Add missing overload to ordered_map::find (#5171)

* 🐛 add missing overload

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🎨 fix amalgamation

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix typo

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🚨 fix warning

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/ordered_map.hpp

@@ -340,6 +340,20 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         return Container::end();
     }
 
+    template<class KeyType, detail::enable_if_t<
+                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
+    const_iterator find(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return it;
+            }
+        }
+        return Container::end();
+    }
+
     std::pair<iterator, bool> insert( value_type&& value )
     {
         return emplace(value.first, std::move(value.second));

single_include/nlohmann/json.hpp

@@ -20468,6 +20468,20 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         return Container::end();
     }
 
+    template<class KeyType, detail::enable_if_t<
+                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
+    const_iterator find(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
+    {
+        for (auto it = this->begin(); it != this->end(); ++it)
+        {
+            if (m_compare(it->first, key))
+            {
+                return it;
+            }
+        }
+        return Container::end();
+    }
+
     std::pair<iterator, bool> insert( value_type&& value )
     {
         return emplace(value.first, std::move(value.second));

tests/src/unit-ordered_map.cpp

@@ -269,6 +269,11 @@ TEST_CASE("ordered_map")
         CHECK(com.find("vier") == com.end());
         CHECK(com.find(std::string("vier")) == com.end());
         CHECK(com.find(vier) == com.end());
+
+#ifdef JSON_HAS_CPP_17
+        CHECK(om.find(std::string_view("eins")) == om.begin());
+        CHECK(com.find(std::string_view("eins")) == com.begin());
+#endif
     }
 
     SECTION("insert")