meta_[sequence|associative]_container: iterator review

src/entt/meta/meta.hpp

@@ -1495,7 +1495,7 @@ public:
      * @param iter The actual iterator with which to build the meta iterator.
      */
     template<typename It>
-    meta_iterator(It iter)
+    explicit meta_iterator(It iter)
         : vtable{&basic_vtable<It>},
           handle{std::move(iter)} {}
 
@@ -1510,24 +1510,6 @@ public:
         return ++(*this), orig;
     }
 
-    /**
-     * @brief Checks if two iterators refer to the same element.
-     * @param other The iterator with which to compare.
-     * @return True if the iterators refer to the same element, false otherwise.
-     */
-    [[nodiscard]] bool operator==(const meta_iterator &other) const ENTT_NOEXCEPT {
-        return handle == other.handle;
-    }
-
-    /**
-     * @brief Checks if two iterators refer to the same element.
-     * @param other The iterator with which to compare.
-     * @return False if the iterators refer to the same element, true otherwise.
-     */
-    [[nodiscard]] bool operator!=(const meta_iterator &other) const ENTT_NOEXCEPT {
-        return !(*this == other);
-    }
-
     /**
      * @brief Indirection operator for accessing the pointed opaque object.
      * @return The element to which the iterator points.
@@ -1567,6 +1549,26 @@ private:
     any handle{};
 };
 
+/**
+ * @brief Checks if two iterators refer to the same element.
+ * @param lhs An iterator to compare.
+ * @param rhs An iterator with which to compare.
+ * @return True if the iterators refer to the same element, false otherwise.
+ */
+[[nodiscard]] inline bool operator==(const typename meta_sequence_container::iterator &lhs, const typename meta_sequence_container::iterator &rhs) ENTT_NOEXCEPT {
+    return lhs.base() == rhs.base();
+}
+
+/**
+ * @brief Checks if two iterators refer to the same element.
+ * @param lhs An iterator to compare.
+ * @param rhs An iterator with which to compare.
+ * @return False if the iterators refer to the same element, true otherwise.
+ */
+[[nodiscard]] inline bool operator!=(const typename meta_sequence_container::iterator &lhs, const typename meta_sequence_container::iterator &rhs) ENTT_NOEXCEPT {
+    return !(lhs == rhs);
+}
+
 /**
  * @brief Returns the meta value type of a container.
  * @return The meta value type of the container.
@@ -1717,24 +1719,6 @@ public:
         return ++(*this), orig;
     }
 
-    /**
-     * @brief Checks if two iterators refer to the same element.
-     * @param other The iterator with which to compare.
-     * @return True if the iterators refer to the same element, false otherwise.
-     */
-    [[nodiscard]] bool operator==(const meta_iterator &other) const ENTT_NOEXCEPT {
-        return handle == other.handle;
-    }
-
-    /**
-     * @brief Checks if two iterators refer to the same element.
-     * @param other The iterator with which to compare.
-     * @return False if the iterators refer to the same element, true otherwise.
-     */
-    [[nodiscard]] bool operator!=(const meta_iterator &other) const ENTT_NOEXCEPT {
-        return !(*this == other);
-    }
-
     /**
      * @brief Indirection operator for accessing the pointed opaque object.
      * @return The element to which the iterator points.
@@ -1761,11 +1745,39 @@ public:
         return static_cast<bool>(handle);
     }
 
+    /**
+     * @brief Returns the underlying iterator.
+     * @return The underlying iterator.
+     */
+    any base() const ENTT_NOEXCEPT {
+        return handle.as_ref();
+    }
+
 private:
     vtable_type *vtable{};
     any handle{};
 };
 
+/**
+ * @brief Checks if two iterators refer to the same element.
+ * @param lhs An iterator to compare.
+ * @param rhs An iterator with which to compare.
+ * @return True if the iterators refer to the same element, false otherwise.
+ */
+[[nodiscard]] inline bool operator==(const typename meta_associative_container::iterator &lhs, const typename meta_associative_container::iterator &rhs) ENTT_NOEXCEPT {
+    return lhs.base() == rhs.base();
+}
+
+/**
+ * @brief Checks if two iterators refer to the same element.
+ * @param lhs An iterator to compare.
+ * @param rhs An iterator with which to compare.
+ * @return False if the iterators refer to the same element, true otherwise.
+ */
+[[nodiscard]] inline bool operator!=(const typename meta_associative_container::iterator &lhs, const typename meta_associative_container::iterator &rhs) ENTT_NOEXCEPT {
+    return !(lhs == rhs);
+}
+
 /**
  * @brief Returns true if a container is also key-only, false otherwise.
  * @return True if the associative container is also key-only, false otherwise.