StateEvent; EventContent::SimpleContent; event types refactoring

* StateEvent<> is a new class template for all state events. It provides a uniform interface to the state content, as well as a means to serialize the content back to JSON. In addition, StateEvent now parses the "prev_content" JSON object, so one can refer to the previous state now (a notable step to proper reflection of state changes in the displayed timeline in clients).
* EventContent::SimpleContent, together with StateEvent<>, forms a generalisation for simple state events, such as room name, topic, aliases etc. that boil down to a single key-value pair. DECLARE_SIMPLE_STATE_EVENT is a macro defined to streamline creation of events based on SimpleContent, providing API back-compatibility for events defined so far. As a result, a very concise simplestateevents.h replaces all those room*event.* files.
* Event/RoomEvent::fromJson() code is squeezed down to plain type lists passed to makeIfMatches() "chained factory" function template. TypeId is mandatory for an event type to be included into that factory.
* Event::toTimestamp() and Event::toStringList are completely superseded by respective fromJson<>() converters.

15 files changed, 148 insertions, 388 deletions

diff --git a/events/encryptedevent.cpp b/events/encryptedevent.cpp
deleted file mode 100644
index 90e77c36..00000000
--- a/events/encryptedevent.cpp
+++ /dev/null
@@ -1,5 +0,0 @@
-//
-// Created by rusakov on 26/09/2017.
-//
-
-#include "encryptedevent.h"
diff --git a/events/encryptedevent.h b/events/encryptedevent.h
deleted file mode 100644
index 9db462e1..00000000
--- a/events/encryptedevent.h
+++ /dev/null
@@ -1,39 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2017 Kitsune Ral <kitsune-ral@users.sf.net>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-#pragma once
-
-#include "event.h"
-
-namespace QMatrixClient
-{
-    class EncryptionEvent : public RoomEvent
-    {
-        public:
-            explicit EncryptionEvent(const QJsonObject& obj)
-                : RoomEvent(Type::RoomEncryption, obj)
-                , _algorithm(contentJson()["algorithm"].toString())
-            { }
-
-            QString algorithm() const { return _algorithm; }
-
-        private:
-            QString _algorithm;
-    };
-}  // namespace QMatrixClient
-
diff --git a/events/event.cpp b/events/event.cpp
index 9963a0ef..44b742c1 100644
--- a/events/event.cpp
+++ b/events/event.cpp
@@ -19,15 +19,11 @@
 #include "event.h"
 
 #include "roommessageevent.h"
-#include "roomnameevent.h"
-#include "roomaliasesevent.h"
-#include "roomcanonicalaliasevent.h"
+#include "simplestateevents.h"
 #include "roommemberevent.h"
-#include "roomtopicevent.h"
 #include "roomavatarevent.h"
 #include "typingevent.h"
 #include "receiptevent.h"
-#include "encryptedevent.h"
 #include "logging.h"
 
 #include <QtCore/QJsonDocument>
@@ -54,32 +50,24 @@ QJsonObject Event::originalJsonObject() const
     return _originalJson;
 }
 
-QDateTime Event::toTimestamp(const QJsonValue& v)
+const QJsonObject Event::contentJson() const
 {
-    Q_ASSERT(v.isDouble() || v.isNull() || v.isUndefined());
-    return QDateTime::fromMSecsSinceEpoch(
-            static_cast<long long int>(v.toDouble()), Qt::UTC);
+    return _originalJson["content"].toObject();
 }
 
-QStringList Event::toStringList(const QJsonValue& v)
+template <typename BaseEventT>
+inline BaseEventT* makeIfMatches(const QJsonObject&, const QString&)
 {
-    Q_ASSERT(v.isArray() || v.isNull() || v.isUndefined());
-
-    QStringList l;
-    for( const QJsonValue& e : v.toArray() )
-        l.push_back(e.toString());
-    return l;
+    return nullptr;
 }
 
-const QJsonObject Event::contentJson() const
+template <typename BaseEventT, typename EventT, typename... EventTs>
+inline BaseEventT* makeIfMatches(const QJsonObject& o, const QString& selector)
 {
-    return _originalJson["content"].toObject();
-}
+    if (selector == EventT::TypeId)
+        return new EventT(o);
 
-template <typename EventT>
-EventT* make(const QJsonObject& o)
-{
-    return new EventT(o);
+    return makeIfMatches<BaseEventT, EventTs...>(o, selector);
 }
 
