collections: Enable IndexMut for some collections

This commit enables implementations of IndexMut for a number of collections,
including Vec, RingBuf, SmallIntMap, TrieMap, TreeMap, and HashMap. At the same
time this deprecates the `get_mut` methods on vectors in favor of using the
indexing notation.

cc #18424

Author: alexcrichton

src/compiletest/runtest.rs

@@ -1013,7 +1013,7 @@ fn check_expected_errors(expected_errors: Vec<errors::ExpectedError> ,
                 if prefix_matches(line, prefixes[i].as_slice()) &&
                     line.contains(ee.kind.as_slice()) &&
                     line.contains(ee.msg.as_slice()) {
-                    *found_flags.get_mut(i) = true;
+                    found_flags[i] = true;
                     was_expected = true;
                     break;
                 }

src/libcollections/bitv.rs

@@ -243,7 +243,7 @@ impl Bitv {
         let used_bits = bitv.nbits % u32::BITS;
         if init && used_bits != 0 {
             let largest_used_word = (bitv.nbits + u32::BITS - 1) / u32::BITS - 1;
-            *bitv.storage.get_mut(largest_used_word) &= (1 << used_bits) - 1;
+            bitv.storage[largest_used_word] &= (1 << used_bits) - 1;
         }
 
         bitv
@@ -297,8 +297,9 @@ impl Bitv {
         let w = i / u32::BITS;
         let b = i % u32::BITS;
         let flag = 1 << b;
-        *self.storage.get_mut(w) = if x { self.storage[w] | flag }
-                          else { self.storage[w] & !flag };
+        let val = if x { self.storage[w] | flag }
+                  else { self.storage[w] & !flag };
+        self.storage[w] = val;
     }
 
     /// Sets all bits to 1.
@@ -617,7 +618,7 @@ impl Bitv {
             self.storage.truncate(word_len);
             if len % u32::BITS > 0 {
                 let mask = (1 << len % u32::BITS) - 1;
-                *self.storage.get_mut(word_len - 1) &= mask;
+                self.storage[word_len - 1] &= mask;
             }
         }
     }
@@ -681,15 +682,15 @@ impl Bitv {
             let overhang = self.nbits % u32::BITS; // # of already-used bits
             let mask = !((1 << overhang) - 1);  // e.g. 5 unused bits => 111110....0
             if value {
-                *self.storage.get_mut(old_last_word) |= mask;
+                self.storage[old_last_word] |= mask;
             } else {
-                *self.storage.get_mut(old_last_word) &= !mask;
+                self.storage[old_last_word] &= !mask;
             }
         }
         // Fill in words after the old tail word
         let stop_idx = cmp::min(self.storage.len(), new_nwords);
         for idx in range(old_last_word + 1, stop_idx) {
-            *self.storage.get_mut(idx) = full_value;
+            self.storage[idx] = full_value;
         }
         // Allocate new words, if needed
         if new_nwords > self.storage.len() {
@@ -700,7 +701,7 @@ impl Bitv {
             if value {
                 let tail_word = new_nwords - 1;
                 let used_bits = new_nbits % u32::BITS;
-                *self.storage.get_mut(tail_word) &= (1 << used_bits) - 1;
+                self.storage[tail_word] &= (1 << used_bits) - 1;
             }
         }
         // Adjust internal bit count
@@ -728,7 +729,7 @@ impl Bitv {
         let ret = self.get(self.nbits - 1);
         // If we are unusing a whole word, make sure it is zeroed out
         if self.nbits % u32::BITS == 1 {
-            *self.storage.get_mut(self.nbits / u32::BITS) = 0;
+            self.storage[self.nbits / u32::BITS] = 0;
         }
         self.nbits -= 1;
         ret
@@ -1184,7 +1185,7 @@ impl BitvSet {
         for (i, w) in other_words {
             let old = self_bitv.storage[i];
             let new = f(old, w);
-            *self_bitv.storage.get_mut(i) = new;
+            self_bitv.storage[i] = new;
         }
     }
 

