From d1e13d51281b6caf008869845792d77f72175a11 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Wed, 2 Aug 2017 22:12:41 +0200
Subject: [PATCH] :tada: first draft for #661

---
 src/json.hpp | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/json.hpp b/src/json.hpp
index c22cce4f9..5253a613b 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -12066,6 +12066,31 @@ class basic_json
         m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator);
     }
 
+    void update(const_reference j)
+    {
+        // implicitly convert null value to an empty object
+        if (is_null())
+        {
+            m_type = value_t::object;
+            m_value.object = create<object_t>();
+            assert_invariant();
+        }
+
+        if (JSON_UNLIKELY(not is_object()))
+        {
+            JSON_THROW(type_error::create(305, "cannot use merge with " + type_name()));
+        }
+        if (JSON_UNLIKELY(not j.is_object()))
+        {
+            JSON_THROW(type_error::create(305, "cannot use merge with " + j.type_name()));
+        }
+
+        for (auto it = j.begin(); it != j.end(); ++it)
+        {
+            m_value.object->emplace(it.key(), it.value());
+        }
+    }
+
     /*!
     @brief exchanges the values