[subset-input] Refactor copy-pasta code

src/hb-subset-input.cc

@@ -482,37 +482,26 @@ hb_subset_preprocess (hb_face_t *source)
   if (!input)
     return hb_face_reference (source);
 
-  hb_set_clear (hb_subset_input_set(input, HB_SUBSET_SETS_UNICODE));
-  hb_set_invert (hb_subset_input_set(input, HB_SUBSET_SETS_UNICODE));
-
-  hb_set_clear (hb_subset_input_set(input, HB_SUBSET_SETS_GLYPH_INDEX));
-  hb_set_invert (hb_subset_input_set(input, HB_SUBSET_SETS_GLYPH_INDEX));
-
-  hb_set_clear (hb_subset_input_set(input,
-                                    HB_SUBSET_SETS_LAYOUT_FEATURE_TAG));
-  hb_set_invert (hb_subset_input_set(input,
-                                     HB_SUBSET_SETS_LAYOUT_FEATURE_TAG));
-
-  hb_set_clear (hb_subset_input_set(input,
-                                    HB_SUBSET_SETS_LAYOUT_SCRIPT_TAG));
-  hb_set_invert (hb_subset_input_set(input,
-                                     HB_SUBSET_SETS_LAYOUT_SCRIPT_TAG));
-
-  hb_set_clear (hb_subset_input_set(input,
-                                    HB_SUBSET_SETS_NAME_ID));
-  hb_set_invert (hb_subset_input_set(input,
-                                     HB_SUBSET_SETS_NAME_ID));
-
-  hb_set_clear (hb_subset_input_set(input,
-                                    HB_SUBSET_SETS_NAME_LANG_ID));
-  hb_set_invert (hb_subset_input_set(input,
-                                     HB_SUBSET_SETS_NAME_LANG_ID));
+  const hb_subset_sets_t indices[] = {HB_SUBSET_SETS_UNICODE,
+				      HB_SUBSET_SETS_GLYPH_INDEX,
+				      HB_SUBSET_SETS_NAME_ID,
+				      HB_SUBSET_SETS_NAME_LANG_ID,
+				      HB_SUBSET_SETS_LAYOUT_FEATURE_TAG,
+				      HB_SUBSET_SETS_LAYOUT_SCRIPT_TAG};
+
+  for (auto idx : hb_iter (indices))
+  {
+    hb_set_t *set = hb_subset_input_set (input, idx);
+    hb_set_clear (set);
+    hb_set_invert (set);
+  }
 
   hb_subset_input_set_flags(input,
                             HB_SUBSET_FLAGS_NOTDEF_OUTLINE |
                             HB_SUBSET_FLAGS_GLYPH_NAMES |
                             HB_SUBSET_FLAGS_RETAIN_GIDS |
                             HB_SUBSET_FLAGS_NO_PRUNE_UNICODE_RANGES);
+
   input->attach_accelerator_data = true;
 
   // Always use long loca in the preprocessed version. This allows