add difference and symmetric_difference to Set

src/libcore/container.rs

@@ -75,4 +75,10 @@ pub trait Set<T>: Mutable {
 
     /// Return true if the set is a superset of another
     pure fn is_superset(&self, other: &self) -> bool;
+
+    /// Visit the values representing the difference
+    pure fn difference(&self, other: &self, f: fn(&T) -> bool);
+
+    /// Visit the values representing the symmetric difference
+    pure fn symmetric_difference(&self, other: &self, f: fn(&T) -> bool);
 }

src/libcore/hashmap.rs

@@ -469,6 +469,22 @@ pub mod linear {
         pure fn is_superset(&self, other: &LinearSet<T>) -> bool {
             other.is_subset(self)
         }
+
+        /// Visit the values representing the difference
+        pure fn difference(&self, other: &LinearSet<T>, f: fn(&T) -> bool) {
+            for self.each |v| {
+                if !other.contains(v) {
+                    if !f(v) { return; }
+                }
+            }
+        }
+
+        /// Visit the values representing the symmetric difference
+        pure fn symmetric_difference(&self, other: &LinearSet<T>,
+                                     f: fn(&T) -> bool) {
+            self.difference(other, f);
+            other.difference(self, f);
+        }
     }
 
     pub impl <T: Hash IterBytes Eq> LinearSet<T> {
@@ -681,4 +697,53 @@ mod test_set {
         assert !b.is_subset(&a);
         assert b.is_superset(&a);
     }
+
+    #[test]
+    fn test_difference() {
+        let mut a = linear::LinearSet::new();
+        let mut b = linear::LinearSet::new();
+
+        assert a.insert(1);
+        assert a.insert(3);
+        assert a.insert(5);
+        assert a.insert(9);
+        assert a.insert(11);
+
+        assert b.insert(3);
+        assert b.insert(9);
+
+        let mut i = 0;
+        let expected = [1, 5, 11];
+        for a.difference(&b) |x| {
+            assert vec::contains(expected, x);
+            i += 1
+        }
+        assert i == expected.len();
+    }
+
+    #[test]
+    fn test_symmetric_difference() {
+        let mut a = linear::LinearSet::new();
+        let mut b = linear::LinearSet::new();
+
+        assert a.insert(1);
+        assert a.insert(3);
+        assert a.insert(5);
+        assert a.insert(9);
+        assert a.insert(11);
+
+        assert b.insert(-2);
+        assert b.insert(3);
+        assert b.insert(9);
+        assert b.insert(14);
+        assert b.insert(22);
+
+        let mut i = 0;
+        let expected = [-2, 1, 5, 11, 14, 22];
+        for a.symmetric_difference(&b) |x| {
+            assert vec::contains(expected, x);
+            i += 1
+        }
+        assert i == expected.len();
+    }
 }

src/libstd/treemap.rs

@@ -29,10 +29,10 @@ use core::prelude::*;
 // range search - O(log n) retrieval of an iterator from some key
 
 // (possibly) implement the overloads Python does for sets:
-//   * union: |
 //   * intersection: &
 //   * difference: -
 //   * symmetric difference: ^
+//   * union: |
 // These would be convenient since the methods work like `each`
 
 pub struct TreeMap<K, V> {
@@ -355,22 +355,6 @@ impl <T: Ord> TreeSet<T>: Set<T> {
         }
         true
     }
-}
-
-impl <T: Ord> TreeSet<T> {
-    /// Create an empty TreeSet
-    static pure fn new() -> TreeSet<T> { TreeSet{map: TreeMap::new()} }
-
-    /// Visit all values in reverse order
-    pure fn each_reverse(&self, f: fn(&T) -> bool) {
-        self.map.each_key_reverse(f)
-    }
-
-    /// Get a lazy iterator over the values in the set.
-    /// Requires that it be frozen (immutable).
-    pure fn iter(&self) -> TreeSetIterator/&self<T> {
-        TreeSetIterator{iter: self.map.iter()}
-    }
 
     /// Visit the values (in-order) representing the difference
     pure fn difference(&self, other: &TreeSet<T>, f: fn(&T) -> bool) {
@@ -448,6 +432,22 @@ impl <T: Ord> TreeSet<T> {
             }
         }
     }
+}
+
+impl <T: Ord> TreeSet<T> {
+    /// Create an empty TreeSet
+    static pure fn new() -> TreeSet<T> { TreeSet{map: TreeMap::new()} }
+
+    /// Visit all values in reverse order
+    pure fn each_reverse(&self, f: fn(&T) -> bool) {
+        self.map.each_key_reverse(f)
+    }
+
+    /// Get a lazy iterator over the values in the set.
+    /// Requires that it be frozen (immutable).
+    pure fn iter(&self) -> TreeSetIterator/&self<T> {
+        TreeSetIterator{iter: self.map.iter()}
+    }
 
     /// Visit the values (in-order) representing the intersection
     pure fn intersection(&self, other: &TreeSet<T>, f: fn(&T) -> bool) {