **self }
 }
 
@@ -210,7 +212,7 @@ mod test {
 
     #[test]
     fn deref() {
-        fn homura<T: Deref<i32>>(_: T) { }
+        fn homura<T: Deref<Target=i32>>(_: T) { }
         homura(box 765i32);
     }
 }

src/liballoc/lib.rs

@@ -65,6 +65,7 @@
 
 #![no_std]
 #![feature(lang_items, phase, unsafe_destructor, default_type_params)]
+#![feature(associated_types)]
 
 #[phase(plugin, link)]
 extern crate core;

src/liballoc/rc.rs

@@ -355,7 +355,9 @@ impl<T> BorrowFrom<Rc<T>> for T {
 }
 
 #[experimental = "Deref is experimental."]
-impl<T> Deref<T> for Rc<T> {
+impl<T> Deref for Rc<T> {
+    type Target = T;
+
     #[inline(always)]
     fn deref(&self) -> &T {
         &self.inner().value

src/libcollections/btree/map.rs

@@ -515,13 +515,15 @@ mod stack {
         marker: marker::InvariantLifetime<'id>
     }
 
-    impl<'id, T> Deref<T> for IdRef<'id, T> {
+    impl<'id, T> Deref for IdRef<'id, T> {
+        type Target = T;
+
         fn deref(&self) -> &T {
             &*self.inner
         }
     }
 
-    impl<'id, T> DerefMut<T> for IdRef<'id, T> {
+    impl<'id, T> DerefMut for IdRef<'id, T> {
         fn deref_mut(&mut self) -> &mut T {
             &mut *self.inner
         }

src/libcollections/btree/node.rs

@@ -455,7 +455,9 @@ impl<K: Clone, V: Clone> Clone for Node<K, V> {
 ///     flag: &'a Cell<bool>,
 /// }
 ///
-/// impl<'a> Deref<Node<uint, uint>> for Nasty<'a> {
+/// impl<'a> Deref for Nasty<'a> {
+///     type Target = Node<uint, uint>;
+///
 ///     fn deref(&self) -> &Node<uint, uint> {
 ///         if self.flag.get() {
 ///             &*self.second
@@ -511,7 +513,7 @@ impl<K: Ord, V> Node<K, V> {
     /// Searches for the given key in the node. If it finds an exact match,
     /// `Found` will be yielded with the matching index. If it doesn't find an exact match,
     /// `GoDown` will be yielded with the index of the subtree the key must lie in.
-    pub fn search<Sized? Q, NodeRef: Deref<Node<K, V>>>(node: NodeRef, key: &Q)
+    pub fn search<Sized? Q, NodeRef: Deref<Target=Node<K, V>>>(node: NodeRef, key: &Q)
                   -> SearchResult<NodeRef> where Q: BorrowFrom<K> + Ord {
         // FIXME(Gankro): Tune when to search linear or binary based on B (and maybe K/V).
         // For the B configured as of this writing (B = 6), binary search was *significantly*
@@ -588,7 +590,7 @@ impl <K, V> Node<K, V> {
     }
 }
 
-impl<K, V, NodeRef: Deref<Node<K, V>>, Type, NodeType> Handle<NodeRef, Type, NodeType> {
+impl<K, V, NodeRef: Deref<Target=Node<K, V>>, Type, NodeType> Handle<NodeRef, Type, NodeType> {
     /// Returns a reference to the node that contains the pointed-to edge or key/value pair. This
     /// is very different from `edge` and `edge_mut` because those return children of the node
     /// returned by `node`.
@@ -597,7 +599,9 @@ impl<K, V, NodeRef: Deref<Node<K, V>>, Type, NodeType> Handle<NodeRef, Type, Nod
     }
 }
 
-impl<K, V, NodeRef: DerefMut<Node<K, V>>, Type, NodeType> Handle<NodeRef, Type, NodeType> {
+impl<K, V, NodeRef, Type, NodeType> Handle<NodeRef, Type, NodeType> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Converts a handle into one that stores the same information using a raw pointer. This can
     /// be useful in conjunction with `from_raw` when the type system is insufficient for
     /// determining the lifetimes of the nodes.
@@ -653,7 +657,7 @@ impl<'a, K: 'a, V: 'a> Handle<&'a mut Node<K, V>, handle::Edge, handle::Internal
     }
 }
 
