[gtk+] cssnode: Loosen requirements for style caching

[Benjamin Otte <otte src gnome org>]

commit f1ca75d1812f95690f2bba7445ad6803b58d4780
Author: Benjamin Otte <otte redhat com>
Date:   Wed Aug 26 18:01:39 2015 +0200

    cssnode: Loosen requirements for style caching
    
    We can actually share :first-child/:last-child related things now,
    because we special case them. So the only positions we cannot cache are
    nth-child/nth-last-child.
    
    This should take care of a lot of Adwaita's styling.

 gtk/gtkcssnode.c |   45 +++++++++++++++++++++++++++++++++++++++------
 1 files changed, 39 insertions(+), 6 deletions(-)
---
diff --git a/gtk/gtkcssnode.c b/gtk/gtkcssnode.c
index 9d76f2a..3cc7e16 100644
--- a/gtk/gtkcssnode.c
+++ b/gtk/gtkcssnode.c
@@ -181,6 +181,10 @@ gtk_css_node_finalize (GObject *object)
   G_OBJECT_CLASS (gtk_css_node_parent_class)->finalize (object);
 }
 
+#define UNPACK_DECLARATION(packed) ((GtkCssNodeDeclaration *) (GPOINTER_TO_SIZE (packed) & ~0x3))
+#define UNPACK_FLAGS(packed) (GPOINTER_TO_SIZE (packed) & 0x3)
+#define PACK(decl, first_child, last_child) GSIZE_TO_POINTER (GPOINTER_TO_SIZE (decl) | ((first_child) ? 0x2 
: 0) | ((last_child) ? 0x1 : 0))
+
 static gboolean
 may_use_global_parent_cache (GtkCssNode *node)
 {
@@ -214,7 +218,10 @@ lookup_in_global_parent_cache (GtkCssNode                  *node,
   if (cache == NULL)
     return NULL;
 
-  style = g_hash_table_lookup (cache, decl);
+  style = g_hash_table_lookup (cache,
+                               PACK (decl,
+                                     gtk_css_node_get_previous_sibling (node) == NULL,
+                                     gtk_css_node_get_next_sibling (node) == NULL));
 
   return style;
 }
@@ -235,12 +242,36 @@ may_be_stored_in_parent_cache (GtkCssStyle *style)
   /* Again, the cache is shared between all children of the parent.
    * If the position is relevant, no child has the same style.
    */
-  if (change & GTK_CSS_CHANGE_POSITION)
+  if (change & (GTK_CSS_CHANGE_NTH_CHILD | GTK_CSS_CHANGE_NTH_LAST_CHILD))
     return FALSE;
 
   return TRUE;
 }
 
+static guint
+gtk_global_parent_cache_hash (gconstpointer item)
+{
+  return gtk_css_node_declaration_hash (UNPACK_DECLARATION (item)) << 2
+    || UNPACK_FLAGS (item);
+}
+
+static gboolean
+gtk_global_parent_cache_equal (gconstpointer item1,
+                               gconstpointer item2)
+{
+  if (UNPACK_FLAGS (item1) != UNPACK_FLAGS (item2))
+    return FALSE;
+
+  return gtk_css_node_declaration_equal (UNPACK_DECLARATION (item1),
+                                         UNPACK_DECLARATION (item2));
+}
+
+static void
+gtk_global_parent_cache_free (gpointer item)
+{
+  gtk_css_node_declaration_unref (UNPACK_DECLARATION (item));
+}
+
 static void
 store_in_global_parent_cache (GtkCssNode                  *node,
                               GtkCssStyle                 *parent,
@@ -261,15 +292,17 @@ store_in_global_parent_cache (GtkCssNode                  *node,
   cache = g_object_get_data (G_OBJECT (parent), "gtk-global-cache");
   if (cache == NULL)
     {
-      cache = g_hash_table_new_full (gtk_css_node_declaration_hash,
-                                     gtk_css_node_declaration_equal,
-                                     (GDestroyNotify) gtk_css_node_declaration_unref,
+      cache = g_hash_table_new_full (gtk_global_parent_cache_hash,
+                                     gtk_global_parent_cache_equal,
+                                     gtk_global_parent_cache_free,
                                      g_object_unref);
       g_object_set_data_full (G_OBJECT (parent), "gtk-global-cache", cache, (GDestroyNotify) 
g_hash_table_destroy);
     }
 
   g_hash_table_insert (cache,
-                       gtk_css_node_declaration_ref ((GtkCssNodeDeclaration *) decl),
+                       PACK (gtk_css_node_declaration_ref ((GtkCssNodeDeclaration *) decl),
+                             gtk_css_node_get_previous_sibling (node) == NULL,
+                             gtk_css_node_get_next_sibling (node) == NULL),
                        g_object_ref (style));
 }