[gtk/wip/otte/css: 5/5] cssselector: Only compute change once

[Benjamin Otte <otte src gnome org>]

commit 940754bc98ba0dca3c145eb86b48c50a3a31f562
Author: Benjamin Otte <otte redhat com>
Date:   Wed Jan 29 02:38:18 2020 +0100

    cssselector: Only compute change once
    
    When iterating over nodes, only the first node needs to collect change.
    We can omit it for all other nodes, because the collected change won't
    change.

 gtk/gtkcssselector.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)
---
diff --git a/gtk/gtkcssselector.c b/gtk/gtkcssselector.c
index 129c37b9c3..d78452e991 100644
--- a/gtk/gtkcssselector.c
+++ b/gtk/gtkcssselector.c
@@ -1934,16 +1934,19 @@ gtk_css_selector_tree_match (const GtkCssSelectorTree      *tree,
        prev != NULL;
        prev = gtk_css_selector_tree_get_sibling (prev))
     {
+      GtkCssChange child_change = 0;
+      GtkCssChange *child_change_ptr = change ? &child_change : NULL;
+
       for (child = gtk_css_selector_iterator (&tree->selector, node, NULL);
            child;
            child = gtk_css_selector_iterator (&tree->selector, node, child))
         {
-          GtkCssChange child_change = 0;
-          if (!gtk_css_selector_tree_match (prev, filter, match_filter, child, results, change ? 
&child_change : NULL))
+          if (!gtk_css_selector_tree_match (prev, filter, match_filter, child, results, child_change_ptr))
             break;
-          if (change)
-            *change |= child_change;
+          child_change_ptr = NULL;
         }
+      if (change)
+        *change |= child_change;
     }
 
   if (change && *change)
@@ -1959,15 +1962,17 @@ gtk_css_selector_tree_match_all (const GtkCssSelectorTree     *tree,
                                  GtkCssChange                 *change)
 {
   GPtrArray *results = NULL;
+  const GtkCssSelectorTree *iter;
 
   if (change)
     *change = 0;
 
-  for (; tree != NULL;
-       tree = gtk_css_selector_tree_get_sibling (tree))
+  for (iter = tree;
+       iter != NULL;
+       iter = gtk_css_selector_tree_get_sibling (iter))
     {
       GtkCssChange child_change = 0;
-      gtk_css_selector_tree_match (tree, filter, FALSE, node, &results, change ? &child_change : NULL);
+      gtk_css_selector_tree_match (iter, filter, FALSE, node, &results, change ? &child_change : NULL);
       if (change)
         *change |= child_change;
     }
@@ -1983,7 +1988,7 @@ _gtk_css_selector_tree_is_empty (const GtkCssSelectorTree *tree)
 
 #ifdef PRINT_TREE
 static void
-_gtk_css_selector_tree_print (const GtkCssSelectorTree *tree, GString *str, char *prefix)
+_gtk_css_selector_tree_print (const GtkCssSelectorTree *tree, GString *str, const char *prefix)
 {
   gboolean first = TRUE;
   int len, i;