-impl<K, V, NodeRef: Deref<Node<K, V>>> Handle<NodeRef, handle::Edge, handle::Internal> {
+impl<K, V, NodeRef: Deref<Target=Node<K, V>>> Handle<NodeRef, handle::Edge, handle::Internal> {
     // This doesn't exist because there are no uses for it,
     // but is fine to add, analagous to edge_mut.
     //
@@ -667,7 +671,7 @@ pub enum ForceResult<NodeRef, Type> {
     Internal(Handle<NodeRef, Type, handle::Internal>)
 }
 
-impl<K, V, NodeRef: Deref<Node<K, V>>, Type> Handle<NodeRef, Type, handle::LeafOrInternal> {
+impl<K, V, NodeRef: Deref<Target=Node<K, V>>, Type> Handle<NodeRef, Type, handle::LeafOrInternal> {
     /// Figure out whether this handle is pointing to something in a leaf node or to something in
     /// an internal node, clarifying the type according to the result.
     pub fn force(self) -> ForceResult<NodeRef, Type> {
@@ -684,8 +688,9 @@ impl<K, V, NodeRef: Deref<Node<K, V>>, Type> Handle<NodeRef, Type, handle::LeafO
         }
     }
 }
-
-impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::Edge, handle::Leaf> {
+impl<K, V, NodeRef> Handle<NodeRef, handle::Edge, handle::Leaf> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Tries to insert this key-value pair at the given index in this leaf node
     /// If the node is full, we have to split it.
     ///
@@ -717,7 +722,9 @@ impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::Edge, handle::
     }
 }
 
-impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::Edge, handle::Internal> {
+impl<K, V, NodeRef> Handle<NodeRef, handle::Edge, handle::Internal> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Returns a mutable reference to the edge pointed-to by this handle. This should not be
     /// confused with `node`, which references the parent node of what is returned here.
     pub fn edge_mut(&mut self) -> &mut Node<K, V> {
@@ -800,7 +807,9 @@ impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::Edge, handle::
     }
 }
 
-impl<K, V, NodeRef: DerefMut<Node<K, V>>, NodeType> Handle<NodeRef, handle::Edge, NodeType> {
+impl<K, V, NodeRef, NodeType> Handle<NodeRef, handle::Edge, NodeType> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Gets the handle pointing to the key/value pair just to the left of the pointed-to edge.
     /// This is unsafe because the handle might point to the first edge in the node, which has no
     /// pair to its left.
@@ -862,7 +871,7 @@ impl<'a, K: 'a, V: 'a, NodeType> Handle<&'a mut Node<K, V>, handle::KV, NodeType
     }
 }
 
-impl<'a, K: 'a, V: 'a, NodeRef: Deref<Node<K, V>> + 'a, NodeType> Handle<NodeRef, handle::KV,
+impl<'a, K: 'a, V: 'a, NodeRef: Deref<Target=Node<K, V>> + 'a, NodeType> Handle<NodeRef, handle::KV,
                                                                          NodeType> {
     // These are fine to include, but are currently unneeded.
     //
@@ -881,8 +890,9 @@ impl<'a, K: 'a, V: 'a, NodeRef: Deref<Node<K, V>> + 'a, NodeType> Handle<NodeRef
     // }
 }
 
-impl<'a, K: 'a, V: 'a, NodeRef: DerefMut<Node<K, V>> + 'a, NodeType> Handle<NodeRef, handle::KV,
-                                                                            NodeType> {
+impl<'a, K: 'a, V: 'a, NodeRef, NodeType> Handle<NodeRef, handle::KV, NodeType> where
+    NodeRef: 'a + Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Returns a mutable reference to the key pointed-to by this handle. This doesn't return a
     /// reference with a lifetime as large as `into_kv_mut`, but it also does not consume the
     /// handle.
@@ -898,7 +908,9 @@ impl<'a, K: 'a, V: 'a, NodeRef: DerefMut<Node<K, V>> + 'a, NodeType> Handle<Node
     }
 }
 
-impl<K, V, NodeRef: DerefMut<Node<K, V>>, NodeType> Handle<NodeRef, handle::KV, NodeType> {
+impl<K, V, NodeRef, NodeType> Handle<NodeRef, handle::KV, NodeType> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Gets the handle pointing to the edge immediately to the left of the key/value pair pointed
     /// to by this handle.
     pub fn left_edge<'a>(&'a mut self) -> Handle<&'a mut Node<K, V>, handle::Edge, NodeType> {
@@ -918,7 +930,9 @@ impl<K, V, NodeRef: DerefMut<Node<K, V>>, NodeType> Handle<NodeRef, handle::KV,
     }
 }
 
-impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::KV, handle::Leaf> {
+impl<K, V, NodeRef> Handle<NodeRef, handle::KV, handle::Leaf> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut,
+{
     /// Removes the key/value pair at the handle's location.
     ///
     /// # Panics (in debug build)
@@ -929,7 +943,9 @@ impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::KV, handle::Le
     }
 }
 
-impl<K, V, NodeRef: DerefMut<Node<K, V>>> Handle<NodeRef, handle::KV, handle::Internal> {
+impl<K, V, NodeRef> Handle<NodeRef, handle::KV, handle::Internal> where
+    NodeRef: Deref<Target=Node<K, V>> + DerefMut
+{
     /// Steal! Stealing is roughly analogous to a binary tree rotation.
     /// In this case, we're "rotating" right.
     unsafe fn steal_rightward(&mut self) {

src/libcollections/string.rs

@@ -935,7 +935,9 @@ impl ops::Slice<uint, str> for String {
 }
 
 #[experimental = "waiting on Deref stabilization"]
-impl ops::Deref<str> for String {
+impl ops::Deref for String {
+    type Target = str;
+
     fn deref<'a>(&'a self) -> &'a str {
         unsafe { mem::transmute(self.vec[]) }
     }
@@ -947,7 +949,9 @@ pub struct DerefString<'a> {
     x: DerefVec<'a, u8>
 }
 
-impl<'a> Deref<String> for DerefString<'a> {
+impl<'a> Deref for DerefString<'a> {
+    type Target = String;
+
     fn deref<'b>(&'b self) -> &'b String {
         unsafe { mem::transmute(&*self.x) }
     }

src/libcollections/vec.rs

@@ -1301,12 +1301,14 @@ impl<T> ops::SliceMut<uint, [T]> for Vec<T> {
 }
 
 #[experimental = "waiting on Deref stability"]
-impl<T> ops::Deref<[T]> for Vec<T> {
+impl<T> ops::Deref for Vec<T> {
+    type Target = [T];
+
     fn deref<'a>(&'a self) -> &'a [T] { self.as_slice() }
 }
 
 #[experimental = "waiting on DerefMut stability"]
-impl<T> ops::DerefMut<[T]> for Vec<T> {
+impl<T> ops::DerefMut for Vec<T> {
     fn deref_mut<'a>(&'a mut self) -> &'a mut [T] { self.as_mut_slice() }
 }
 
@@ -1716,7 +1718,9 @@ pub struct DerefVec<'a, T> {
 }
 
 #[experimental]
-impl<'a, T> Deref<Vec<T>> for DerefVec<'a, T> {
+impl<'a, T> Deref for DerefVec<'a, T> {
+    type Target = Vec<T>;
+
     fn deref<'b>(&'b self) -> &'b Vec<T> {
         &self.x
     }

src/libcore/array.rs

@@ -54,7 +54,7 @@ macro_rules! array_impls {
             #[stable]
             impl<'a, A, B, Rhs> PartialEq<Rhs> for [A; $N] where
                 A: PartialEq<B>,
-                Rhs: Deref<[B]>,
+                Rhs: Deref<Target=[B]>,
             {
                 #[inline(always)]
                 fn eq(&self, other: &Rhs) -> bool { PartialEq::eq(self[], &**other) }
@@ -65,7 +65,7 @@ macro_rules! array_impls {
             #[stable]
             impl<'a, A, B, Lhs> PartialEq<[B; $N]> for Lhs where
                 A: PartialEq<B>,
-                Lhs: Deref<[A]>
+                Lhs: Deref<Target=[A]>
             {
                 #[inline(always)]
                 fn eq(&self, other: &[B; $N]) -> bool { PartialEq::eq(&**self, other[]) }

src/libcore/borrow.rs

@@ -191,7 +191,9 @@ impl<'a, T, Sized? B> Cow<'a, T, B> where B: ToOwned<T> {
     }
 }
 
-impl<'a, T, Sized? B> Deref<B> for Cow<'a, T, B> where B: ToOwned<T>  {
+impl<'a, T, Sized? B> Deref for Cow<'a, T, B> where B: ToOwned<T>  {
+    type Target = B;
+
     fn deref(&self) -> &B {
         match *self {
             Borrowed(borrowed) => borrowed,