Enable natural sort in the nations view

Closes #2050.

client/CMakeLists.txt

@@ -119,6 +119,7 @@ target_sources(
   tileset/layer.cpp
   tileset/sprite.cpp
   tileset/tilespec.cpp
+  utils/collated_sort_proxy.cpp
   utils/colorizer.cpp
   utils/improvement_seller.cpp
   utils/unit_quick_menu.cpp

client/utils/collated_sort_proxy.cpp

@@ -0,0 +1,60 @@
+/*
+ * SPDX-License-Identifier: GPLv3-or-later
+ * SPDX-FileCopyrightText: Louis Moureaux <[email protected]>
+ */
+
+#include "collated_sort_proxy.h"
+
+namespace freeciv {
+
+/**
+ * \class collated_sort_filter_proxy_model
+ * \brief A sort and filter proxy model supporting string collation.
+ *
+ * This model can be used when strings in a model should use a "natural" sort
+ * order.
+ */
+
+/**
+ * \brief Constructor.
+ */
+collated_sort_filter_proxy_model::collated_sort_filter_proxy_model(
+    QObject *parent)
+    : QSortFilterProxyModel(parent)
+{
+}
+
+/**
+ * \brief Changes the collator currently in use.
+ */
+void collated_sort_filter_proxy_model::set_collator(const QCollator &coll)
+{
+  m_collator = coll;
+  invalidate();
+}
+
+/**
+ * \brief Reimplemented protected function.
+ *
+ * This overrides @c QSortFilterProxyModel::lessThan to use the collator when
+ * comparing strings.
+ */
+bool collated_sort_filter_proxy_model::lessThan(
+    const QModelIndex &source_left, const QModelIndex &source_right) const
+{
+  // Copied from QSortFilterProxyModel
+  QVariant l = (source_left.model()
+                    ? source_left.model()->data(source_left, sortRole())
+                    : QVariant());
+  QVariant r = (source_right.model()
+                    ? source_right.model()->data(source_right, sortRole())
+                    : QVariant());
+
+  if (l.type() == QVariant::String && r.type() == QVariant::String) {
+    return m_collator(l.toString(), r.toString());
+  }
+
+  return QSortFilterProxyModel::lessThan(source_left, source_right);
+}
+
+} // namespace freeciv

client/utils/collated_sort_proxy.h

@@ -0,0 +1,28 @@
+/*
+ * SPDX-License-Identifier: GPLv3-or-later
+ * SPDX-FileCopyrightText: Louis Moureaux <[email protected]>
+ */
+
+#pragma once
+
+#include <QCollator>
+#include <QSortFilterProxyModel>
+
+namespace freeciv {
+
+class collated_sort_filter_proxy_model : public QSortFilterProxyModel {
+  QCollator m_collator;
+
+public:
+  collated_sort_filter_proxy_model(QObject *parent = nullptr);
+
+  /// Retrieves the string collator currently in use.
+  QCollator collator() const { return m_collator; }
+  void set_collator(const QCollator &coll);
+
+protected:
+  bool lessThan(const QModelIndex &source_left,
+                const QModelIndex &source_right) const override;
+};
+
+} // namespace freeciv

client/views/view_nations.cpp

@@ -18,6 +18,7 @@
 #include <QMouseEvent>
 #include <QPainter>
 #include <QSortFilterProxyModel>
+#include <qnamespace.h>
 // utility
 #include "astring.h"
 #include "fcintl.h"
@@ -30,6 +31,7 @@
 #include "improvement.h"
 #include "nation.h"
 #include "research.h"
+#include "utils/collated_sort_proxy.h"
 #include "views/view_nations_data.h"
 // client
 #include "chatline_common.h"
@@ -315,11 +317,18 @@ plr_widget::plr_widget(QWidget *widget) : QTableView(widget)
   pid = new plr_item_delegate(this);
   setItemDelegate(pid);
   list_model = new plr_model(this);
-  filter_model = new QSortFilterProxyModel();
+
+  filter_model = new freeciv::collated_sort_filter_proxy_model;
   filter_model->setDynamicSortFilter(true);
   filter_model->setSourceModel(list_model);
   filter_model->setFilterRole(Qt::DisplayRole);
+  QCollator coll;
+  coll.setCaseSensitivity(Qt::CaseInsensitive);
+  coll.setLocale(locale());
+  coll.setNumericMode(true);
+  filter_model->set_collator(coll);
   setModel(filter_model);
+
   setSortingEnabled(true);
   setSelectionMode(QAbstractItemView::SingleSelection);
   setAutoScroll(true);

client/views/view_nations.h

@@ -9,13 +9,15 @@
 **************************************************************************/
 #pragma once
 
+// client
+#include "utils/collated_sort_proxy.h"
+#include "views/view_nations_data.h"
+
 // Qt
 #include <QAbstractListModel>
 #include <QItemDelegate>
 #include <QTableView>
 #include <QWidget>
-// client
-#include "views/view_nations_data.h"
 
 class QHBoxLayout;
 class QItemSelection;
@@ -102,7 +104,7 @@ private slots:
 class plr_widget : public QTableView {
   Q_OBJECT
   plr_model *list_model;
-  QSortFilterProxyModel *filter_model;
+  freeciv::collated_sort_filter_proxy_model *filter_model;
   plr_item_delegate *pid;
   plr_report *plr;
   QString techs_known;