From 01b599eb34125b7bc4d01fd7cc24876179ad6798 Mon Sep 17 00:00:00 2001
From: Joseph Crail <jbcrail@gmail.com>
Date: Fri, 7 Nov 2014 17:51:38 -0500
Subject: [PATCH 1/2] Add BitXor to EnumSet.

---
 src/libcollections/enum_set.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
index 1acdaef9c91c1..0737620690b6f 100644
--- a/src/libcollections/enum_set.rs
+++ b/src/libcollections/enum_set.rs
@@ -16,7 +16,6 @@
 use core::prelude::*;
 use core::fmt;
 
-// FIXME(conventions): implement BitXor
 // FIXME(contentions): implement union family of methods? (general design may be wrong here)
 // FIXME(conventions): implement len
 
@@ -196,6 +195,12 @@ impl<E:CLike> BitAnd<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
     }
 }
 
+impl<E:CLike> BitXor<EnumSet<E>, EnumSet<E>> for EnumSet<E> {
+    fn bitxor(&self, e: &EnumSet<E>) -> EnumSet<E> {
+        EnumSet {bits: self.bits ^ e.bits}
+    }
+}
+
 /// An iterator over an EnumSet
 pub struct Items<E> {
     index: uint,

From 12db4de554faf8e2f6baca4514b1e5983cb60783 Mon Sep 17 00:00:00 2001
From: Joseph Crail <jbcrail@gmail.com>
Date: Fri, 7 Nov 2014 18:46:29 -0500
Subject: [PATCH 2/2] Add tests for BitAnd and BitXor.

---
 src/libcollections/enum_set.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/libcollections/enum_set.rs b/src/libcollections/enum_set.rs
index 0737620690b6f..b2b26914b441a 100644
--- a/src/libcollections/enum_set.rs
+++ b/src/libcollections/enum_set.rs
@@ -403,9 +403,29 @@ mod test {
         let elems = e_intersection.iter().collect();
         assert_eq!(vec![C], elems)
 
+        // Another way to express intersection
+        let e_intersection = e1 - (e1 - e2);
+        let elems = e_intersection.iter().collect();
+        assert_eq!(vec![C], elems)
+
         let e_subtract = e1 - e2;
         let elems = e_subtract.iter().collect();
         assert_eq!(vec![A], elems)
+
+        // Bitwise XOR of two sets, aka symmetric difference
+        let e_symmetric_diff = e1 ^ e2;
+        let elems = e_symmetric_diff.iter().collect();
+        assert_eq!(vec![A,B], elems)
+
+        // Another way to express symmetric difference
+        let e_symmetric_diff = (e1 - e2) | (e2 - e1);
+        let elems = e_symmetric_diff.iter().collect();
+        assert_eq!(vec![A,B], elems)
+
+        // Yet another way to express symmetric difference
+        let e_symmetric_diff = (e1 | e2) - (e1 & e2);
+        let elems = e_symmetric_diff.iter().collect();
+        assert_eq!(vec![A,B], elems)
     }
 
     #[test]