[gtk+/wip/cssnode3: 42/46] cssnode: Refactor node tree modification code

[Benjamin Otte <otte src gnome org>]

commit 022a60946065934ca0d3cbc9d2f8a6e575870dff
Author: Benjamin Otte <otte redhat com>
Date:   Mon Feb 9 22:03:13 2015 +0100

    cssnode: Refactor node tree modification code
    
    This allows adding more API for it.
    
    It also includes code that tracks modifications and invalidates siblings
    and their positions whenever nodes get added or removed.

 gtk/gtkcssnode.c        |  142 +++++++++++++++++++++++++++++++---------------
 gtk/gtkcssnodeprivate.h |    2 +-
 2 files changed, 97 insertions(+), 47 deletions(-)
---
diff --git a/gtk/gtkcssnode.c b/gtk/gtkcssnode.c
index 8a9027c..83ba092 100644
--- a/gtk/gtkcssnode.c
+++ b/gtk/gtkcssnode.c
@@ -206,73 +206,118 @@ gtk_css_node_parent_will_be_set (GtkCssNode *node)
     GTK_CSS_NODE_GET_CLASS (node)->dequeue_validate (node);
 }
 
-void
-gtk_css_node_set_parent (GtkCssNode *node,
-                         GtkCssNode *parent)
+static void
+gtk_css_node_unlink_from_siblings (GtkCssNode *node)
 {
-  if (node->parent == parent)
+  if (GTK_IS_CSS_TRANSIENT_NODE (node))
     return;
 
-  /* Take a reference here so the whole function has a reference */
-  g_object_ref (node);
+  if (node->previous_sibling)
+    node->previous_sibling->next_sibling = node->next_sibling;
+  else
+    node->parent->first_child = node->next_sibling;
 
-  if (node->parent != NULL)
+  if (node->next_sibling)
+    node->next_sibling->previous_sibling = node->previous_sibling;
+  else
+    node->parent->last_child = node->previous_sibling;
+
+  node->previous_sibling = NULL;
+  node->next_sibling = NULL;
+}
+
+static void
+gtk_css_node_link_to_siblings (GtkCssNode *node,
+                               GtkCssNode *new_previous)
+{
+  if (GTK_IS_CSS_TRANSIENT_NODE (node))
+    return;
+
+  if (new_previous)
     {
-      if (!GTK_IS_CSS_TRANSIENT_NODE (node))
-        {
-          if (node->previous_sibling)
-            node->previous_sibling->next_sibling = node->next_sibling;
-          else
-            node->parent->first_child = node->next_sibling;
+      node->previous_sibling = new_previous;
+      node->next_sibling = new_previous->next_sibling;
+      new_previous->next_sibling = node;
+    }
+  else
+    {
+      node->next_sibling = node->parent->first_child;
+      node->parent->first_child = node;
+    }
+
+  if (node->next_sibling)
+    node->next_sibling->previous_sibling = node;
+  else
+    node->parent->last_child = node;
+}
 
-          if (node->next_sibling)
-            node->next_sibling->previous_sibling = node->previous_sibling;
-          else
-            node->parent->last_child = node->previous_sibling;
+static void
+gtk_css_node_set_children_changed (GtkCssNode *node)
+{
+  if (node->children_changed)
+    return;
 
-          node->parent->n_children--;
-        }
+  node->children_changed = TRUE;
+  gtk_css_node_set_invalid (node, TRUE);
+}
 
-      node->parent = NULL;
-      node->next_sibling = NULL;
-      node->previous_sibling = NULL;
+static void
+gtk_css_node_reposition (GtkCssNode *node,
+                         GtkCssNode *parent,
+                         GtkCssNode *previous)
+{
+  g_assert (! (parent == NULL && previous != NULL));
 
-      g_object_unref (node);
+  /* Take a reference here so the whole function has a reference */
+  g_object_ref (node);
 
-      if (parent == NULL)
-        gtk_css_node_parent_was_unset (node);
-    }
+  if (node->parent != NULL)
+    gtk_css_node_unlink_from_siblings (node);
 