src/libcollections/btree/map.rs

@@ -690,6 +690,12 @@ impl<K: Ord, V> Index<K, V> for BTreeMap<K, V> {
     }
 }
 
+impl<K: Ord, V> IndexMut<K, V> for BTreeMap<K, V> {
+    fn index_mut(&mut self, key: &K) -> &mut V {
+        self.find_mut(key).expect("no entry found for key")
+    }
+}
+
 /// Genericises over how to get the correct type of iterator from the correct type
 /// of Node ownership.
 trait Traverse<N> {

src/libcollections/priority_queue.rs

@@ -71,7 +71,7 @@
 //!     let mut pq = PriorityQueue::new();
 //!
 //!     // We're at `start`, with a zero cost
-//!     *dist.get_mut(start) = 0u;
+//!     dist[start] = 0u;
 //!     pq.push(State { cost: 0u, position: start });
 //!
 //!     // Examine the frontier with lower cost nodes first (min-heap)
@@ -96,7 +96,7 @@
 //!             if next.cost < dist[next.position] {
 //!                 pq.push(next);
 //!                 // Relaxation, we have now found a better way
-//!                 *dist.get_mut(next.position) = next.cost;
+//!                 dist[next.position] = next.cost;
 //!             }
 //!         }
 //!     }
@@ -330,7 +330,7 @@ impl<T: Ord> PriorityQueue<T> {
             None           => { None }
             Some(mut item) => {
                 if !self.is_empty() {
-                    swap(&mut item, self.data.get_mut(0));
+                    swap(&mut item, &mut self.data[0]);
                     self.siftdown(0);
                 }
                 Some(item)
@@ -378,7 +378,7 @@ impl<T: Ord> PriorityQueue<T> {
     /// ```
     pub fn push_pop(&mut self, mut item: T) -> T {
         if !self.is_empty() && *self.top().unwrap() > item {
-            swap(&mut item, self.data.get_mut(0));
+            swap(&mut item, &mut self.data[0]);
             self.siftdown(0);
         }
         item
@@ -402,7 +402,7 @@ impl<T: Ord> PriorityQueue<T> {
     /// ```
     pub fn replace(&mut self, mut item: T) -> Option<T> {
         if !self.is_empty() {
-            swap(&mut item, self.data.get_mut(0));
+            swap(&mut item, &mut self.data[0]);
             self.siftdown(0);
             Some(item)
         } else {
@@ -462,40 +462,40 @@ impl<T: Ord> PriorityQueue<T> {
     // compared to using swaps, which involves twice as many moves.
     fn siftup(&mut self, start: uint, mut pos: uint) {
         unsafe {
-            let new = replace(self.data.get_mut(pos), zeroed());
+            let new = replace(&mut self.data[pos], zeroed());
 
             while pos > start {
                 let parent = (pos - 1) >> 1;
                 if new > self.data[parent] {
-                    let x = replace(self.data.get_mut(parent), zeroed());
-                    ptr::write(self.data.get_mut(pos), x);
+                    let x = replace(&mut self.data[parent], zeroed());
+                    ptr::write(&mut self.data[pos], x);
                     pos = parent;
                     continue
                 }
                 break
             }
-            ptr::write(self.data.get_mut(pos), new);
+            ptr::write(&mut self.data[pos], new);
         }
     }
 
     fn siftdown_range(&mut self, mut pos: uint, end: uint) {
         unsafe {
             let start = pos;
-            let new = replace(self.data.get_mut(pos), zeroed());
+            let new = replace(&mut self.data[pos], zeroed());
 
             let mut child = 2 * pos + 1;
             while child < end {
                 let right = child + 1;
                 if right < end && !(self.data[child] > self.data[right]) {
                     child = right;
                 }
-                let x = replace(self.data.get_mut(child), zeroed());
-                ptr::write(self.data.get_mut(pos), x);
+                let x = replace(&mut self.data[child], zeroed());
+                ptr::write(&mut self.data[pos], x);
                 pos = child;
                 child = 2 * pos + 1;
             }
 
