---

yaml
---
r: 142451
b: refs/heads/try2
c: 8a32676
h: refs/heads/master
i:
  142449: a854bb6
  142447: e8e6c9e
v: v3

Author: blake2-ppc

[refs]

@@ -5,7 +5,7 @@ refs/heads/snap-stage3: 78a7676898d9f80ab540c6df5d4c9ce35bb50463
 refs/heads/try: 519addf6277dbafccbb4159db4b710c37eaa2ec5
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
-refs/heads/try2: 75015c36f9fa6d0958874c1a448d6d67056145ae
+refs/heads/try2: 8a3267672c43e7cc116e588dd21998d14fc21ba4
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try2/src/libextra/deque.rs

@@ -108,7 +108,7 @@ impl<T> Deque<T> {
     /// Prepend an element to the deque
     pub fn add_front(&mut self, t: T) {
         if self.nelts == self.elts.len() {
-            grow(self.nelts, self.lo, &mut self.elts);
+            grow(self.nelts, &mut self.lo, &mut self.elts);
         }
         if self.lo == 0u {
             self.lo = self.elts.len() - 1u;
@@ -120,7 +120,7 @@ impl<T> Deque<T> {
     /// Append an element to the deque
     pub fn add_back(&mut self, t: T) {
         if self.nelts == self.elts.len() {
-            grow(self.nelts, self.lo, &mut self.elts);
+            grow(self.nelts, &mut self.lo, &mut self.elts);
         }
         let hi = self.raw_index(self.nelts);
         self.elts[hi] = Some(t);
@@ -230,18 +230,36 @@ iterator!{impl DequeMutRevIterator -> &'self mut T, get_mut_ref, -1}
 
 /// Grow is only called on full elts, so nelts is also len(elts), unlike
 /// elsewhere.
-fn grow<T>(nelts: uint, lo: uint, elts: &mut ~[Option<T>]) {
+fn grow<T>(nelts: uint, loptr: &mut uint, elts: &mut ~[Option<T>]) {
     assert_eq!(nelts, elts.len());
-    let newlen = elts.capacity() * 2;
+    let lo = *loptr;
+    let newlen = nelts * 2;
     elts.reserve(newlen);
 
     /* fill with None */
     for uint::range(elts.len(), elts.capacity()) |_| {
         elts.push(None);
     }
-    /* move the former wraparound to the new half */
-    for uint::range(0, lo) |i| {
-        elts.swap(i, nelts + i);
+
+    /*
+      Move the shortest half into the newly reserved area.
+      lo ---->|
+      nelts ----------->|
+        [o o o|o o o o o]
+      A [. . .|o o o o o o o o|. . . . .]
+      B [o o o|. . . . . . . .|o o o o o]
+     */
+
+    assert!(newlen - nelts/2 >= nelts);
+    if lo <= (nelts - lo) { // A
+        for uint::range(0, lo) |i| {
+            elts.swap(i, nelts + i);
+        }
+    } else {                // B
+        for uint::range(lo, nelts) |i| {
+            elts.swap(i, newlen - nelts + i);
+        }
+        *loptr += newlen - nelts;
     }
 }