 Event* Event::fromJson(const QJsonObject& obj)
@@ -88,17 +76,14 @@ Event* Event::fromJson(const QJsonObject& obj)
     if (auto e = RoomEvent::fromJson(obj))
         return e;
 
-    return dispatch<Event*>(obj).to(obj["type"].toString(),
-            "m.typing", make<TypingEvent>,
-            "m.receipt", make<ReceiptEvent>,
-            /* Insert new event types (except room events) BEFORE this line */
-            nullptr
-            );
+    return makeIfMatches<Event,
+        TypingEvent, ReceiptEvent>(obj, obj["type"].toString());
 }
 
 RoomEvent::RoomEvent(Type type, const QJsonObject& rep)
     : Event(type, rep), _id(rep["event_id"].toString())
-    , _serverTimestamp(toTimestamp(rep["origin_server_ts"]))
+    , _serverTimestamp(
+          QMatrixClient::fromJson<QDateTime>(rep["origin_server_ts"]))
     , _roomId(rep["room_id"].toString())
     , _senderId(rep["sender"].toString())
     , _txnId(rep["unsigned"].toObject().value("transactionId").toString())
@@ -130,16 +115,8 @@ void RoomEvent::addId(const QString& id)
 
 RoomEvent* RoomEvent::fromJson(const QJsonObject& obj)
 {
-    return dispatch<RoomEvent*>(obj).to(obj["type"].toString(),
-            "m.room.message", make<RoomMessageEvent>,
-            "m.room.name", make<RoomNameEvent>,
-            "m.room.aliases", make<RoomAliasesEvent>,
-            "m.room.canonical_alias", make<RoomCanonicalAliasEvent>,
-            "m.room.member", make<RoomMemberEvent>,
-            "m.room.topic", make<RoomTopicEvent>,
-            "m.room.avatar", make<RoomAvatarEvent>,
-            "m.room.encryption", make<EncryptionEvent>,
-            /* Insert new ROOM event types BEFORE this line */
-            nullptr
-        );
+    return makeIfMatches<RoomEvent,
+        RoomMessageEvent, RoomNameEvent, RoomAliasesEvent,
+        RoomCanonicalAliasEvent, RoomMemberEvent, RoomTopicEvent,
+        RoomAvatarEvent, EncryptionEvent>(obj, obj["type"].toString());
 }
diff --git a/events/event.h b/events/event.h
index c151ac0e..020ef54b 100644
--- a/events/event.h
+++ b/events/event.h
@@ -56,9 +56,6 @@ namespace QMatrixClient
             static Event* fromJson(const QJsonObject& obj);
 
         protected:
-            static QDateTime toTimestamp(const QJsonValue& v);
-            static QStringList toStringList(const QJsonValue& v);
-
             const QJsonObject contentJson() const;
 
         private:
@@ -74,25 +71,20 @@ namespace QMatrixClient
     using EventsBatch = std::vector<EventT*>;
     using Events = EventsBatch<Event>;
 
-    template <typename BaseEventT>
-    BaseEventT* makeEvent(const QJsonObject& obj)
-    {
-        if (auto e = BaseEventT::fromJson(obj))
-            return e;
-
-        return new BaseEventT(EventType::Unknown, obj);
-    }
-
     template <typename BaseEventT = Event,
               typename BatchT = EventsBatch<BaseEventT> >
-    BatchT makeEvents(const QJsonArray& objs)
+    inline BatchT makeEvents(const QJsonArray& objs)
     {
         BatchT evs;
         // The below line accommodates the difference in size types of
         // STL and Qt containers.
         evs.reserve(static_cast<typename BatchT::size_type>(objs.size()));
-        for (auto obj: objs)
-            evs.push_back(makeEvent<BaseEventT>(obj.toObject()));
+        for (auto objValue: objs)
+        {
+            const auto o = objValue.toObject();
+            auto e = BaseEventT::fromJson(o);
+            evs.push_back(e ? e : new BaseEventT(EventType::Unknown, o));
+        }
         return evs;
     }
 
