insert_or_assign for std::sets

headers/meta.hpp/meta_base.hpp

@@ -12,6 +12,7 @@
 #include "meta_base/cvref_traits.hpp"
 #include "meta_base/fixed_function.hpp"
 #include "meta_base/hash_combiner.hpp"
+#include "meta_base/insert_or_assign.hpp"
 #include "meta_base/is_in_place_type.hpp"
 #include "meta_base/memory_buffer.hpp"
 #include "meta_base/noncopyable.hpp"

headers/meta.hpp/meta_base/insert_or_assign.hpp

@@ -0,0 +1,44 @@
+/*******************************************************************************
+ * This file is part of the "https://github.com/blackmatov/meta.hpp"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2021-2023, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#pragma once
+
+#include "base.hpp"
+
+namespace meta_hpp::detail
+{
+    template < typename Key, typename Compare, typename Allocator >
+    typename std::set<Key, Compare, Allocator>::iterator
+    insert_or_assign(std::set<Key, Compare, Allocator>& set,
+        typename std::set<Key, Compare, Allocator>::value_type&& value)
+    {
+        auto&& [position, inserted] = set.insert(std::move(value));
+
+        if ( inserted ) {
+            return position;
+        }
+
+        auto node = set.extract(position++);
+        node.value() = std::move(value);
+        return set.insert(position, std::move(node));
+    }
+
+    template < typename Key, typename Compare, typename Allocator >
+    typename std::set<Key, Compare, Allocator>::iterator
+    insert_or_assign(std::set<Key, Compare, Allocator>& set,
+        const typename std::set<Key, Compare, Allocator>::value_type& value)
+    {
+        auto&& [position, inserted] = set.insert(value);
+
+        if ( inserted ) {
+            return position;
+        }
+
+        auto node = set.extract(position++);
+        node.value() = value;
+        return set.insert(position, std::move(node));
+    }
+}