send_map - fix size bug; add is_empty and test case for same

src/libcore/send_map.rs

@@ -229,6 +229,7 @@ mod linear {
                 self.insert_bucket(bucket);
                 idx = self.next_bucket(idx, len_buckets);
             }
+            self.size -= 1;
             ret true;
         }
     }
@@ -240,10 +241,14 @@ mod linear {
     }
 
     impl public_methods<K,V> for &const linear_map<K,V> {
-        fn size() -> uint {
+        fn len() -> uint {
             self.size
         }
 
+        fn is_empty() -> bool {
+            self.len() == 0
+        }
+
         fn contains_key(k: &K) -> bool {
             alt self.bucket_for_key(self.buckets, k) {
               found_entry(_) => {true}
@@ -377,6 +382,15 @@ mod test {
         assert m.get(&5) == 3;
     }
 
+    #[test]
+    fn empty() {
+        let mut m = ~linear::linear_map_with_capacity(uint_hash, uint_eq, 4);
+        assert m.insert(1, 2);
+        assert !m.is_empty();
+        assert m.remove(&1);
+        assert m.is_empty();
+    }
+
     #[test]
     fn iterate() {
         let mut m = linear::linear_map_with_capacity(uint_hash, uint_eq, 4);