@@ -147,6 +139,37 @@ namespace QMatrixClient
             QString _txnId;
     };
     using RoomEvents = EventsBatch<RoomEvent>;
+
+    template <typename ContentT>
+    class StateEvent: public RoomEvent
+    {
+        public:
+            using content_type = ContentT;
+
+            template <typename... ContentParamTs>
+            explicit StateEvent(Type type, const QJsonObject& obj,
+                                ContentParamTs&&... contentParams)
+                : RoomEvent(type, obj)
+                , _content(contentJson(),
+                           std::forward<ContentParamTs>(contentParams)...)
+                , _prev(new ContentT(obj["prev_content"].toObject(),
+                            std::forward<ContentParamTs>(contentParams)...))
+            { }
+            template <typename... ContentParamTs>
+            explicit StateEvent(Type type, ContentParamTs&&... contentParams)
+                : RoomEvent(type)
+                , _content(std::forward<ContentParamTs>(contentParams)...)
+            { }
+
+            QJsonObject toJson() const { return _content.toJson(); }
+
+            ContentT content() const { return _content; }
+            ContentT* prev_content() const { return _prev.data(); }
+
+        protected:
+            ContentT _content;
+            QScopedPointer<ContentT> _prev;
+    };
 }  // namespace QMatrixClient
 Q_DECLARE_OPAQUE_POINTER(QMatrixClient::Event*)
 Q_DECLARE_METATYPE(QMatrixClient::Event*)
diff --git a/events/eventcontent.h b/events/eventcontent.h
index f9cdaf11..60437995 100644
--- a/events/eventcontent.h
+++ b/events/eventcontent.h
@@ -21,6 +21,8 @@
 // This file contains generic event content definitions, applicable to room
 // message events as well as other events (e.g., avatars).
 
+#include "converters.h"
+
 #include <QtCore/QJsonObject>
 #include <QtCore/QMimeType>
 #include <QtCore/QUrl>
@@ -60,6 +62,35 @@ namespace QMatrixClient
                 virtual QMimeType type() const = 0;
         };
 
+        template <typename T = QString>
+        class SimpleContent: public Base
+        {
+            public:
+                using value_type = T;
+
+                // The constructor is templated to enable perfect forwarding
+                template <typename TT>
+                SimpleContent(QString keyName, TT&& value)
+                    : value(std::forward<TT>(value)), key(std::move(keyName))
+                { }
+                SimpleContent(const QJsonObject& json, QString keyName)
+                    : value(QMatrixClient::fromJson<T>(json[keyName]))
+                    , key(std::move(keyName))
+                { }
+
+                T value;
+
+            protected:
+                QString key;
+
+            private:
+                void fillJson(QJsonObject* json) const override
+                {
+                    Q_ASSERT(json);
+                    json->insert(key, QMatrixClient::toJson(value));
+                }
+        };
+
         /**
          * A base class for content types that have an "info" object in their
          * JSON representation
diff --git a/events/roomaliasesevent.cpp b/events/roomaliasesevent.cpp
deleted file mode 100644
index 344b4367..00000000
--- a/events/roomaliasesevent.cpp
+++ /dev/null
@@ -1,43 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2015 Felix Rohrbach <kde@fxrh.de>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-// Example of a RoomAliases Event:
-//
-// {
-//     "age":3758857346,
-//     "content":{
-//         "aliases":["#freenode_#testest376:matrix.org"]
-//     },
-//     "event_id":"$1439989428122drFjY:matrix.org",
-//     "origin_server_ts":1439989428910,
-//     "replaces_state":"$143613875199223YYPrN:matrix.org",
-//     "room_id":"!UoqtanuuSGTMvNRfDG:matrix.org",
-//     "state_key":"matrix.org",
-//     "type":"m.room.aliases",
-//     "user_id":"@appservice-irc:matrix.org"
-// }
-
-#include "roomaliasesevent.h"
-
-using namespace QMatrixClient;
-
-RoomAliasesEvent::RoomAliasesEvent(const QJsonObject& obj)
-    : RoomEvent(Type::RoomAliases, obj)
-    , _aliases(toStringList(contentJson()["aliases"]))
-{ }
-
diff --git a/events/roomaliasesevent.h b/events/roomaliasesevent.h
deleted file mode 100644
index efafcb30..00000000
--- a/events/roomaliasesevent.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2015 Felix Rohrbach <kde@fxrh.de>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-#pragma once
-
-#include "event.h"
-
-#include <QtCore/QStringList>
-
-namespace QMatrixClient
-{
-    class RoomAliasesEvent: public RoomEvent
-    {
-        public:
-            explicit RoomAliasesEvent(const QJsonObject& obj);
-
-            QStringList aliases() const { return _aliases; }
-
-        private:
-            QStringList _aliases;
-    };
-}  // namespace QMatrixClient
diff --git a/events/roomavatarevent.h b/events/roomavatarevent.h
index 411de4e8..ccfe8fbf 100644
--- a/events/roomavatarevent.h
+++ b/events/roomavatarevent.h
@@ -26,28 +26,18 @@
 
