---

yaml
---
r: 41805
b: refs/heads/master
c: 4f92d8f
h: refs/heads/master
i:
  41803: 013d004
v: v3

Author: thestinger

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 9fb49088b35ae82c290ed112cdc87b71986d3d7e
+refs/heads/master: 4f92d8fb52ba335abae39bdd38e72ff42cd37bb2
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 2f46b763da2c098913884f101b6d71d69af41b49
 refs/heads/try: 3d5418789064fdb463e872a4e651af1c628a3650

trunk/src/libstd/treemap.rs

@@ -338,10 +338,24 @@ impl <T: Ord> TreeSet<T> {
 
     /// Visit the values (in-order) representing the intersection
     pure fn intersection(&self, other: &TreeSet<T>, f: fn(&T) -> bool) {
-        // FIXME: this is a naive O(n*log(m)) implementation, could be O(n + m)
-        for self.each |x| {
-            if other.contains(x) {
-                if !f(x) { break }
+        let mut x = self.iter();
+        let mut y = other.iter();
+
+        unsafe { // purity workaround
+            let mut a = x.next();
+            let mut b = y.next();
+
+            while a.is_some() && b.is_some() {
+                let a1 = a.unwrap();
+                let b1 = b.unwrap();
+                if a1 < b1 {
+                    a = x.next();
+                } else {
+                    if !(b1 < a1) {
+                        if !f(a1) { return }
+                    }
+                    b = y.next();
+                }
             }
         }
     }