Fix attr iterators with overlapping attributesfix-nested-attributes

This broke when PangoAttrIterator was changed to
use an array for the stack of current attributes, in
dec6c0868ef2c36. We were not always walking the array
in the right order. The first attribute to check is
at the *end* of the array.

This showed up as misrendering in epsilon_0 example
in gtk3-demo's text view markup demo.

Test included.

2 files changed, 95 insertions, 11 deletions

diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index 12942043..4f96135b 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -2003,7 +2003,7 @@ pango_attr_iterator_range (PangoAttrIterator *iterator,
 gboolean
 pango_attr_iterator_next (PangoAttrIterator *iterator)
 {
-  guint i;
+  int i;
 
   g_return_val_if_fail (iterator != NULL, FALSE);
 
@@ -2016,19 +2016,14 @@ pango_attr_iterator_next (PangoAttrIterator *iterator)
 
   if (iterator->attribute_stack)
     {
-      for (i = 0; i < iterator->attribute_stack->len; i++)
+      for (i = iterator->attribute_stack->len - 1; i>= 0; i--)
         {
           const PangoAttribute *attr = g_ptr_array_index (iterator->attribute_stack, i);
 
           if (attr->end_index == iterator->start_index)
-            {
-              g_ptr_array_remove_index (iterator->attribute_stack, i); /* Can't use index_fast :( */;
-              i--;
-            }
+            g_ptr_array_remove_index (iterator->attribute_stack, i); /* Can't use index_fast :( */
           else
-            {
-              iterator->end_index = MIN (iterator->end_index, attr->end_index);
-            }
+            iterator->end_index = MIN (iterator->end_index, attr->end_index);
         }
     }
 
@@ -2136,14 +2131,14 @@ PangoAttribute *
 pango_attr_iterator_get (PangoAttrIterator *iterator,
 			 PangoAttrType      type)
 {
-  guint i;
+  int i;
 
   g_return_val_if_fail (iterator != NULL, NULL);
 
   if (!iterator->attribute_stack)
     return NULL;
 
-  for (i = 0; i < iterator->attribute_stack->len; i++)
+  for (i = iterator->attribute_stack->len - 1; i>= 0; i--)
     {
       PangoAttribute *attr = g_ptr_array_index (iterator->attribute_stack, i);
 
diff --git a/tests/testattributes.c b/tests/testattributes.c
index 8db42b4a..6131f38c 100644
--- a/tests/testattributes.c
+++ b/tests/testattributes.c
@@ -944,6 +944,94 @@ test_merge2 (void)
   pango_attr_list_unref (list);
 }
 
+/* This only prints rise, size and scale, which are the
+ * only relevant attributes in the test that uses this
+ * function.
+ */
+static void
+print_tags_for_attributes (PangoAttrIterator *iter,
+                           GString           *s)
+{
+  PangoAttribute *attr;
+
+  attr = pango_attr_iterator_get (iter, PANGO_ATTR_RISE);
+  if (attr)
+    g_string_append_printf (s, "[%d, %d]rise=%d\n",
+                            attr->start_index, attr->end_index,
+                            ((PangoAttrInt*)attr)->value);
+
+  attr = pango_attr_iterator_get (iter, PANGO_ATTR_SIZE);
+  if (attr)
+    g_string_append_printf (s, "[%d, %d]size=%d\n",
+                            attr->start_index, attr->end_index,
+                            ((PangoAttrInt*)attr)->value);
+
+  attr = pango_attr_iterator_get (iter, PANGO_ATTR_SCALE);
+  if (attr)
+    g_string_append_printf (s, "[%d, %d]scale=%f\n",
+                            attr->start_index, attr->end_index,
+                            ((PangoAttrFloat*)attr)->value);
+}
+
+static void
+test_iter_epsilon_zero (void)
+{
+  const char *markup = "𝜀<span rise=\"-6000\" size=\"x-small\" font_desc=\"italic\">0</span> = 𝜔<span rise=\"8000\" size=\"smaller\">𝜔<span rise=\"14000\" size=\"smaller\">𝜔<span rise=\"20000\">.<span rise=\"23000\">.<span rise=\"26000\">.</span></span></span></span></span>";
+  PangoAttrList *attributes;
+  PangoAttrIterator *attr;
+  char *text;
+  GError *error = NULL;
+  GString *s;
+
+  s = g_string_new ("");
+
+  pango_parse_markup (markup, -1, 0, &attributes, &text, NULL, &error);
+  g_assert_no_error (error);
+  g_assert_cmpstr (text, ==, "𝜀0 = 𝜔𝜔𝜔...");
+
+  attr = pango_attr_list_get_iterator (attributes);
+  do
+    {
+      int start, end;
+
+      pango_attr_iterator_range (attr, &start, &end);
+
+      g_string_append_printf (s, "range: [%d, %d]\n", start, end);
+
+      print_tags_for_attributes (attr, s);
+    }
+  while (pango_attr_iterator_next (attr));
+
+  g_assert_cmpstr (s->str, ==,
+                   "range: [0, 4]\n"
+                   "range: [4, 5]\n"
+                   "[4, 5]rise=-6000\n"
+                   "[4, 5]scale=0.694444\n"
+                   "range: [5, 12]\n"
+                   "range: [12, 16]\n"
+                   "[12, 23]rise=8000\n"
+                   "[12, 23]scale=0.833333\n"
+                   "range: [16, 20]\n"
+                   "[16, 23]rise=14000\n"
+                   "[16, 23]scale=0.694444\n"
+                   "range: [20, 21]\n"
+                   "[20, 23]rise=20000\n"
+                   "[16, 23]scale=0.694444\n"
+                   "range: [21, 22]\n"
+                   "[21, 23]rise=23000\n"
+                   "[16, 23]scale=0.694444\n"
+                   "range: [22, 23]\n"
+                   "[22, 23]rise=26000\n"
+                   "[16, 23]scale=0.694444\n"
+                   "range: [23, 2147483647]\n");
+
+  g_free (text);
+  pango_attr_list_unref (attributes);
+  pango_attr_iterator_destroy (attr);
+
+  g_string_free (s, TRUE);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -966,6 +1054,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/attributes/iter/get", test_iter_get);
   g_test_add_func ("/attributes/iter/get_font", test_iter_get_font);
   g_test_add_func ("/attributes/iter/get_attrs", test_iter_get_attrs);
+  g_test_add_func ("/attributes/iter/epsilon_zero", test_iter_epsilon_zero);
 
   return g_test_run ();
 }