[gtksourceview] Completion: rework move_page()

[Sébastien Wilmet <swilmet src gnome org>]

commit 744dce25bf82144bf53ab8fc37fa3f0e75030a24
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Tue Feb 26 23:21:06 2013 +0100

    Completion: rework move_page()
    
    The previous code was hard to understand, because it was generic. A less
    generic code is easier to understand, and it appears that it is shorter.

 gtksourceview/gtksourcecompletion.c |  353 +++++++++++++++-------------------
 1 files changed, 156 insertions(+), 197 deletions(-)
---
diff --git a/gtksourceview/gtksourcecompletion.c b/gtksourceview/gtksourcecompletion.c
index a90a84d..62b2fbf 100644
--- a/gtksourceview/gtksourcecompletion.c
+++ b/gtksourceview/gtksourcecompletion.c
@@ -587,194 +587,6 @@ update_selection_label (GtkSourceCompletion *completion)
 }
 
 static void
-visible_provider_changed (GtkSourceCompletion *completion)
-{
-       GtkTreeSelection *selection;
-       GtkTreeIter iter;
-
-       update_selection_label (completion);
-
-       selection = gtk_tree_view_get_selection (completion->priv->tree_view_proposals);
-
-       if (gtk_tree_selection_get_selected (selection, NULL, &iter))
-       {
-               scroll_to_iter (completion, &iter);
-       }
-       else
-       {
-               gtk_tree_view_scroll_to_point (completion->priv->tree_view_proposals, 0, 0);
-       }
-}
-
-typedef GList * (*ListSelector)(GList *);
-
-static gboolean
-select_provider (GtkSourceCompletion *completion,
-                 ListSelector         advance,
-                 ListSelector         cycle_first,
-                 ListSelector         cycle_last,
-                 guint                num_advance)
-{
-       GList *first;
-       GList *last;
-       GList *orig;
-       GList *current;
-       GtkSourceCompletionProvider *provider;
-       guint num;
-       guint pos;
-       GList *providers;
-       GtkSourceCompletionProvider *visible;
-       guint i;
-
-       visible = get_visible_provider (completion);
-
-       get_num_visible_providers (completion, &num, &pos);
-
-       if (num <= 1)
-       {
-               if (visible != NULL)
-               {
-                       gtk_source_completion_model_set_visible_providers (
-                                       completion->priv->model_proposals,
-                                       NULL);
-
-                       visible_provider_changed (completion);
-                       return TRUE;
-               }
-
-               return FALSE;
-       }
-
-       providers = gtk_source_completion_model_get_providers (completion->priv->model_proposals);
-
-       if (visible != NULL)
-       {
-               orig = g_list_find (providers, visible);
-       }
-       else
-       {
-               orig = NULL;
-       }
-
-       first = cycle_first ? cycle_first (providers) : NULL;
-       last = cycle_last ? cycle_last (providers) : NULL;
-
-       current = orig;
-
-       for (i = 0; i < num_advance; ++i)
-       {
-               do
-               {
-                       if (current == NULL)
-                       {
-                               current = first;
-                       }
-                       else if (current == last)
-                       {
-                               current = NULL;
-                       }
-                       else
-                       {
-                               current = advance (current);
-                       }
-
-                       if (current != NULL)
-                       {
-                               provider = GTK_SOURCE_COMPLETION_PROVIDER (current->data);
-
-                               if (gtk_source_completion_model_n_proposals 
(completion->priv->model_proposals,
-                                                                            provider) != 0)
-                               {
-                                       break;
-                               }
-                       }
-                       else if (!gtk_source_completion_model_is_empty (completion->priv->model_proposals, 
FALSE))
-                       {
-                               break;
-                       }
-               } while (orig != current);
-       }
-
-       if (orig == current)
-       {
-               g_list_free (providers);
-               return FALSE;
-       }
-
-       if (current != NULL)
-       {
-               GList *visible_providers = g_list_append (NULL, current->data);
-
-               gtk_source_completion_model_set_visible_providers (completion->priv->model_proposals,
-                                                                  visible_providers);
-               g_list_free (visible_providers);
-               visible_provider_changed (completion);
-       }
-       else
-       {
-               gtk_source_completion_model_set_visible_providers (completion->priv->model_proposals,
-                                                                  NULL);
-               visible_provider_changed (completion);
-       }
-
-       g_list_free (providers);
-       return TRUE;
-}
-
-static GList *
-wrap_g_list_next (GList *list)
-{
-       return g_list_next (list);
-}
-
-static GList *
-wrap_g_list_previous (GList *list)
-{
-       return g_list_previous (list);
-}
-
-static gboolean
-select_next_provider (GtkSourceCompletion *completion,
-                      guint                num)
-{
-       return select_provider (completion,
-                               wrap_g_list_next,
-                               g_list_first,
-                               g_list_last,
-                               num);
-}
-
-static gboolean
-select_previous_provider (GtkSourceCompletion *completion,
-                          guint                num)
-{
-       return select_provider (completion,
-                               wrap_g_list_previous,
-                               g_list_last,
-                               g_list_first,
-                               num);
-}
-
-static gboolean
-select_last_provider (GtkSourceCompletion *completion)
-{
-       return select_provider (completion, g_list_last, g_list_last, NULL, 1);
-}
-
-static GList *
-select_first_provider_wrap (GList *list)
-{
-       /* Basicly, this means selecting 'All', which is just selection NULL */
-       return NULL;
-}
-
-static gboolean
-select_first_provider (GtkSourceCompletion *completion)
-{
-       return select_provider (completion, select_first_provider_wrap, NULL, NULL, 1);
-}
-
-static void
 update_info_position (GtkSourceCompletion *completion)
 {
        GdkScreen *screen;
@@ -1007,26 +819,161 @@ check_first_selected (GtkSourceCompletion *completion)
        scroll_to_iter (completion, &iter);
 }
 
