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sortlistmodel: add a fast path for get_section()

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This commit is contained in:
Benjamin Otte
2022-02-19 03:39:13 +01:00
parent 2259109e32
commit 778321cb7a
1 changed files with 99 additions and 19 deletions
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118
gtk/gtksortlistmodel.c
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@@ -204,28 +204,13 @@ gtk_sort_list_model_ensure_key (GtkSortListModel *self,
}
static void
gtk_sort_list_model_get_section (GtkSectionModel *model,
guint position,
guint *out_start,
guint *out_end)
gtk_sort_list_model_get_section_unsorted (GtkSortListModel *self,
guint position,
guint *out_start,
guint *out_end)
{
GtkSortListModel *self = GTK_SORT_LIST_MODEL (model);
gpointer *pos, *start, *end;
if (position >= self->n_items)
{
*out_start = self->n_items;
*out_end = G_MAXUINT;
return;
}
if (self->section_sort_keys == NULL)
{
*out_start = 0;
*out_end = self->n_items;
return;
}
pos = &self->positions[position];
gtk_sort_list_model_ensure_key (self, pos_from_key (self, *pos));
@@ -251,6 +236,101 @@ gtk_sort_list_model_get_section (GtkSectionModel *model,
*out_end = end - self->positions;
}
static void
gtk_sort_list_model_get_section_sorted (GtkSortListModel *self,
guint position,
guint *out_start,
guint *out_end)
{
gpointer *pos;
guint step, min, max, mid;
pos = &self->positions[position];
max = position;
step = 1;
while (max > 0)
{
min = max - MIN (max, step);
step *= 2;
if (gtk_sort_keys_compare (self->section_sort_keys, self->positions[min], *pos) == GTK_ORDERING_EQUAL)
{
max = min;
continue;
}
/* now min is different, max is equal, bsearch where that changes */
while (max - min > 1)
{
mid = (max + min) / 2;
if (gtk_sort_keys_compare (self->section_sort_keys, self->positions[mid], *pos) == GTK_ORDERING_EQUAL)
max = mid;
else
min = mid;
}
break;
}
*out_start = max;
min = position;
step = 1;
while (min < self->n_items - 1)
{
max = min + MIN (self->n_items - 1 - min, step);
step *= 2;
if (gtk_sort_keys_compare (self->section_sort_keys, self->positions[max], *pos) == GTK_ORDERING_EQUAL)
{
min = max;
continue;
}
/* now min is equal, max is different, bsearch where that changes */
while (max - min > 1)
{
mid = (max + min) / 2;
if (gtk_sort_keys_compare (self->section_sort_keys, self->positions[mid], *pos) == GTK_ORDERING_EQUAL)
min = mid;
else
max = mid;
}
break;
}
*out_end = min + 1;
}
static void
gtk_sort_list_model_get_section (GtkSectionModel *model,
guint position,
guint *out_start,
guint *out_end)
{
GtkSortListModel *self = GTK_SORT_LIST_MODEL (model);
if (position >= self->n_items)
{
*out_start = self->n_items;
*out_end = G_MAXUINT;
return;
}
if (self->section_sort_keys == NULL)
{
*out_start = 0;
*out_end = self->n_items;
return;
}
/* When the list is not sorted:
* - keys may not exist yet
* - equal items may not be adjacent
* So add a slow path that can deal with that, but is O(N).
* The fast path is O(log N) and will be used for I guess
* 99% of cases.
*/
if (self->sort_cb)
gtk_sort_list_model_get_section_unsorted (self, position, out_start, out_end);
else
gtk_sort_list_model_get_section_sorted (self, position, out_start, out_end);
}
static void
gtk_sort_list_model_section_model_init (GtkSectionModelInterface *iface)
{