QFlatMap: add insert_or_assign

This does exactly what insert() on Qt associative containers does, but
allows to express the intent of using the STL-incompatible Qt insert()
semantics, in an STL-compatible way, instead of leaving the reader of
the code wondering what semantics are expected.

This is part of a very-long-term goal of fixing Qt associative
container's insert() behavior, in which QFlatMap, being an affected,
but private-API type, is used for proof-of-concept purposes.

Task-number: QTBUG-99651
Pick-to: 6.3 6.2
Change-Id: I69010285438259918aef659d3235180c1b5be696
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/corelib/tools/qflatmap_p.h b/src/corelib/tools/qflatmap_p.h
index 3b847fc63a..fd08676ae3 100644
--- a/src/corelib/tools/qflatmap_p.h
+++ b/src/corelib/tools/qflatmap_p.h
@@ -750,6 +750,24 @@ public:
         }
     }
 
+    template <typename M>
+    std::pair<iterator, bool> insert_or_assign(const Key &key, M &&obj)
+    {
+        auto r = try_emplace(key, std::forward<M>(obj));
+        if (!r.second)
+            *toValuesIterator(r.first) = std::forward<M>(obj);
+        return r;
+    }
+
+    template <typename M>
+    std::pair<iterator, bool> insert_or_assign(Key &&key, M &&obj)
+    {
+        auto r = try_emplace(std::move(key), std::forward<M>(obj));
+        if (!r.second)
+            *toValuesIterator(r.first) = std::forward<M>(obj);
+        return r;
+    }
+
     template <class InputIt, is_compatible_iterator<InputIt> = nullptr>
     void insert(InputIt first, InputIt last)
     {