[gtk/stack-fixes] selection model: Add a method to query the selection

[Matthias Clasen <matthiasc src gnome org>]

commit 8ee9f817195906594809e4b8398991bffe0fa50f
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Feb 10 00:27:29 2019 -0500

    selection model: Add a method to query the selection
    
    The query_range method allows to iterate over ranges of
    uniform selection. The default implementation always returns
    single-element ranges, so is not any better than iterating
    the elements one-by-one, but more efficient implementations
    are possible.

 gtk/gtkselectionmodel.c | 36 ++++++++++++++++++++++++++++++++++++
 gtk/gtkselectionmodel.h |  7 +++++++
 2 files changed, 43 insertions(+)
---
diff --git a/gtk/gtkselectionmodel.c b/gtk/gtkselectionmodel.c
index d004e3886d..cd4bbef35d 100644
--- a/gtk/gtkselectionmodel.c
+++ b/gtk/gtkselectionmodel.c
@@ -120,6 +120,15 @@ gtk_selection_model_default_unselect_all (GtkSelectionModel *model)
   return gtk_selection_model_unselect_range (model, 0, g_list_model_get_n_items (G_LIST_MODEL (model)));;
 }
 
+static gboolean
+gtk_selection_model_default_query_range (GtkSelectionModel *model,
+                                         guint             *position,
+                                         guint             *n_items)
+{
+  *n_items = 1;
+  return gtk_selection_model_is_selected (model, *position);  
+}
+
 static void
 gtk_selection_model_default_init (GtkSelectionModelInterface *iface)
 {
@@ -130,6 +139,7 @@ gtk_selection_model_default_init (GtkSelectionModelInterface *iface)
   iface->unselect_range = gtk_selection_model_default_unselect_range; 
   iface->select_all = gtk_selection_model_default_select_all; 
   iface->unselect_all = gtk_selection_model_default_unselect_all; 
+  iface->query_range = gtk_selection_model_default_query_range;
 
   /**
    * GtkSelectionModel::selection-changed
@@ -284,6 +294,32 @@ gtk_selection_model_get_model (GtkSelectionModel *model)
   return child;
 }
 
+/**
+ * gtk_selection_model_query_range:
+ * @model: a #GtkSelectionModel
+ * @position: (inout): specifies the position on input, and the first element of the range on output
+ * @n_items: (out): returns the size of the range
+ *
+ * This function allows to query the selection status of multiple elements at once.
+ * It is passed a position and returns a range of elements of uniform selection status.
+ * The returned range is guaranteed to include the passed-in position.
+ * The selection status is returned from this function.
+ *
+ * Returns: %TRUE if the elements in the returned range are selected, %FALSE otherwise
+ */
+gboolean
+gtk_selection_model_query_range (GtkSelectionModel *model,
+                                 guint             *position,
+                                 guint             *n_items)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), FALSE);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->query_range (model, position, n_items);
+}
+
 void
 gtk_selection_model_selection_changed (GtkSelectionModel *model,
                                        guint              position,
diff --git a/gtk/gtkselectionmodel.h b/gtk/gtkselectionmodel.h
index c3add80f0a..cd0175e398 100644
--- a/gtk/gtkselectionmodel.h
+++ b/gtk/gtkselectionmodel.h
@@ -79,6 +79,9 @@ struct _GtkSelectionModelInterface
                                                                  guint                   n_items);
   gboolean              (* select_all)                          (GtkSelectionModel      *model);
   gboolean              (* unselect_all)                        (GtkSelectionModel      *model);
+  gboolean              (* query_range)                         (GtkSelectionModel      *model,
+                                                                 guint                  *position,
+                                                                 guint                  *n_items);
 };
 
 GDK_AVAILABLE_IN_ALL
@@ -108,6 +111,10 @@ gboolean                gtk_selection_model_unselect_all        (GtkSelectionMod
 
 GDK_AVAILABLE_IN_ALL
 GListModel *            gtk_selection_model_get_model           (GtkSelectionModel      *model);
+GDK_AVAILABLE_IN_ALL
+gboolean                gtk_selection_model_query_range         (GtkSelectionModel      *model,
+                                                                 guint                  *position,
+                                                                 guint                  *n_items);
 
 /* for implementations only */
 GDK_AVAILABLE_IN_ALL