Add a special case for erase(begin(), end()) to reset the control bytes. The motivation is to avoid potentially expanding the table unnecessarily later.

Note: I prefer doing this as a special case in erase(iterator, iterator) rather than special casing erase(iterator) for size==1 because IIUC that changes the time complexity of erase(iterator) from O(1) to O(N) and in pathological cases, it could change loops from O(N) to O(N^2).
PiperOrigin-RevId: 549661855
Change-Id: I8603324260f51a98809db32f840ff09f25cf2481

1 files changed, 8 insertions, 0 deletions

diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index 6cbf6dea..66621cf0 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -1093,6 +1093,14 @@ TEST(Table, EraseMaintainsValidIterator) {
   EXPECT_EQ(num_erase_calls, kNumElements);
 }
 
+TEST(Table, EraseBeginEnd) {
+  IntTable t;
+  for (int i = 0; i < 10; ++i) t.insert(i);
+  EXPECT_EQ(t.size(), 10);
+  t.erase(t.begin(), t.end());
+  EXPECT_EQ(t.size(), 0);
+}
+
 // Collect N bad keys by following algorithm:
 // 1. Create an empty table and reserve it to 2 * N.
 // 2. Insert N random elements.