[glom/gtkmm4v4: 30/37] gtkmm4: TreeModel_DB: Use const_iterator.

[Murray Cumming <murrayc src gnome org>]

commit 06522e46e8cad8582b9b41b83293d26eea711ab9
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Mar 15 11:25:07 2017 +0100

    gtkmm4: TreeModel_DB: Use const_iterator.

 glom/mode_data/datawidget/combo.cc        |    3 ++-
 glom/mode_data/datawidget/treemodel_db.cc |   20 ++++++++++++++++----
 glom/mode_data/datawidget/treemodel_db.h  |   17 +++++++++++++----
 3 files changed, 31 insertions(+), 9 deletions(-)
---
diff --git a/glom/mode_data/datawidget/combo.cc b/glom/mode_data/datawidget/combo.cc
index b5d065e..6d8c705 100644
--- a/glom/mode_data/datawidget/combo.cc
+++ b/glom/mode_data/datawidget/combo.cc
@@ -246,7 +246,8 @@ void ComboGlom::set_value(const Gnome::Gda::Value& value)
     if(this_value == value)
     {
       found = true;
-      set_active(row);
+      const auto iter = row.get_iter();
+      set_active(iter);
       break;
     }
   }
diff --git a/glom/mode_data/datawidget/treemodel_db.cc b/glom/mode_data/datawidget/treemodel_db.cc
index bc22748..a81729a 100644
--- a/glom/mode_data/datawidget/treemodel_db.cc
+++ b/glom/mode_data/datawidget/treemodel_db.cc
@@ -704,13 +704,13 @@ bool DbTreeModel::get_iter_vfunc(const Path& path, iterator& iter) const
    return iter_nth_root_child_vfunc(path[0], iter);
 }
 
-DbTreeModel::type_datamodel_row_index DbTreeModel::get_datamodel_row_index_from_tree_row_iter(const 
iterator& iter) const
+DbTreeModel::type_datamodel_row_index DbTreeModel::get_datamodel_row_index_from_tree_row_iter(const 
const_iterator& iter) const
 {
   return GPOINTER_TO_INT(iter.gobj()->user_data);
 }
 
 
-bool DbTreeModel::check_treeiter_validity(const iterator& iter) const
+bool DbTreeModel::check_treeiter_validity(const const_iterator& iter) const
 {
   if(!(iter->get_model_gobject()))
     return false;
@@ -848,7 +848,7 @@ void DbTreeModel::set_key_value(const TreeModel::iterator& iter, const DbValue&
   }
 }
 
-DbTreeModel::DbValue DbTreeModel::get_key_value(const TreeModel::iterator& iter) const
+DbTreeModel::DbValue DbTreeModel::get_key_value(const TreeModel::const_iterator& iter) const
 {
   if(check_treeiter_validity(iter))
   {
@@ -867,7 +867,7 @@ DbTreeModel::DbValue DbTreeModel::get_key_value(const TreeModel::iterator& iter)
   return DbValue();
 }
 
-bool DbTreeModel::get_is_placeholder(const TreeModel::iterator& iter) const
+bool DbTreeModel::get_is_placeholder(const TreeModel::const_iterator& iter) const
 {
   //g_warning("DbTreeModel::g et_is_placeholder()");
   if(check_treeiter_validity(iter))
@@ -904,6 +904,12 @@ bool DbTreeModel::row_was_removed(const type_datamodel_row_index& datamodel_row)
     return false; //If it was never accessed before then it has never been removed.
 }
 
+Gtk::TreeModel::const_iterator DbTreeModel::get_last_row() const
+{
+  auto non_const = const_cast<DbTreeModel*>(this);
+  return non_const->get_last_row();
+}
+
 Gtk::TreeModel::iterator DbTreeModel::get_last_row()
 {
   iterator result;
@@ -933,6 +939,12 @@ Gtk::TreeModel::iterator DbTreeModel::get_last_row()
   return result;
 }
 
+Gtk::TreeModel::const_iterator DbTreeModel::get_placeholder_row() const
+{
+  auto non_const = const_cast<DbTreeModel*>(this);
+  return non_const->get_placeholder_row();
+}
+
 Gtk::TreeModel::iterator DbTreeModel::get_placeholder_row()
 {
   iterator result;
diff --git a/glom/mode_data/datawidget/treemodel_db.h b/glom/mode_data/datawidget/treemodel_db.h
index 26537e9..09a1f9e 100644
--- a/glom/mode_data/datawidget/treemodel_db.h
+++ b/glom/mode_data/datawidget/treemodel_db.h
@@ -110,7 +110,7 @@ public:
   typedef DbTreeModelRow::DbValue DbValue;
 
   void set_is_not_placeholder(const TreeModel::iterator& iter);
-  bool get_is_placeholder(const TreeModel::iterator& iter) const;
+  bool get_is_placeholder(const TreeModel::const_iterator& iter) const;
 
   /** Set the value of the primary key for the specified row.
    */
@@ -118,17 +118,26 @@ public:
 
   /** Get the value of the primary key for the specified row.
    */
-  DbValue get_key_value(const TreeModel::iterator& iter) const;
+  DbValue get_key_value(const TreeModel::const_iterator& iter) const;
 
   /** Get the last row.
    * This will never return the placeholder row.
    */
   TreeModel::iterator get_last_row();
 
+  /** Get the last row.
+   * This will never return the placeholder row.
+   */
+  TreeModel::const_iterator get_last_row() const;
+
   /** Get the placeholder row.
    */
   TreeModel::iterator get_placeholder_row();
 
+  /** Get the placeholder row.
+   */
+  TreeModel::const_iterator get_placeholder_row() const;
+
   /** Removes the given row from the list store.
    * @param iter The iterator to the row to be removed.
    * @result An iterator to the next row, or end() if there is none.
@@ -187,9 +196,9 @@ private:
    void invalidate_iter(iterator& iter) const;
    bool row_was_removed(const type_datamodel_row_index& row_iter) const;
 
-   type_datamodel_row_index get_datamodel_row_index_from_tree_row_iter(const iterator& iter) const;
+   type_datamodel_row_index get_datamodel_row_index_from_tree_row_iter(const const_iterator& iter) const;
 
-   bool check_treeiter_validity(const iterator& iter) const;
+   bool check_treeiter_validity(const const_iterator& iter) const;
 
    //Structure:
    unsigned int m_columns_count;