From 8f1fa0d1307d7a60844de0ca33628e0c6997468e Mon Sep 17 00:00:00 2001
From: Jon Bailey <jonathan.bailey1@ibm.com>
Date: Mon, 12 May 2025 21:19:48 +0100
Subject: [PATCH] common: Add iterator traits to mini_flat_map and bitset_set
 iterator

Add iterator traits to mini_flat_map and bitset_set iterator to allow std algorithms to be able to perform operations using the mini_flat_map iterator

Signed-off-by: Jon Bailey <jonathan.bailey1@ibm.com>
---
 src/common/bitset_set.h    |  4 ++++
 src/common/mini_flat_map.h | 18 ++++++++++++------
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/common/bitset_set.h b/src/common/bitset_set.h
index d6d02144959..182d635b559 100644
--- a/src/common/bitset_set.h
+++ b/src/common/bitset_set.h
@@ -39,7 +39,11 @@ class bitset_set {
     KeyT pos;
 
    public:
+    using value_type = const KeyT;
     using difference_type = std::int64_t;
+    using pointer = const value_type *;
+    using reference = const value_type &;
+    using iterator_category = std::forward_iterator_tag;
 
     const_iterator() : set(nullptr), pos(0) {
     }
diff --git a/src/common/mini_flat_map.h b/src/common/mini_flat_map.h
index 46abda51387..6d1cea34c15 100644
--- a/src/common/mini_flat_map.h
+++ b/src/common/mini_flat_map.h
@@ -50,14 +50,22 @@ class mini_flat_map {
   template<bool is_const>
   class _iterator {
     friend class mini_flat_map;
-    using mini_flat_map_p = std::conditional_t<is_const,
-                                               const mini_flat_map *,
-                                               mini_flat_map *>;
+
+   public:
+    // types required by std::iterator_traits
     using value_type = std::conditional_t<is_const,
                                           const std::pair<const KeyT &,
                                                           const ValueT &>,
                                           std::pair<const KeyT &, ValueT &>>;
-
+    using difference_type = std::ptrdiff_t;
+    using pointer = const value_type *;
+    using reference = const value_type &;
+    using iterator_category = std::forward_iterator_tag;
+
+   private:
+   using mini_flat_map_p = std::conditional_t<is_const,
+                                              const mini_flat_map *,
+                                              mini_flat_map *>;
     mini_flat_map_p map;
     std::optional<value_type> value;
     KeyT key;
@@ -73,8 +81,6 @@ class mini_flat_map {
     }
 
    public:
-    using difference_type = std::ptrdiff_t;
-
     _iterator(mini_flat_map_p map) : map(map), key(0) {
       progress();
     }
-- 
2.47.3