ItemModel: Extract Method isVariantLessThan()

As noted in comments, QSortFilterProxyModel and QStandardItemModel
duplicate code to compare QVariant; extract this into a separate method
they can share.

Since there is only one common suitable header for both files,
the method was placed in qabstractitemmodel.cpp

Change-Id: I82bb4a2d6084059b8a70a8d556c16f1a29f4f686
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -47,6 +47,7 @@
 #include <qvector.h>
 #include <qstack.h>
 #include <qbitarray.h>
+#include <qdatetime.h>
 
 #include <limits.h>
 
@@ -547,6 +548,43 @@ const QHash<int,QByteArray> &QAbstractItemModelPrivate::defaultRoleNames()
     return *qDefaultRoleNames();
 }
 
+bool QAbstractItemModelPrivate::isVariantLessThan(const QVariant &left, const QVariant &right,
+                                                  Qt::CaseSensitivity cs, bool isLocaleAware)
+{
+    if (left.userType() == QVariant::Invalid)
+        return false;
+    if (right.userType() == QVariant::Invalid)
+        return true;
+    switch (left.userType()) {
+    case QVariant::Int:
+        return left.toInt() < right.toInt();
+    case QVariant::UInt:
+        return left.toUInt() < right.toUInt();
+    case QVariant::LongLong:
+        return left.toLongLong() < right.toLongLong();
+    case QVariant::ULongLong:
+        return left.toULongLong() < right.toULongLong();
+    case QMetaType::Float:
+        return left.toFloat() < right.toFloat();
+    case QVariant::Double:
+        return left.toDouble() < right.toDouble();
+    case QVariant::Char:
+        return left.toChar() < right.toChar();
+    case QVariant::Date:
+        return left.toDate() < right.toDate();
+    case QVariant::Time:
+        return left.toTime() < right.toTime();
+    case QVariant::DateTime:
+        return left.toDateTime() < right.toDateTime();
+    case QVariant::String:
+    default:
+        if (isLocaleAware)
+            return left.toString().localeAwareCompare(right.toString()) < 0;
+        else
+            return left.toString().compare(right.toString(), cs) < 0;
+    }
+}
+
 
 static uint typeOfVariant(const QVariant &value)
 {

src/corelib/itemmodels/qabstractitemmodel_p.h

@@ -150,6 +150,8 @@ public:
 
     QHash<int,QByteArray> roleNames;
     static const QHash<int,QByteArray> &defaultRoleNames();
+    static bool isVariantLessThan(const QVariant &left, const QVariant &right,
+                                  Qt::CaseSensitivity cs = Qt::CaseSensitive, bool isLocaleAware = false);
 };
 Q_DECLARE_TYPEINFO(QAbstractItemModelPrivate::Change, Q_MOVABLE_TYPE);
 

src/corelib/itemmodels/qsortfilterproxymodel.cpp

@@ -2652,40 +2652,7 @@ bool QSortFilterProxyModel::lessThan(const QModelIndex &source_left, const QMode
     Q_D(const QSortFilterProxyModel);
     QVariant l = (source_left.model() ? source_left.model()->data(source_left, d->sort_role) : QVariant());
     QVariant r = (source_right.model() ? source_right.model()->data(source_right, d->sort_role) : QVariant());
-    // Duplicated in QStandardItem::operator<()
+    return QAbstractItemModelPrivate::isVariantLessThan(l, r, d->sort_casesensitivity, d->sort_localeaware);
-    if (l.userType() == QVariant::Invalid)
-        return false;
-    if (r.userType() == QVariant::Invalid)
-        return true;
-    switch (l.userType()) {
-    case QVariant::Int:
-        return l.toInt() < r.toInt();
-    case QVariant::UInt:
-        return l.toUInt() < r.toUInt();
-    case QVariant::LongLong:
-        return l.toLongLong() < r.toLongLong();
-    case QVariant::ULongLong:
-        return l.toULongLong() < r.toULongLong();
-    case QMetaType::Float:
-        return l.toFloat() < r.toFloat();
-    case QVariant::Double:
-        return l.toDouble() < r.toDouble();
-    case QVariant::Char:
-        return l.toChar() < r.toChar();
-    case QVariant::Date:
-        return l.toDate() < r.toDate();
-    case QVariant::Time:
-        return l.toTime() < r.toTime();
-    case QVariant::DateTime:
-        return l.toDateTime() < r.toDateTime();
-    case QVariant::String:
-    default:
-        if (d->sort_localeaware)
-            return l.toString().localeAwareCompare(r.toString()) < 0;
-        else
-            return l.toString().compare(r.toString(), d->sort_casesensitivity) < 0;
-    }
-    return false;
 }
 
 /*!

src/gui/itemmodels/qstandarditemmodel.cpp

@@ -1865,36 +1865,7 @@ bool QStandardItem::operator<(const QStandardItem &other) const
 {
     const int role = model() ? model()->sortRole() : Qt::DisplayRole;
     const QVariant l = data(role), r = other.data(role);
-    // this code is copied from QSortFilterProxyModel::lessThan()
+    return QAbstractItemModelPrivate::isVariantLessThan(l, r);
-    if (l.userType() == QVariant::Invalid)
-        return false;
-    if (r.userType() == QVariant::Invalid)
-        return true;
-    switch (l.userType()) {
-    case QVariant::Int:
-        return l.toInt() < r.toInt();
-    case QVariant::UInt:
-        return l.toUInt() < r.toUInt();
-    case QVariant::LongLong:
-        return l.toLongLong() < r.toLongLong();
-    case QVariant::ULongLong:
-        return l.toULongLong() < r.toULongLong();
-    case QMetaType::Float:
-        return l.toFloat() < r.toFloat();
-    case QVariant::Double:
-        return l.toDouble() < r.toDouble();
-    case QVariant::Char:
-        return l.toChar() < r.toChar();
-    case QVariant::Date:
-        return l.toDate() < r.toDate();
-    case QVariant::Time:
-        return l.toTime() < r.toTime();
-    case QVariant::DateTime:
-        return l.toDateTime() < r.toDateTime();
-    case QVariant::String:
-    default:
-        return l.toString().compare(r.toString()) < 0;
-    }
 }
 
 /*!