-  if (parent)
+  if (node->parent != parent)
     {
       if (node->parent == NULL)
-        gtk_css_node_parent_will_be_set (node);
+        {
+          gtk_css_node_parent_will_be_set (node);
+        }
+      else
+        {
+          g_object_unref (node);
+          gtk_css_node_set_children_changed (node->parent);
+        }
 
       node->parent = parent;
 
-      if (!GTK_IS_CSS_TRANSIENT_NODE (node))
+      if (parent)
         {
-          parent->n_children++;
+          gtk_css_node_set_children_changed (parent);
+          g_object_ref (node);
 
-          if (parent->last_child)
-            {
-              parent->last_child->next_sibling = node;
-              node->previous_sibling = parent->last_child;
-            }
-          parent->last_child = node;
-
-          if (parent->first_child == NULL)
-            parent->first_child = node;
+          if (node->invalid)
+            gtk_css_node_set_invalid (parent, TRUE);
+        }
+      else
+        {
+          gtk_css_node_parent_was_unset (node);
         }
-
-      if (node->invalid)
-        gtk_css_node_set_invalid (parent, TRUE);
     }
 
+  if (parent)
+    gtk_css_node_link_to_siblings (node, previous);
+
   gtk_css_node_invalidate (node, GTK_CSS_CHANGE_ANY_PARENT | GTK_CSS_CHANGE_ANY_SIBLING);
 
-  if (node->parent == NULL)
-    g_object_unref (node);
+  g_object_unref (node);
+}
+
+void
+gtk_css_node_set_parent (GtkCssNode *node,
+                         GtkCssNode *parent)
+{
+  if (node->parent == parent)
+    return;
+
+  gtk_css_node_reposition (node, parent, parent ? parent->last_child : NULL);
 }
 
 GtkCssNode *
@@ -637,6 +682,11 @@ gtk_css_node_propagate_pending_changes (GtkCssNode *cssnode)
     return;
 
   change = _gtk_css_change_for_child (cssnode->pending_changes);
+  if (cssnode->children_changed)
+    {
+      change |= GTK_CSS_CHANGE_POSITION | GTK_CSS_CHANGE_ANY_SIBLING;
+      cssnode->children_changed = FALSE;
+    }
 
   for (child = gtk_css_node_get_first_child (cssnode);
        child;
@@ -670,11 +720,11 @@ gtk_css_node_validate (GtkCssNode            *cssnode,
   if (G_UNLIKELY (gtk_get_debug_flags () & GTK_DEBUG_NO_CSS_CACHE))
     change = GTK_CSS_CHANGE_ANY;
 
+  gtk_css_node_propagate_pending_changes (cssnode);
+
   if (!cssnode->invalid && change == 0 && _gtk_bitmask_is_empty (parent_changes))
     return;
 
-  gtk_css_node_propagate_pending_changes (cssnode);
-
   gtk_css_node_set_invalid (cssnode, FALSE);
 
   change = cssnode->pending_changes;
diff --git a/gtk/gtkcssnodeprivate.h b/gtk/gtkcssnodeprivate.h
index 4207d2f..b1339b0 100644
--- a/gtk/gtkcssnodeprivate.h
+++ b/gtk/gtkcssnodeprivate.h
@@ -43,7 +43,6 @@ struct _GtkCssNode
   GtkCssNode *next_sibling;
   GtkCssNode *first_child;
   GtkCssNode *last_child;
-  guint n_children;
 
   GtkCssNodeDeclaration *decl;
   GtkCssStyle           *style;
@@ -51,6 +50,7 @@ struct _GtkCssNode
   GtkCssChange           pending_changes;       /* changes that accumulated since the style was last 
computed */
 
   guint                  invalid :1;            /* node or a child needs to be validated (even if just for 
animation) */
+  guint                  children_changed :1;   /* the children changed since last validation */
 };
 
 struct _GtkCssNodeClass