Imported Upstream version 3.4.0

[platform/upstream/harfbuzz.git] / src / hb-null.hh

diff --git a/src/hb-null.hh b/src/hb-null.hh
index 9853939..db38a4d 100644 (file)
--- a/src/hb-null.hh
+++ b/src/hb-null.hh
@@ -39,8 +39,11 @@
 
 #define HB_NULL_POOL_SIZE 384
 
-/* Use SFINAE to sniff whether T has min_size; in which case return T::null_size,
- * otherwise return sizeof(T). */
+/* Use SFINAE to sniff whether T has min_size; in which case return the larger
+ * of sizeof(T) and T::null_size, otherwise return sizeof(T).
+ *
+ * The main purpose of this is to let structs communicate that they are not nullable,
+ * by defining min_size but *not* null_size. */
 
 /* The hard way...
  * https://stackoverflow.com/questions/7776448/sfinae-tried-with-bool-gives-compiler-error-template-argument-tvalue-invol
@@ -49,8 +52,9 @@
 template <typename T, typename>
 struct _hb_null_size : hb_integral_constant<unsigned, sizeof (T)> {};
 template <typename T>
-struct _hb_null_size<T, hb_void_t<decltype (T::min_size)>> : hb_integral_constant<unsigned, T::null_size> {};
-
+struct _hb_null_size<T, hb_void_t<decltype (T::min_size)>>
+       : hb_integral_constant<unsigned,
+                              (sizeof (T) > T::null_size ? sizeof (T) : T::null_size)> {};
 template <typename T>
 using hb_null_size = _hb_null_size<T, void>;
 #define hb_null_size(T) hb_null_size<T>::value
@@ -68,6 +72,14 @@ template <typename T>
 using hb_static_size = _hb_static_size<T, void>;
 #define hb_static_size(T) hb_static_size<T>::value
 
+template <typename T, typename>
+struct _hb_min_size : hb_integral_constant<unsigned, sizeof (T)> {};
+template <typename T>
+struct _hb_min_size<T, hb_void_t<decltype (T::min_size)>> : hb_integral_constant<unsigned, T::min_size> {};
+template <typename T>
+using hb_min_size = _hb_min_size<T, void>;
+#define hb_min_size(T) hb_min_size<T>::value
+
 
 /*
  * Null()
@@ -177,6 +189,7 @@ struct hb_nonnull_ptr_t
   T * get () const { return v ? v : const_cast<T *> (&Null (T)); }
   T * get_raw () const { return v; }
 
+  private:
   T *v;
 };