Cleanup QDBusArgument marshalling for containers

There's no need to specialize the marshalling for QList, QHash and QMap
when we can simply have generic code here that works for all containers

Change-Id: I442ac6009953d2bd8e5a7012262cffeb8e912034
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/dbus/qdbusargument.cpp

@@ -908,9 +908,10 @@ void QDBusArgument::endArray()
 
     \snippet code/src_qdbus_qdbusargument.cpp 7
 
-    If the type you want to marshall is a QMap or QHash, you need not
+    You usually don't need to provide an \c{operator<<} or \c{operator>>}
-    declare an \c{operator<<} function for it, since Qt D-Bus provides
+    function for associative containers such as QHash or std::map,
-    generic templates to do the job of marshalling the data.
+    since Qt D-Bus provides generic templates to do the job of marshalling
+    the data.
 
     \sa endMap(), beginStructure(), beginArray(), beginMapEntry()
 */

src/dbus/qdbusargument.h

@@ -224,7 +224,8 @@ Q_DBUS_EXPORT const QDBusArgument &operator>>(const QDBusArgument &a, QLineF &li
 Q_DBUS_EXPORT QDBusArgument &operator<<(QDBusArgument &a, const QLineF &line);
 #endif
 
-template<template <typename> class Container, typename T>
+template<template <typename> class Container, typename T,
+         typename = typename Container<T>::iterator>
 inline QDBusArgument &operator<<(QDBusArgument &arg, const Container<T> &list)
 {
     int id = qMetaTypeId<T>();
@@ -237,7 +238,8 @@ inline QDBusArgument &operator<<(QDBusArgument &arg, const Container<T> &list)
     return arg;
 }
 
-template<template <typename> class Container, typename T>
+template<template <typename> class Container, typename T,
+         typename = typename Container<T>::iterator>
 inline const QDBusArgument &operator>>(const QDBusArgument &arg, Container<T> &list)
 {
     arg.beginArray();
@@ -252,35 +254,6 @@ inline const QDBusArgument &operator>>(const QDBusArgument &arg, Container<T> &l
     return arg;
 }
 
-// QList specializations
-template<typename T>
-inline QDBusArgument &operator<<(QDBusArgument &arg, const QList<T> &list)
-{
-    int id = qMetaTypeId<T>();
-    arg.beginArray(id);
-    typename QList<T>::ConstIterator it = list.constBegin();
-    typename QList<T>::ConstIterator end = list.constEnd();
-    for ( ; it != end; ++it)
-        arg << *it;
-    arg.endArray();
-    return arg;
-}
-
-template<typename T>
-inline const QDBusArgument &operator>>(const QDBusArgument &arg, QList<T> &list)
-{
-    arg.beginArray();
-    list.clear();
-    while (!arg.atEnd()) {
-        T item;
-        arg >> item;
-        list.push_back(item);
-    }
-    arg.endArray();
-
-    return arg;
-}
-
 inline QDBusArgument &operator<<(QDBusArgument &arg, const QVariantList &list)
 {
     int id = qMetaTypeId<QDBusVariant>();
@@ -293,15 +266,16 @@ inline QDBusArgument &operator<<(QDBusArgument &arg, const QVariantList &list)
     return arg;
 }
 
-// QMap specializations
+// Specializations for associative containers
-template<typename Key, typename T>
+template <template <typename, typename> class Container, typename Key, typename T,
-inline QDBusArgument &operator<<(QDBusArgument &arg, const QMap<Key, T> &map)
+         QtPrivate::IfAssociativeIteratorHasKeyAndValue<typename Container<Key, T>::iterator> = true>
+inline QDBusArgument &operator<<(QDBusArgument &arg, const Container<Key, T> &map)
 {
     int kid = qMetaTypeId<Key>();
     int vid = qMetaTypeId<T>();
     arg.beginMap(kid, vid);
-    typename QMap<Key, T>::ConstIterator it = map.constBegin();
+    auto it = map.begin();
-    typename QMap<Key, T>::ConstIterator end = map.constEnd();
+    auto end = map.end();
     for ( ; it != end; ++it) {
         arg.beginMapEntry();
         arg << it.key() << it.value();
@@ -311,8 +285,27 @@ inline QDBusArgument &operator<<(QDBusArgument &arg, const QMap<Key, T> &map)
     return arg;
 }
 
-template<typename Key, typename T>
+template <template <typename, typename> class Container, typename Key, typename T,
-inline const QDBusArgument &operator>>(const QDBusArgument &arg, QMap<Key, T> &map)
+         QtPrivate::IfAssociativeIteratorHasFirstAndSecond<typename Container<Key, T>::iterator> = true>
+inline QDBusArgument &operator<<(QDBusArgument &arg, const Container<Key, T> &map)
+{
+    int kid = qMetaTypeId<Key>();
+    int vid = qMetaTypeId<T>();
+    arg.beginMap(kid, vid);
+    auto it = map.begin();
+    auto end = map.end();
+    for ( ; it != end; ++it) {
+        arg.beginMapEntry();
+        arg << it->first << it->second;
+        arg.endMapEntry();
+    }
+    arg.endMap();
+    return arg;
+}
+
+template <template <typename, typename> class Container, typename Key, typename T,
+         typename = typename Container<Key, T>::iterator>
+inline const QDBusArgument &operator>>(const QDBusArgument &arg, Container<Key, T> &map)
 {
     arg.beginMap();
     map.clear();
@@ -321,7 +314,7 @@ inline const QDBusArgument &operator>>(const QDBusArgument &arg, QMap<Key, T> &m
         T value;
         arg.beginMapEntry();
         arg >> key >> value;
-        static_cast<QMultiMap<Key, T> &>(map).insert(key, value);
+        map.insert(key, value);
         arg.endMapEntry();
     }
     arg.endMap();
@@ -342,41 +335,6 @@ inline QDBusArgument &operator<<(QDBusArgument &arg, const QVariantMap &map)
     return arg;
 }
 
-// QHash specializations
-template<typename Key, typename T>
-inline QDBusArgument &operator<<(QDBusArgument &arg, const QHash<Key, T> &map)
-{
-    int kid = qMetaTypeId<Key>();
-    int vid = qMetaTypeId<T>();
-    arg.beginMap(kid, vid);
-    typename QHash<Key, T>::ConstIterator it = map.constBegin();
-    typename QHash<Key, T>::ConstIterator end = map.constEnd();
-    for ( ; it != end; ++it) {
-        arg.beginMapEntry();
-        arg << it.key() << it.value();
-        arg.endMapEntry();
-    }
-    arg.endMap();
-    return arg;
-}
-
-template<typename Key, typename T>
-inline const QDBusArgument &operator>>(const QDBusArgument &arg, QHash<Key, T> &map)
-{
-    arg.beginMap();
-    map.clear();
-    while (!arg.atEnd()) {
-        Key key;
-        T value;
-        arg.beginMapEntry();
-        arg >> key >> value;
-        static_cast<QMultiHash<Key, T> &>(map).insert(key, value);
-        arg.endMapEntry();
-    }
-    arg.endMap();
-    return arg;
-}
-
 inline QDBusArgument &operator<<(QDBusArgument &arg, const QVariantHash &map)
 {
     arg.beginMap(QMetaType::QString, qMetaTypeId<QDBusVariant>());