1 files changed, 24 insertions, 0 deletions
diff --git a/src/rocksdb/util/set_comparator.h b/src/rocksdb/util/set_comparator.h
new file mode 100644
index 000000000..e0e64436a
--- /dev/null
+++ b/src/rocksdb/util/set_comparator.h
@@ -0,0 +1,24 @@
+// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include "rocksdb/comparator.h"
+
+namespace ROCKSDB_NAMESPACE {
+// A comparator to be used in std::set
+struct SetComparator {
+  explicit SetComparator() : user_comparator_(BytewiseComparator()) {}
+  explicit SetComparator(const Comparator* user_comparator)
+      : user_comparator_(user_comparator ? user_comparator
+                                         : BytewiseComparator()) {}
+  bool operator()(const Slice& lhs, const Slice& rhs) const {
+    return user_comparator_->Compare(lhs, rhs) < 0;
+  }
+
+ private:
+  const Comparator* user_comparator_;
+};
+}  // namespace ROCKSDB_NAMESPACE