-            ptr::write(self.data.get_mut(pos), new);
+            ptr::write(&mut self.data[pos], new);
             self.siftup(start, pos);
         }
     }

src/libcollections/ringbuf.rs

@@ -58,7 +58,7 @@ impl<T> Deque<T> for RingBuf<T> {
 
     /// Returns a mutable reference to the first element in the `RingBuf`.
     fn front_mut<'a>(&'a mut self) -> Option<&'a mut T> {
-        if self.nelts > 0 { Some(self.get_mut(0)) } else { None }
+        if self.nelts > 0 { Some(&mut self[0]) } else { None }
     }
 
     /// Returns a reference to the last element in the `RingBuf`.
@@ -69,13 +69,13 @@ impl<T> Deque<T> for RingBuf<T> {
     /// Returns a mutable reference to the last element in the `RingBuf`.
     fn back_mut<'a>(&'a mut self) -> Option<&'a mut T> {
         let nelts = self.nelts;
-        if nelts > 0 { Some(self.get_mut(nelts - 1)) } else { None }
+        if nelts > 0 { Some(&mut self[nelts - 1]) } else { None }
     }
 
     /// Removes and returns the first element in the `RingBuf`, or `None` if it
     /// is empty.
     fn pop_front(&mut self) -> Option<T> {
-        let result = self.elts.get_mut(self.lo).take();
+        let result = self.elts[self.lo].take();
         if result.is_some() {
             self.lo = (self.lo + 1u) % self.elts.len();
             self.nelts -= 1u;
@@ -91,7 +91,7 @@ impl<T> Deque<T> for RingBuf<T> {
         if self.lo == 0u {
             self.lo = self.elts.len() - 1u;
         } else { self.lo -= 1u; }
-        *self.elts.get_mut(self.lo) = Some(t);
+        self.elts[self.lo] = Some(t);
         self.nelts += 1u;
     }
 }
@@ -102,14 +102,14 @@ impl<T> MutableSeq<T> for RingBuf<T> {
             grow(self.nelts, &mut self.lo, &mut self.elts);
         }
         let hi = self.raw_index(self.nelts);
-        *self.elts.get_mut(hi) = Some(t);
+        self.elts[hi] = Some(t);
         self.nelts += 1u;
     }
     fn pop(&mut self) -> Option<T> {
         if self.nelts > 0 {
             self.nelts -= 1;
             let hi = self.raw_index(self.nelts);
-            self.elts.get_mut(hi).take()
+            self.elts[hi].take()
         } else {
             None
         }
@@ -140,6 +140,7 @@ impl<T> RingBuf<T> {
     /// # Example
     ///
     /// ```rust
+    /// # #![allow(deprecated)]
     /// use std::collections::RingBuf;
     ///
     /// let mut buf = RingBuf::new();
@@ -149,12 +150,9 @@ impl<T> RingBuf<T> {
     /// *buf.get_mut(1) = 7;
     /// assert_eq!(buf[1], 7);
     /// ```
+    #[deprecated = "use indexing instead: `buf[index] = value`"]
     pub fn get_mut<'a>(&'a mut self, i: uint) -> &'a mut T {
-        let idx = self.raw_index(i);
-        match *self.elts.get_mut(idx) {
-            None => panic!(),
-            Some(ref mut v) => v
-        }
+        &mut self[i]
     }
 
     /// Swaps elements at indices `i` and `j`.
@@ -466,13 +464,16 @@ impl<A> Index<uint, A> for RingBuf<A> {
     }
 }
 
-// FIXME(#12825) Indexing will always try IndexMut first and that causes issues.
-/*impl<A> IndexMut<uint, A> for RingBuf<A> {
+impl<A> IndexMut<uint, A> for RingBuf<A> {
     #[inline]
-    fn index_mut<'a>(&'a mut self, index: &uint) -> &'a mut A {
-        self.get_mut(*index)
+    fn index_mut<'a>(&'a mut self, i: &uint) -> &'a mut A {
+        let idx = self.raw_index(*i);
+        match *(&mut self.elts[idx]) {
+            None => panic!(),
+            Some(ref mut v) => v
+        }
     }
-}*/
+}
 
