AK: Use OrderedHashMap in JsonObject

This changes JsonObject to use the new OrderedHashMap instead of an
extra vector for tracking the insertion order.

This also adds a default value for the KeyTraits template argument in
OrderedHashMap. Furthermore, it fixes two cases where code iterating
over a JsonObject relied on the value argument being copied before
invoking the callback.

AK/Forward.h

@@ -78,7 +78,7 @@ using OrderedHashTable = HashTable<T, TraitsForT, true>;
 template<typename K, typename V, typename KeyTraits = Traits<K>, bool IsOrdered = false>
 class HashMap;
 
-template<typename K, typename V, typename KeyTraits>
+template<typename K, typename V, typename KeyTraits = Traits<K>>
 using OrderedHashMap = HashMap<K, V, KeyTraits, true>;
 
 template<typename T>

AK/JsonObject.h

@@ -21,32 +21,26 @@ public:
     ~JsonObject() = default;
 
     JsonObject(JsonObject const& other)
-        : m_order(other.m_order)
+        : m_members(other.m_members)
-        , m_members(other.m_members)
     {
     }
 
     JsonObject(JsonObject&& other)
-        : m_order(move(other.m_order))
+        : m_members(move(other.m_members))
-        , m_members(move(other.m_members))
     {
     }
 
     JsonObject& operator=(JsonObject const& other)
     {
-        if (this != &other) {
+        if (this != &other)
             m_members = other.m_members;
-            m_order = other.m_order;
-        }
         return *this;
     }
 
     JsonObject& operator=(JsonObject&& other)
     {
-        if (this != &other) {
+        if (this != &other)
             m_members = move(other.m_members);
-            m_order = move(other.m_order);
-        }
         return *this;
     }
 
@@ -80,27 +74,19 @@ public:
 
     void set(String const& key, JsonValue value)
     {
-        if (m_members.set(key, move(value)) == HashSetResult::ReplacedExistingEntry)
+        m_members.set(key, move(value));
-            m_order.remove(m_order.find_first_index(key).value());
-        m_order.append(key);
     }
 
     template<typename Callback>
     void for_each_member(Callback callback) const
     {
-        for (size_t i = 0; i < m_order.size(); ++i) {
+        for (auto& member : m_members)
-            auto property = m_order[i];
+            callback(member.key, member.value);
-            callback(property, m_members.get(property).value());
-        }
     }
 
     bool remove(String const& key)
     {
-        if (m_members.remove(key)) {
+        return m_members.remove(key);
-            m_order.remove(m_order.find_first_index(key).value());
-            return true;
-        }
-        return false;
     }
 
     template<typename Builder>
@@ -112,8 +98,7 @@ public:
     String to_string() const { return serialized<StringBuilder>(); }
 
 private:
-    Vector<String> m_order;
+    OrderedHashMap<String, JsonValue> m_members;
-    HashMap<String, JsonValue> m_members;
 };
 
 template<typename Builder>

Userland/Applications/Spreadsheet/Spreadsheet.cpp

@@ -376,7 +376,7 @@ RefPtr<Sheet> Sheet::from_json(const JsonObject& object, Workbook& workbook)
             format.background_color = Color::from_string(value.as_string());
     };
 
-    cells.for_each_member([&](auto& name, JsonValue& value) {
+    cells.for_each_member([&](auto& name, JsonValue const& value) {
         auto position_option = sheet->parse_cell_name(name);
         if (!position_option.has_value())
             return IterationDecision::Continue;