 namespace QMatrixClient
 {
-    class RoomAvatarEvent: public RoomEvent
+    class RoomAvatarEvent: public StateEvent<EventContent::ImageContent>
     {
+            // It's a bit of an overkill to use a full-fledged ImageContent
+            // because in reality m.room.avatar usually only has a single URL,
+            // without a thumbnail. But The Spec says there be thumbnails, and
+            // we follow The Spec.
         public:
-            explicit RoomAvatarEvent(EventContent::ImageContent avatar)
-                : RoomEvent(Type::RoomAvatar), _avatar(std::move(avatar))
-            { }
             explicit RoomAvatarEvent(const QJsonObject& obj)
-                : RoomEvent(Type::RoomAvatar, obj), _avatar(contentJson())
+                : StateEvent(Type::RoomAvatar, obj)
             { }
 
-            const EventContent::ImageContent& content() const { return _avatar; }
-
-            QJsonObject toJson() const { return _avatar.toJson(); }
-
             static constexpr const char* TypeId = "m.room.avatar";
-
-        private:
-            // It's a bit of an overkill to use a full-fledged ImageContent
-            // because in reality m.room.avatar usually only has a single URL,
-            // without a thumbnail. But The Spec says there be thumbnails, and
-            // we follow The Spec.
-            EventContent::ImageContent _avatar;
     };
 
 }  // namespace QMatrixClient
diff --git a/events/roomcanonicalaliasevent.cpp b/events/roomcanonicalaliasevent.cpp
deleted file mode 100644
index 6884bc15..00000000
--- a/events/roomcanonicalaliasevent.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2016 Felix Rohrbach <kde@fxrh.de>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-#include "roomcanonicalaliasevent.h"
-
-using namespace QMatrixClient;
diff --git a/events/roomcanonicalaliasevent.h b/events/roomcanonicalaliasevent.h
deleted file mode 100644
index 72620d74..00000000
--- a/events/roomcanonicalaliasevent.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2016 Felix Rohrbach <kde@fxrh.de>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-#pragma once
-
-#include "event.h"
-
-namespace QMatrixClient
-{
-    class RoomCanonicalAliasEvent : public RoomEvent
-    {
-        public:
-            explicit RoomCanonicalAliasEvent(const QJsonObject& obj)
-                : RoomEvent(Type::RoomCanonicalAlias, obj)
-                , _canonicalAlias(contentJson()["alias"].toString())
-            { }
-
-            QString alias() const { return _canonicalAlias; }
-
-        private:
-            QString _canonicalAlias;
-    };
-}  // namespace QMatrixClient
diff --git a/events/roomnameevent.cpp b/events/roomnameevent.cpp
deleted file mode 100644
index c202d17a..00000000
--- a/events/roomnameevent.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-/******************************************************************************

- * Copyright (C) 2015 Kitsune Ral <kitsune-ral@users.sf.net>

- *

- * This library is free software; you can redistribute it and/or

- * modify it under the terms of the GNU Lesser General Public

- * License as published by the Free Software Foundation; either

- * version 2.1 of the License, or (at your option) any later version.

- *

- * This library is distributed in the hope that it will be useful,

- * but WITHOUT ANY WARRANTY; without even the implied warranty of

- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

- * Lesser General Public License for more details.

- *

- * You should have received a copy of the GNU Lesser General Public

- * License along with this library; if not, write to the Free Software

- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

- */

-

-#include "roomnameevent.h"

-

-using namespace QMatrixClient;

-

diff --git a/events/roomnameevent.h b/events/roomnameevent.h
deleted file mode 100644
index bb823933..00000000
--- a/events/roomnameevent.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/******************************************************************************

- * Copyright (C) 2015 Kitsune Ral <kitsune-ral@users.sf.net>

- *

- * This library is free software; you can redistribute it and/or

- * modify it under the terms of the GNU Lesser General Public

- * License as published by the Free Software Foundation; either

- * version 2.1 of the License, or (at your option) any later version.