 impl<A> FromIterator<A> for RingBuf<A> {
     fn from_iter<T: Iterator<A>>(iterator: T) -> RingBuf<A> {

src/libcollections/smallintmap.rs

@@ -100,7 +100,7 @@ impl<V> MutableMap<uint, V> for SmallIntMap<V> {
     /// Returns a mutable reference to the value corresponding to the key.
     fn find_mut<'a>(&'a mut self, key: &uint) -> Option<&'a mut V> {
         if *key < self.v.len() {
-            match *self.v.get_mut(*key) {
+            match *self.v.index_mut(key) {
               Some(ref mut value) => Some(value),
               None => None
             }
@@ -118,7 +118,7 @@ impl<V> MutableMap<uint, V> for SmallIntMap<V> {
         if len <= key {
             self.v.grow_fn(key - len + 1, |_| None);
         }
-        *self.v.get_mut(key) = Some(value);
+        self.v[key] = Some(value);
         !exists
     }
 
@@ -145,7 +145,7 @@ impl<V> MutableMap<uint, V> for SmallIntMap<V> {
         if *key >= self.v.len() {
             return None;
         }
-        self.v.get_mut(*key).take()
+        self.v[*key].take()
     }
 }
 
@@ -405,13 +405,12 @@ impl<V> Index<uint, V> for SmallIntMap<V> {
     }
 }
 
-// FIXME(#12825) Indexing will always try IndexMut first and that causes issues.
-/*impl<V> IndexMut<uint, V> for SmallIntMap<V> {
+impl<V> IndexMut<uint, V> for SmallIntMap<V> {
     #[inline]
     fn index_mut<'a>(&'a mut self, i: &uint) -> &'a mut V {
         self.find_mut(i).expect("key not present")
     }
-}*/
+}
 
 macro_rules! iterator {
     (impl $name:ident -> $elem:ty, $($getter:ident),+) => {

src/libcollections/str.rs

@@ -692,17 +692,17 @@ pub trait StrAllocating: Str {
         for (i, sc) in me.chars().enumerate() {
 
             let mut current = i;
-            *dcol.get_mut(0) = current + 1;
+            dcol[0] = current + 1;
 
             for (j, tc) in t.chars().enumerate() {
 
                 let next = dcol[j + 1];
 
                 if sc == tc {
-                    *dcol.get_mut(j + 1) = current;
+                    dcol[j + 1] = current;
                 } else {
-                    *dcol.get_mut(j + 1) = cmp::min(current, next);
-                    *dcol.get_mut(j + 1) = cmp::min(dcol[j + 1], dcol[j]) + 1;
+                    dcol[j + 1] = cmp::min(current, next);
+                    dcol[j + 1] = cmp::min(dcol[j + 1], dcol[j]) + 1;
                 }
 
                 current = next;

src/libcollections/treemap.rs

@@ -257,12 +257,12 @@ impl<K: Ord, V> Index<K, V> for TreeMap<K, V> {
     }
 }
 
-/*impl<K: Ord, V> IndexMut<K, V> for TreeMap<K, V> {
+impl<K: Ord, V> IndexMut<K, V> for TreeMap<K, V> {
     #[inline]
     fn index_mut<'a>(&'a mut self, i: &K) -> &'a mut V {
         self.find_mut(i).expect("no entry found for key")
     }
-}*/
+}
 
 impl<K: Ord, V> TreeMap<K, V> {
     /// Creates an empty `TreeMap`.

src/libcollections/trie.rs

@@ -515,13 +515,12 @@ impl<T> Index<uint, T> for TrieMap<T> {
     }
 }
 
-// FIXME(#12825) Indexing will always try IndexMut first and that causes issues.
-/*impl<T> IndexMut<uint, T> for TrieMap<T> {
+impl<T> IndexMut<uint, T> for TrieMap<T> {
     #[inline]
     fn index_mut<'a>(&'a mut self, i: &uint) -> &'a mut T {
         self.find_mut(i).expect("key not present")
     }
-}*/
+}
 
 /// A set implemented as a radix trie.
 ///