diff --git a/src/hb-object-private.hh b/src/hb-object-private.hh
index 7bc6b46d7..d124758fc 100644
--- a/src/hb-object-private.hh
+++ b/src/hb-object-private.hh
@@ -44,134 +44,28 @@ HB_BEGIN_DECLS
 #endif
 
 
+/* reference_count */
+
+typedef struct {
+  hb_atomic_int_t ref_count;
+
+#define HB_REFERENCE_COUNT_INVALID_VALUE ((hb_atomic_int_t) -1)
+#define HB_REFERENCE_COUNT_INVALID {HB_REFERENCE_COUNT_INVALID_VALUE}
+
+  inline void init (int v) { ref_count = v; /* non-atomic is fine */ }
+  inline int inc (void) { return hb_atomic_int_fetch_and_add (ref_count,  1); }
+  inline int dec (void) { return hb_atomic_int_fetch_and_add (ref_count, -1); }
+  inline void set (int v) { hb_atomic_int_set (ref_count, v); }
+
+  inline int get (void) const { return hb_atomic_int_get (ref_count); }
+  inline bool is_invalid (void) const { return get () == HB_REFERENCE_COUNT_INVALID_VALUE; }
+
+} hb_reference_count_t;
+
+
 /* user_data */
 
-HB_END_DECLS
-
-
-template <typename Type, unsigned int StaticSize>
-struct hb_static_array_t {
-
-  unsigned int len;
-  unsigned int allocated;
-  Type *array;
-  Type static_array[StaticSize];
-
-  void finish (void) { for (unsigned i = 0; i < len; i++) array[i].finish (); }
-
-  inline Type& operator [] (unsigned int i)
-  {
-    return array[i];
-  }
-
-  inline Type *push (void)
-  {
-    if (!array) {
-      array = static_array;
-      allocated = ARRAY_LENGTH (static_array);
-    }
-    if (likely (len < allocated))
-      return &array[len++];
-    /* Need to reallocate */
-    unsigned int new_allocated = allocated + (allocated >> 1) + 8;
-    Type *new_array;
-    if (array == static_array) {
-      new_array = (Type *) calloc (new_allocated, sizeof (Type));
-      if (new_array) {
-        memcpy (new_array, array, len * sizeof (Type));
-	array = new_array;
-      }
-    } else {
-      bool overflows = new_allocated >= ((unsigned int) -1) / sizeof (Type);
-      if (unlikely (overflows))
-        new_array = NULL;
-      else
-	new_array = (Type *) realloc (array, new_allocated * sizeof (Type));
-      if (new_array) {
-        free (array);
-	array = new_array;
-      }
-    }
-    if ((len < allocated))
-      return &array[len++];
-    else
-      return NULL;
-  }
-
-  inline void pop (void)
-  {
-    len--;
-    /* TODO: shrink array if needed */
-  }
-};
-
-template <typename Type>
-struct hb_array_t : hb_static_array_t<Type, 2> {};
-
-
-template <typename Key, typename Value>
-struct hb_map_t
-{
-  struct item_t {
-    Key key;
-    /* unsigned int hash; */
-    Value value;
-
-    void finish (void) { value.finish (); }
-  };
-
-  hb_array_t <item_t> items;
-
-  private:
-
-  inline item_t *find (Key key) {
-    if (unlikely (!key)) return NULL;
-    for (unsigned int i = 0; i < items.len; i++)
-      if (key == items[i].key)
-	return &items[i];
-    return NULL;
-  }
-
-  public:
-
-  inline bool set (Key   key,
-		   Value &value)
-  {
-    if (unlikely (!key)) return NULL;
-    item_t *item;
-    item = find (key);
-    if (item)
-      item->finish ();
-    else
-      item = items.push ();
-    if (unlikely (!item)) return false;
-    item->key = key;
-    item->value = value;
-    return true;
-  }
-
-  inline void unset (Key &key)
-  {
-    item_t *item;
-    item = find (key);
-    if (!item) return;
-
-    item->finish ();
-    items[items.len - 1] = *item;
-    items.pop ();
-  }
-
-  inline Value *get (Key key)
-  {
-    item_t *item = find (key);
-    return item ? &item->value : NULL;
-  }
-
-  void finish (void) { items.finish (); }
-};
-
-
-HB_BEGIN_DECLS
+/* XXX make this thread-safe, somehow! */
 
 typedef struct {
   void *data;
@@ -204,6 +98,7 @@ struct hb_user_data_array_t {
 };
 
 
+/* object_header */
 
 typedef struct _hb_object_header_t hb_object_header_t;
 
