[gtk/matthiasc/css-change-tracking-2: 2/3] css: Don't got to the selector tree for change

[Matthias Clasen <matthiasc src gnome org>]

commit 32099766e4f9e8390a48ca9c3bb42fe06c2c9895
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jan 15 08:03:09 2020 -0500

    css: Don't got to the selector tree for change
    
    The tree is optimized for mimizing the decisions, and
    that prevents us from taking advantage of the more exact
    superset matching that we can do now. So, instead do what
    we used to do for verifiation: use the tree for finding the
    superset matches, then just walk the rulesets to collect the
    changes.

 gtk/gtkcssprovider.c | 94 ++++++++++++++++++----------------------------------
 1 file changed, 33 insertions(+), 61 deletions(-)
---
diff --git a/gtk/gtkcssprovider.c b/gtk/gtkcssprovider.c
index 3713b83529..59573ebb34 100644
--- a/gtk/gtkcssprovider.c
+++ b/gtk/gtkcssprovider.c
@@ -425,61 +425,40 @@ verify_tree_match_results (GtkCssProvider *provider,
 #endif
 }
 
-static void
-verify_tree_get_change_results (GtkCssProvider *provider,
-                               const GtkCssMatcher *matcher,
-                               GtkCssChange change)
+/* Compute the change flags for a given matcher.
+ * We assume that name, id and classes stay unchanged, and look for all rules
+ * that can be matched if anything else changes. We collect the change masks
+ * from the selectors of these rules.
+ */
+static GtkCssChange
+compute_change (GtkCssProvider      *provider,
+                const GtkCssMatcher *matcher)
 {
-#ifdef VERIFY_TREE
-  {
-    GtkCssProviderPrivate *priv = gtk_css_provider_get_instance_private (provider);
-    GtkCssChange verify_change = 0;
-    GPtrArray *tree_rules;
-    int i;
-
-    tree_rules = _gtk_css_selector_tree_match_all (priv->tree, matcher);
-    if (tree_rules)
-      {
-        verify_tree_match_results (provider, matcher, tree_rules);
-
-        for (i = tree_rules->len - 1; i >= 0; i--)
-          {
-           GtkCssRuleset *ruleset;
-
-            ruleset = tree_rules->pdata[i];
-
-            verify_change |= _gtk_css_selector_get_change (ruleset->selector);
-          }
-
-        g_ptr_array_free (tree_rules, TRUE);
-      }
-
-    if (change != verify_change)
-      {
-       GString *s;
-
-       s = g_string_new ("");
-       g_string_append (s, "expected change ");
-        gtk_css_change_print (verify_change, s);
-        g_string_append (s, ", but it was ");
-        gtk_css_change_print (change, s);
-       if ((change & ~verify_change) != 0)
-          {
-           g_string_append (s, ", unexpectedly set: ");
-            gtk_css_change_print (change & ~verify_change, s);
-          }
-       if ((~change & verify_change) != 0)
-          {
-           g_string_append_printf (s, ", unexpectedly not set: ");
-            gtk_css_change_print (~change & verify_change, s);
-          }
-       g_warning (s->str);
-       g_string_free (s, TRUE);
-      }
-  }
-#endif
-}
+  GtkCssProviderPrivate *priv = gtk_css_provider_get_instance_private (provider);
+  GtkCssChange change = 0;
+  GPtrArray *tree_rules;
+  int i;
+  GtkCssMatcher change_matcher;
+
+  _gtk_css_matcher_superset_init (&change_matcher, matcher, GTK_CSS_CHANGE_NAME | GTK_CSS_CHANGE_CLASS);
 
+  tree_rules = _gtk_css_selector_tree_match_all (priv->tree, &change_matcher);
+  if (tree_rules)
+    {
+      for (i = tree_rules->len - 1; i >= 0; i--)
+        {
+         GtkCssRuleset *ruleset;
+
+          ruleset = tree_rules->pdata[i];
+
+          change |= _gtk_css_selector_get_change (ruleset->selector);
+        }
+
+      g_ptr_array_free (tree_rules, TRUE);
+   }
+
+  return change;
+}
 
 static GtkCssValue *
 gtk_css_style_provider_get_color (GtkStyleProvider *provider,
@@ -551,14 +530,7 @@ gtk_css_style_provider_lookup (GtkStyleProvider    *provider,
     }
 
   if (change)
-    {
-      GtkCssMatcher change_matcher;
-
-      _gtk_css_matcher_superset_init (&change_matcher, matcher, GTK_CSS_CHANGE_NAME | GTK_CSS_CHANGE_CLASS);
-
-      *change = _gtk_css_selector_tree_get_change_all (priv->tree, &change_matcher);
-      verify_tree_get_change_results (css_provider, &change_matcher, *change);
-    }
+    *change = compute_change (css_provider, matcher);
 }
 
 static void