Added Tombstones

.gitignore

@@ -0,0 +1,13 @@
+# Compiled files
+*.o
+*.so
+*.rlib
+*.dll
+
+# Executables
+*.exe
+
+# Generated by Cargo
+/target/
+Cargo.lock
+

Cargo.toml

@@ -10,8 +10,6 @@ description = "A hash table with consistent order and fast iteration."
 [lib]
 bench = false
 
-[dependencies]
-
 [dev-dependencies]
 itertools = "0.5.1"
 rand = "0.3"

benches/bench.rs

@@ -610,3 +610,36 @@ fn retain_many_ordermap_100_000(b: &mut Bencher) {
         map
     });
 }
+
+#[bench]
+fn remove_index_tombstones_many_ordermap_100_000(b: &mut Bencher) {
+    let mut map = OMAP_100K.clone();
+    map.retain(|k, _| *k % 7 == 0);
+
+    b.iter(|| {
+        let mut map = map.clone();
+        map.remove_index_tombstones()
+    });
+}
+
+#[bench]
+fn remove_index_tombstones_half_ordermap_100_000(b: &mut Bencher) {
+    let mut map = OMAP_100K.clone();
+    map.retain(|k, _| *k % 2 == 0);
+
+    b.iter(|| {
+        let mut map = map.clone();
+        map.remove_index_tombstones()
+    });
+}
+
+#[bench]
+fn remove_index_tombstones_some_ordermap_100_000(b: &mut Bencher) {
+    let mut map = OMAP_100K.clone();
+    map.retain(|k, _| *k % 100 == 0);
+
+    b.iter(|| {
+        let mut map = map.clone();
+        map.remove_index_tombstones()
+    });
+}