stdlib: Added a treemap traversal function.

src/lib/treemap.rs

@@ -15,6 +15,7 @@ export treemap;
 export init;
 export insert;
 export find;
+export traverse;
 
 tag tree_node<@K, @V> {
     empty;
@@ -74,3 +75,25 @@ fn find<@K, @V>(m : &treemap<K, V>, k : &K) -> option<V> {
     }
   }
 }
+
+// Performs an in-order traversal
+fn traverse<@K, @V>(m : &treemap<K, V>, f : fn(&K, &V)) {
+  alt *m {
+    empty. { }
+    node(@k, @v, _, _) {
+      // copy v to make aliases work out
+      let v1 = v;
+      alt *m {
+        node(_, _, left, _) {
+          traverse(left, f);
+        }
+      }
+      f(k, v1);
+      alt *m {
+        node(_, _, _, right) {
+          traverse(right, f);
+        }
+      }
+    }
+  }
+}

src/test/stdtest/treemap.rs

@@ -40,3 +40,20 @@ fn find_not_found() {
     insert(m, 1, 2);
     assert(find(m, 2) == none);
 }
+
+#[test]
+fn traverse_in_order() {
+    let m = init();
+    insert(m, 3, ());
+    insert(m, 0, ());
+    insert(m, 4, ());
+    insert(m, 2, ());
+    insert(m, 1, ());
+
+    let n = 0;
+    fn t(n : &mutable int, k : &int, v : &()) {
+        assert(n == k);
+        n += 1;
+    }
+    traverse(m, bind t(n, _, _));
+}