+static GList *
+get_last_provider (GtkSourceCompletion *completion)
+{
+       GList *providers = gtk_source_completion_model_get_providers (completion->priv->model_proposals);
+       GList *ret;
+
+       g_return_val_if_fail (providers != NULL, NULL);
+
+       if (providers->next == NULL)
+       {
+               ret = NULL;
+       }
+       else
+       {
+               ret = g_list_copy (g_list_last (providers));
+       }
+
+       g_list_free (providers);
+       return ret;
+}
+
+static GList *
+providers_cycle_forward (GList *all_providers,
+                        GList *position,
+                        gint   num)
+{
+       GList *l = position;
+       gint i;
+
+       if (all_providers == NULL || all_providers->next == NULL)
+       {
+               return NULL;
+       }
+
+       for (i = 0; i < num; i++)
+       {
+               l = l == NULL ? all_providers : l->next;
+       }
+
+       return l;
+}
+
+static GList *
+providers_cycle_backward (GList *all_providers,
+                         GList *position,
+                         gint   num)
+{
+       gint i;
+       GList *l = position;
+       GList *end = g_list_last (all_providers);
+
+       if (all_providers == NULL || all_providers->next == NULL)
+       {
+               return NULL;
+       }
+
+       for (i = 0; i < num; i++)
+       {
+               l = l == NULL ? end : l->prev;
+       }
+
+       return l;
+}
+
+static GList *
+get_next_provider (GtkSourceCompletion *completion,
+                  gint                 num)
+{
+       GList *providers;
+       GList *visible_providers;
+       GList *position;
+       GList *ret;
+
+       providers = gtk_source_completion_model_get_providers (completion->priv->model_proposals);
+       visible_providers = gtk_source_completion_model_get_visible_providers 
(completion->priv->model_proposals);
+
+       if (visible_providers == NULL)
+       {
+               position = NULL;
+       }
+       else
+       {
+               position = g_list_find (providers, visible_providers->data);
+       }
+
+       position = providers_cycle_forward (providers, position, num);
+
+       if (position == NULL)
+       {
+               ret = NULL;
+       }
+       else
+       {
+               ret = g_list_append (NULL, position->data);
+       }
+
+       g_list_free (providers);
+
+       return ret;
+}
+
+static GList *
+get_previous_provider (GtkSourceCompletion *completion,
+                      gint                 num)
+{
+       GList *providers;
+       GList *visible_providers;
+       GList *position;
+       GList *ret;
+
+       providers = gtk_source_completion_model_get_providers (completion->priv->model_proposals);
+       visible_providers = gtk_source_completion_model_get_visible_providers 
(completion->priv->model_proposals);
+
+       if (visible_providers == NULL)
+       {
+               position = NULL;
+       }
+       else
+       {
+               position = g_list_find (providers, visible_providers->data);
+       }
+
+       position = providers_cycle_backward (providers, position, num);
+
+       if (position == NULL)
+       {
+               ret = NULL;
+       }
+       else
+       {
+               ret = g_list_append (NULL, position->data);
+       }
+
+       g_list_free (providers);
+
+       return ret;
+}
+
 static void
 gtk_source_completion_move_page (GtkSourceCompletion *completion,
                                  GtkScrollStep        step,
                                  gint                 num)
 {
-       GtkTreeSelection *selection = gtk_tree_view_get_selection (completion->priv->tree_view_proposals);
-
-       /* Unselect all, so the first proposal is selected if needed, after the
-        * page move. */
-       gtk_tree_selection_unselect_all (selection);
+       GtkTreeSelection *selection;
+       GList *visible_providers = NULL;
 
        if (step == GTK_SCROLL_ENDS)
        {
                if (num > 0)
                {
-                       select_last_provider (completion);
+                       visible_providers = get_last_provider (completion);
                }
                else
                {
-                       select_first_provider (completion);
+                       visible_providers = NULL;
                }
        }
        else
@@ -1038,15 +985,27 @@ gtk_source_completion_move_page (GtkSourceCompletion *completion,
 
                if (num > 0)
                {
-                       select_next_provider (completion, num);
+                       visible_providers = get_next_provider (completion, num);
                }
                else
                {
-                       select_previous_provider (completion, -1 * num);
+                       visible_providers = get_previous_provider (completion, -1 * num);
                }
        }
 
+       gtk_source_completion_model_set_visible_providers (completion->priv->model_proposals,
+                                                          visible_providers);
+
+       update_selection_label (completion);
+
+       selection = gtk_tree_view_get_selection (completion->priv->tree_view_proposals);
+
+       /* Unselect all, so the first proposal is selected if needed. */
+       gtk_tree_selection_unselect_all (selection);
+
        check_first_selected (completion);
+
+       g_list_free (visible_providers);
 }
 
 static gboolean