@@ -273,6 +168,9 @@ struct _hb_object_header_t {
 
 HB_END_DECLS
 
+
+/* object */
+
 template <typename Type>
 static inline void hb_object_trace (const Type *obj, const char *function)
 {
@@ -303,6 +201,21 @@ static inline bool hb_object_destroy (Type *obj)
   hb_object_trace (obj, HB_FUNC);
   return obj->header.destroy ();
 }
+template <typename Type>
+static inline bool hb_object_set_user_data (Type               *obj,
+					    hb_user_data_key_t *key,
+					    void *              data,
+					    hb_destroy_func_t   destroy)
+{
+  return obj->header.set_user_data (key, data, destroy);
+}
+
+template <typename Type>
+static inline void *hb_object_get_user_data (Type               *obj,
+					     hb_user_data_key_t *key)
+{
+  return obj->header.get_user_data (key);
+}
 
 
 HB_BEGIN_DECLS
diff --git a/src/hb-private.hh b/src/hb-private.hh
index fc06e7056..ce09d1825 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -258,23 +258,135 @@ typedef volatile int hb_mutex_t;
 #endif
 
 
-/* A reference count */
+HB_END_DECLS
 
-typedef struct {
-  hb_atomic_int_t ref_count;
 
-#define HB_REFERENCE_COUNT_INVALID_VALUE ((hb_atomic_int_t) -1)
-#define HB_REFERENCE_COUNT_INVALID {HB_REFERENCE_COUNT_INVALID_VALUE}
+/* arrays and maps */
 
-  inline void init (int v) { ref_count = v; /* non-atomic is fine */ }
-  inline int inc (void) { return hb_atomic_int_fetch_and_add (ref_count,  1); }
-  inline int dec (void) { return hb_atomic_int_fetch_and_add (ref_count, -1); }
-  inline void set (int v) { hb_atomic_int_set (ref_count, v); }
 
-  inline int get (void) const { return hb_atomic_int_get (ref_count); }
-  inline bool is_invalid (void) const { return get () == HB_REFERENCE_COUNT_INVALID_VALUE; }
+template <typename Type, unsigned int StaticSize>
+struct hb_static_array_t {
 
-} hb_reference_count_t;
+  unsigned int len;
+  unsigned int allocated;
+  Type *array;
+  Type static_array[StaticSize];
+
+  void finish (void) { for (unsigned i = 0; i < len; i++) array[i].finish (); }
+
+  inline Type& operator [] (unsigned int i)
+  {
+    return array[i];
+  }
+
+  inline Type *push (void)
+  {
+    if (!array) {
+      array = static_array;
+      allocated = ARRAY_LENGTH (static_array);
+    }
+    if (likely (len < allocated))
+      return &array[len++];
+    /* Need to reallocate */
+    unsigned int new_allocated = allocated + (allocated >> 1) + 8;
+    Type *new_array;
+    if (array == static_array) {
+      new_array = (Type *) calloc (new_allocated, sizeof (Type));
+      if (new_array) {
+        memcpy (new_array, array, len * sizeof (Type));
+	array = new_array;
+      }
+    } else {
+      bool overflows = new_allocated >= ((unsigned int) -1) / sizeof (Type);
+      if (unlikely (overflows))
+        new_array = NULL;
+      else
+	new_array = (Type *) realloc (array, new_allocated * sizeof (Type));
+      if (new_array) {
+        free (array);
+	array = new_array;
+      }
+    }
+    if ((len < allocated))
+      return &array[len++];
+    else
+      return NULL;
+  }
+
+  inline void pop (void)
+  {
+    len--;
+    /* TODO: shrink array if needed */
+  }
+};
+
+template <typename Type>
+struct hb_array_t : hb_static_array_t<Type, 2> {};
+
+
+template <typename Key, typename Value>
+struct hb_map_t
+{
+  struct item_t {
+    Key key;
+    /* unsigned int hash; */
+    Value value;
+
+    void finish (void) { value.finish (); }
+  };
+
+  hb_array_t <item_t> items;
+
+  private:
+
+  inline item_t *find (Key key) {
+    if (unlikely (!key)) return NULL;
+    for (unsigned int i = 0; i < items.len; i++)
+      if (key == items[i].key)
+	return &items[i];
+    return NULL;
+  }
+
+  public:
+
+  inline bool set (Key   key,
+		   Value &value)
+  {
+    if (unlikely (!key)) return NULL;
+    item_t *item;
+    item = find (key);
+    if (item)
+      item->finish ();
+    else
+      item = items.push ();
+    if (unlikely (!item)) return false;
+    item->key = key;
+    item->value = value;
+    return true;
+  }
+
+  inline void unset (Key &key)
+  {
+    item_t *item;
+    item = find (key);
+    if (!item) return;
+
+    item->finish ();
+    items[items.len - 1] = *item;
+    items.pop ();
+  }
+
+  inline Value *get (Key key)
+  {
+    item_t *item = find (key);
+    return item ? &item->value : NULL;
+  }
+
+  void finish (void) { items.finish (); }
+};
+
+
+HB_BEGIN_DECLS
 
 
 /* Big-endian handling */