diff --git a/src/hb-ot-layout-common.hh b/src/hb-ot-layout-common.hh
index a82e2d95d..ab4b40d1c 100644
--- a/src/hb-ot-layout-common.hh
+++ b/src/hb-ot-layout-common.hh
@@ -1587,6 +1587,82 @@ static inline void ClassDef_serialize (hb_serialize_context_t *c,
 				       hb_array_t<const HBUINT16> klasses)
 { c->start_embed<ClassDef> ()->serialize (c, glyphs, klasses); }
 
+struct hb_map2_t
+{
+  hb_map2_t () { init (); }
+  ~hb_map2_t () { fini (); }
+
+  void init (void)
+  {
+    count = 0;
+    old_to_new_map.init ();
+    new_to_old_map.init ();
+    set.init ();
+  }
+
+  void fini (void)
+  {
+    old_to_new_map.fini ();
+    new_to_old_map.fini ();
+    set.fini ();
+  }
+
+  bool has (hb_codepoint_t id) const { return set.has (id); }
+
+  hb_codepoint_t add (hb_codepoint_t i)
+  {
+    hb_codepoint_t	v = old_to_new_map[i];
+    if (v == HB_MAP_VALUE_INVALID)
+    {
+      set.add (i);
+      v = count++;
+      old_to_new_map.set (i, v);
+      new_to_old_map.set (v, i);
+    }
+    return v;
+  }
+
+  /* returns HB_MAP_VALUE_INVALID if unmapped */
+  hb_codepoint_t operator [] (hb_codepoint_t i) const { return old_to_new (i); }
+  hb_codepoint_t old_to_new (hb_codepoint_t i) const { return old_to_new_map[i]; }
+  hb_codepoint_t new_to_old (hb_codepoint_t i) const { return new_to_old_map[i]; }
+
+  bool identity (unsigned int size)
+  {
+    hb_codepoint_t i;
+    old_to_new_map.clear ();
+    new_to_old_map.clear ();
+    set.clear ();
+    for (i = 0; i < size; i++)
+    {
+      old_to_new_map.set (i, i);
+      new_to_old_map.set (i, i);
+      set.add (i);
+    }
+    count = i;
+    return old_to_new_map.successful && new_to_old_map.successful && set.successful;
+  }
+
+  /* Optional: after finished adding all mappings in a random order,
+   * reorder outputs in the same order as the inputs. */
+  void reorder (void)
+  {
+    for (hb_codepoint_t	i = HB_SET_VALUE_INVALID, count = 0; set.next (&i); count++)
+    {
+       new_to_old_map.set (count, i);
+       old_to_new_map.set (i, count);
+    }
+  }
+
+  unsigned int get_count () const { return count; }
+  unsigned int get_bits () const { return count? hb_bit_storage (count - 1): 0; }
+
+  protected:
+  unsigned int  count;
+  hb_map_t	old_to_new_map;
+  hb_map_t	new_to_old_map;
+  hb_set_t	set;
+};
 
 /*
  * Item Variation Store
@@ -1755,7 +1831,7 @@ struct VarData
     if (unlikely (!c->extend_min (*this))) return_trace (false);
     itemCount.set (remap.get_count ());
     shortCount.set (src->shortCount);
-    
+
     unsigned int row_size = src->get_row_size ();
     if (unlikely (!c->allocate_size<HBUINT8> (src->regionIndices.get_size () + (row_size * remap.get_count ()))))
       return_trace (false);
@@ -1841,7 +1917,7 @@ struct VariationStore
 		      .serialize (c, &(src+src->dataSets[i]), inner_remaps[i])))
       	return_trace (false);
     }
-    
+
     return_trace (true);
   }
 
@@ -2242,7 +2318,6 @@ struct Device
   DEFINE_SIZE_UNION (6, b);
 };
 
-
 } /* namespace OT */
 
 
diff --git a/src/hb-ot-var-hvar-table.hh b/src/hb-ot-var-hvar-table.hh
index 97e70605c..e9768f3f1 100644
--- a/src/hb-ot-var-hvar-table.hh
+++ b/src/hb-ot-var-hvar-table.hh
@@ -159,7 +159,7 @@ struct index_map_subset_plan_t
 	continue;
       }
       if (v != last_val) break;
-  
+
       last_gid = gid;
     }