From 3cae3fbb2b07d841cbc3fc65d14a5409b53ab4a4 Mon Sep 17 00:00:00 2001
From: skypjack <michele.caini@gmail.com>
Date: Fri, 9 Jan 2026 15:58:09 +0100
Subject: [PATCH] dense_map: operator==/operator<=>

---
 src/entt/container/dense_map.hpp | 58 ++++++++++----------------------
 1 file changed, 17 insertions(+), 41 deletions(-)

diff --git a/src/entt/container/dense_map.hpp b/src/entt/container/dense_map.hpp
index a1cfd4a44..a039c6e81 100644
--- a/src/entt/container/dense_map.hpp
+++ b/src/entt/container/dense_map.hpp
@@ -129,49 +129,25 @@ public:
         return operator[](0);
     }
 
-    template<typename Lhs, typename Rhs>
-    friend constexpr std::ptrdiff_t operator-(const dense_map_iterator<Lhs> &, const dense_map_iterator<Rhs> &) noexcept;
+    template<typename Other>
+    [[nodiscard]] constexpr std::ptrdiff_t operator-(const dense_map_iterator<Other> &other) const noexcept {
+        return it - other.it;
+    }
 
-    template<typename Lhs, typename Rhs>
-    friend constexpr bool operator==(const dense_map_iterator<Lhs> &, const dense_map_iterator<Rhs> &) noexcept;
+    template<typename Other>
+    [[nodiscard]] constexpr bool operator==(const dense_map_iterator<Other> &other) const noexcept {
+        return it == other.it;
+    }
 
-    template<typename Lhs, typename Rhs>
-    friend constexpr bool operator<(const dense_map_iterator<Lhs> &, const dense_map_iterator<Rhs> &) noexcept;
+    template<typename Other>
+    [[nodiscard]] constexpr auto operator<=>(const dense_map_iterator<Other> &other) const noexcept {
+        return it <=> other.it;
+    }
 
 private:
     It it;
 };
 
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr std::ptrdiff_t operator-(const dense_map_iterator<Lhs> &lhs, const dense_map_iterator<Rhs> &rhs) noexcept {
-    return lhs.it - rhs.it;
-}
-
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr bool operator==(const dense_map_iterator<Lhs> &lhs, const dense_map_iterator<Rhs> &rhs) noexcept {
-    return lhs.it == rhs.it;
-}
-
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr bool operator<(const dense_map_iterator<Lhs> &lhs, const dense_map_iterator<Rhs> &rhs) noexcept {
-    return lhs.it < rhs.it;
-}
-
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr bool operator>(const dense_map_iterator<Lhs> &lhs, const dense_map_iterator<Rhs> &rhs) noexcept {
-    return rhs < lhs;
-}
-
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr bool operator<=(const dense_map_iterator<Lhs> &lhs, const dense_map_iterator<Rhs> &rhs) noexcept {
-    return !(lhs > rhs);
-}
-
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr bool operator>=(const dense_map_iterator<Lhs> &lhs, const dense_map_iterator<Rhs> &rhs) noexcept {
-    return !(lhs < rhs);
-}
-
 template<typename It>
 class dense_map_local_iterator final {
     template<typename>
@@ -217,6 +193,11 @@ public:
         return {it[idx].element.first, it[idx].element.second};
     }
 
+    template<typename Other>
+    [[nodiscard]] constexpr bool operator==(const dense_map_local_iterator<Other> &other) const noexcept {
+        return offset == other.offset;
+    }
+
     [[nodiscard]] constexpr std::size_t index() const noexcept {
         return offset;
     }
@@ -226,11 +207,6 @@ private:
     std::size_t offset{dense_map_placeholder_position};
 };
 
-template<typename Lhs, typename Rhs>
-[[nodiscard]] constexpr bool operator==(const dense_map_local_iterator<Lhs> &lhs, const dense_map_local_iterator<Rhs> &rhs) noexcept {
-    return lhs.index() == rhs.index();
-}
-
 } // namespace internal
 /*! @endcond */