From 98900d55e7f08a4b4cb665152a01b0bbf655baae Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Fri, 15 Mar 2013 21:03:29 -0400
Subject: [PATCH 1/3] add constructor to TrieSet (was missing)

---
 src/libcore/trie.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/libcore/trie.rs b/src/libcore/trie.rs
index 966db4ec66207..d6dcad334085d 100644
--- a/src/libcore/trie.rs
+++ b/src/libcore/trie.rs
@@ -137,6 +137,7 @@ impl<T> Map<uint, T> for TrieMap<T> {
 }
 
 impl<T> TrieMap<T> {
+    /// Create an empty TrieMap
     #[inline(always)]
     static pure fn new() -> TrieMap<T> {
         TrieMap{root: TrieNode::new(), length: 0}
@@ -191,6 +192,12 @@ impl Mutable for TrieSet {
 }
 
 impl TrieSet {
+    /// Create an empty TrieSet
+    #[inline(always)]
+    static pure fn new() -> TrieSet {
+        TrieSet{map: TrieMap::new()}
+    }
+
     /// Return true if the set contains a value
     #[inline(always)]
     pure fn contains(&self, value: &uint) -> bool {

From 0942c802725b4c2816f2232304cdd14b3e44cd3f Mon Sep 17 00:00:00 2001
From: Graydon Hoare <graydon@mozilla.com>
Date: Tue, 5 Mar 2013 20:54:19 -0800
Subject: [PATCH 2/3] core: fix trie chunk function

---
 src/libcore/trie.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libcore/trie.rs b/src/libcore/trie.rs
index d6dcad334085d..cf34ba774a85f 100644
--- a/src/libcore/trie.rs
+++ b/src/libcore/trie.rs
@@ -272,8 +272,8 @@ impl<T> TrieNode<T> {
 // if this was done via a trait, the key could be generic
 #[inline(always)]
 pure fn chunk(n: uint, idx: uint) -> uint {
-    let real_idx = uint::bytes - 1 - idx;
-    (n >> (SHIFT * real_idx)) & MASK
+    let sh = uint::bits - (SHIFT * (idx + 1));
+    (n >> sh) & MASK
 }
 
 fn insert<T>(count: &mut uint, child: &mut Child<T>, key: uint, value: T,

From d856215b925441a4889cb23cab5758c36e4a4746 Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Fri, 15 Mar 2013 21:43:54 -0400
Subject: [PATCH 3/3] add a test for the chunk function

---
 src/libcore/trie.rs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/libcore/trie.rs b/src/libcore/trie.rs
index cf34ba774a85f..15b0e16043431 100644
--- a/src/libcore/trie.rs
+++ b/src/libcore/trie.rs
@@ -469,4 +469,26 @@ mod tests {
             n -= 1;
         }
     }
+
+    #[test]
+    fn test_sane_chunk() {
+        let x = 1;
+        let y = 1 << (uint::bits - 1);
+
+        let mut trie = TrieSet::new();
+
+        fail_unless!(trie.insert(x));
+        fail_unless!(trie.insert(y));
+
+        fail_unless!(trie.len() == 2);
+
+        let expected = [x, y];
+
+        let mut i = 0;
+
+        for trie.each |x| {
+            fail_unless!(expected[i] == *x);
+            i += 1;
+        }
+    }
 }