- *

- * This library is distributed in the hope that it will be useful,

- * but WITHOUT ANY WARRANTY; without even the implied warranty of

- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

- * Lesser General Public License for more details.

- *

- * You should have received a copy of the GNU Lesser General Public

- * License along with this library; if not, write to the Free Software

- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

- */

-

-#pragma once

-

-#include "event.h"

-

-namespace QMatrixClient

-{

-    class RoomNameEvent : public RoomEvent

-    {

-        public:

-            explicit RoomNameEvent(const QJsonObject& obj)

-                : RoomEvent(Type::RoomName, obj)

-                , _name(contentJson()["name"].toString())

-            { }

-

-            QString name() const { return _name; }

-

-        private:

-            QString _name{};

-    };

-} // namespace QMatrixClient

diff --git a/events/roomtopicevent.cpp b/events/roomtopicevent.cpp
deleted file mode 100644
index 26677e78..00000000
--- a/events/roomtopicevent.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2015 Felix Rohrbach <kde@fxrh.de>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-#include "roomtopicevent.h"
-
-using namespace QMatrixClient;
-
diff --git a/events/roomtopicevent.h b/events/roomtopicevent.h
deleted file mode 100644
index 95ad0e04..00000000
--- a/events/roomtopicevent.h
+++ /dev/null
@@ -1,50 +0,0 @@
-/******************************************************************************
- * Copyright (C) 2015 Felix Rohrbach <kde@fxrh.de>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-#pragma once
-
-#include "event.h"
-
-namespace QMatrixClient
-{
-    class RoomTopicEvent: public RoomEvent
-    {
-        public:
-            explicit RoomTopicEvent(const QString& topic)
-                : RoomEvent(Type::RoomTopic), _topic(topic)
-            { }
-            explicit RoomTopicEvent(const QJsonObject& obj)
-                : RoomEvent(Type::RoomTopic, obj)
-                , _topic(contentJson()["topic"].toString())
-            { }
-
-            QString topic() const { return _topic; }
-
-            QJsonObject toJson() const
-            {
-                QJsonObject obj;
-                obj.insert("topic", _topic);
-                return obj;
-            }
-
-            static constexpr const char* TypeId = "m.room.topic";
-
-        private:
-            QString _topic;
-    };
-}  // namespace QMatrixClient
diff --git a/events/simplestateevents.h b/events/simplestateevents.h
new file mode 100644
index 00000000..d5841bdc
--- /dev/null
+++ b/events/simplestateevents.h
@@ -0,0 +1,54 @@
+/******************************************************************************
+ * Copyright (C) 2017 Kitsune Ral <kitsune-ral@users.sf.net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#pragma once
+
+#include "event.h"
+
+#include "eventcontent.h"
+
+namespace QMatrixClient
+{
+#define DECLARE_SIMPLE_STATE_EVENT(_Name, _TypeId, _EnumType, _ContentType, _ContentKey) \
+    class _Name \
+        : public StateEvent<EventContent::SimpleContent<_ContentType>> \
+    { \
+        public: \
+            static constexpr const char* TypeId = _TypeId; \
+            explicit _Name(const QJsonObject& obj) \
+                : StateEvent(_EnumType, obj, #_ContentKey) \
+            { } \
+            template <typename T> \
+            explicit _Name(T&& value) \
+                : StateEvent(_EnumType, #_ContentKey, \
+                             std::forward<T>(value)) \
+            { } \
+            _ContentType _ContentKey() const { return content().value; } \
+    };
+
+    DECLARE_SIMPLE_STATE_EVENT(RoomNameEvent, "m.room.name",
+                               Event::Type::RoomName, QString, name)
+    DECLARE_SIMPLE_STATE_EVENT(RoomAliasesEvent, "m.room.aliases",
+                               Event::Type::RoomAliases, QStringList, aliases)
+    DECLARE_SIMPLE_STATE_EVENT(RoomCanonicalAliasEvent, "m.room.canonical_alias",
+                               Event::Type::RoomCanonicalAlias, QString, alias)
+    DECLARE_SIMPLE_STATE_EVENT(RoomTopicEvent, "m.room.topic",
+                               Event::Type::RoomTopic, QString, topic)
+    DECLARE_SIMPLE_STATE_EVENT(EncryptionEvent, "m.room.encryption",
+                               Event::Type::RoomEncryption, QString, algorithm)
+} // namespace QMatrixClient