Port _nil objects to Null() machinery

Finally, unified!

src/hb-blob-private.hh

@@ -76,6 +76,7 @@ struct hb_blob_t
   void *user_data;
   hb_destroy_func_t destroy;
 };
+DECLARE_NULL_INSTANCE (hb_blob_t);
 
 
 #endif /* HB_BLOB_PRIVATE_HH */

src/hb-blob.cc

@@ -45,6 +45,20 @@
 #include <stdlib.h>
 
 
+DEFINE_NULL_INSTANCE (hb_blob_t) =
+{
+  HB_OBJECT_HEADER_STATIC,
+
+  true, /* immutable */
+
+  nullptr, /* data */
+  0, /* length */
+  HB_MEMORY_MODE_READONLY, /* mode */
+
+  nullptr, /* user_data */
+  nullptr  /* destroy */
+};
+
 /**
  * hb_blob_create: (skip)
  * @data: Pointer to blob data.
@@ -182,20 +196,7 @@ hb_blob_copy_writable_or_fail (hb_blob_t *blob)
 hb_blob_t *
 hb_blob_get_empty (void)
 {
-  static const hb_blob_t _hb_blob_nil = {
-    HB_OBJECT_HEADER_STATIC,
-
-    true, /* immutable */
-
-    nullptr, /* data */
-    0, /* length */
-    HB_MEMORY_MODE_READONLY, /* mode */
-
-    nullptr, /* user_data */
-    nullptr  /* destroy */
-  };
-
-  return const_cast<hb_blob_t *> (&_hb_blob_nil);
+  return const_cast<hb_blob_t *> (&Null(hb_blob_t));
 }
 
 /**

src/hb-buffer-private.hh

@@ -83,7 +83,8 @@ HB_MARK_AS_FLAG_T (hb_buffer_scratch_flags_t);
  * hb_buffer_t
  */
 
-struct hb_buffer_t {
+struct hb_buffer_t
+{
   hb_object_header_t header;
   ASSERT_POD ();
 
@@ -352,6 +353,7 @@ struct hb_buffer_t {
       info[i].mask &= ~HB_GLYPH_FLAG_UNSAFE_TO_BREAK;
   }
 };
+DECLARE_NULL_INSTANCE (hb_buffer_t);
 
 
 /* Loop over clusters. Duplicated in foreach_syllable(). */

src/hb-buffer.cc

@@ -701,6 +701,28 @@ hb_buffer_t::guess_segment_properties (void)
 
 /* Public API */
 
+DEFINE_NULL_INSTANCE (hb_buffer_t) =
+{
+  HB_OBJECT_HEADER_STATIC,
+
+  const_cast<hb_unicode_funcs_t *> (&_hb_Null_hb_unicode_funcs_t),
+  HB_BUFFER_FLAG_DEFAULT,
+  HB_BUFFER_CLUSTER_LEVEL_DEFAULT,
+  HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT,
+  HB_BUFFER_SCRATCH_FLAG_DEFAULT,
+  HB_BUFFER_MAX_LEN_DEFAULT,
+  HB_BUFFER_MAX_OPS_DEFAULT,
+
+  HB_BUFFER_CONTENT_TYPE_INVALID,
+  HB_SEGMENT_PROPERTIES_DEFAULT,
+  false, /* successful */
+  true, /* have_output */
+  true  /* have_positions */
+
+  /* Zero is good enough for everything else. */
+};
+
+
 /**
  * hb_buffer_create: (Xconstructor)
  *
@@ -743,27 +765,7 @@ hb_buffer_create (void)
 hb_buffer_t *
 hb_buffer_get_empty (void)
 {
-  static const hb_buffer_t _hb_buffer_nil = {
-    HB_OBJECT_HEADER_STATIC,
-
-    const_cast<hb_unicode_funcs_t *> (&_hb_unicode_funcs_nil),
-    HB_BUFFER_FLAG_DEFAULT,
-    HB_BUFFER_CLUSTER_LEVEL_DEFAULT,
-    HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT,
-    HB_BUFFER_SCRATCH_FLAG_DEFAULT,
-    HB_BUFFER_MAX_LEN_DEFAULT,
-    HB_BUFFER_MAX_OPS_DEFAULT,
-
-    HB_BUFFER_CONTENT_TYPE_INVALID,
-    HB_SEGMENT_PROPERTIES_DEFAULT,
-    false, /* successful */
-    true, /* have_output */
-    true  /* have_positions */
-
-    /* Zero is good enough for everything else. */
-  };
-
-  return const_cast<hb_buffer_t *> (&_hb_buffer_nil);
+  return const_cast<hb_buffer_t *> (&Null(hb_buffer_t));
 }
 
 /**

src/hb-face-private.hh

@@ -39,7 +39,8 @@
  * hb_face_t
  */
 
-struct hb_face_t {
+struct hb_face_t
+{
   hb_object_header_t header;
   ASSERT_POD ();
 
@@ -94,8 +95,7 @@ struct hb_face_t {
   HB_INTERNAL void load_upem (void) const;
   HB_INTERNAL void load_num_glyphs (void) const;
 };
-
-extern HB_INTERNAL const hb_face_t _hb_face_nil;
+DECLARE_NULL_INSTANCE (hb_face_t);
 
 #define HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS
 #define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_PROTOTYPE(shaper, face);

src/hb-face.cc

@@ -63,7 +63,8 @@ hb_face_count (hb_blob_t *blob)
  * hb_face_t
  */
 
-const hb_face_t _hb_face_nil = {
+DEFINE_NULL_INSTANCE (hb_face_t) =
+{
   HB_OBJECT_HEADER_STATIC,
 
   true, /* immutable */
@@ -215,7 +216,7 @@ hb_face_create (hb_blob_t    *blob,
 hb_face_t *
 hb_face_get_empty (void)
 {
-  return const_cast<hb_face_t *> (&_hb_face_nil);
+  return const_cast<hb_face_t *> (&Null(hb_face_t));
 }
 
 

src/hb-font-private.hh

@@ -35,7 +35,6 @@
 #include "hb-shaper-private.hh"
 
 
-
 /*
  * hb_font_funcs_t
  */
@@ -57,7 +56,8 @@
   HB_FONT_FUNC_IMPLEMENT (glyph_from_name) \
   /* ^--- Add new callbacks here */
 
-struct hb_font_funcs_t {
+struct hb_font_funcs_t
+{
   hb_object_header_t header;
   ASSERT_POD ();
 
@@ -89,14 +89,15 @@ struct hb_font_funcs_t {
 		]) (void);
   } get;
 };
-
+DECLARE_NULL_INSTANCE (hb_font_funcs_t);
 
 
 /*
  * hb_font_t
  */
 
-struct hb_font_t {
+struct hb_font_t
+{
   hb_object_header_t header;
   ASSERT_POD ();
 
@@ -553,6 +554,7 @@ struct hb_font_t {
     return (float) v * scale / face->get_upem ();
   }
 };
+DECLARE_NULL_INSTANCE (hb_font_t);
 
 #define HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS
 #define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_PROTOTYPE(shaper, font);

src/hb-font.cc

@@ -341,7 +341,8 @@ hb_font_get_glyph_from_name_parent (hb_font_t *font,
   return font->parent->get_glyph_from_name (name, len, glyph);
 }
 
-static const hb_font_funcs_t _hb_font_funcs_nil = {
+DEFINE_NULL_INSTANCE (hb_font_funcs_t) =
+{
   HB_OBJECT_HEADER_STATIC,
 
   true, /* immutable */
@@ -364,6 +365,7 @@ static const hb_font_funcs_t _hb_font_funcs_nil = {
     }
   }
 };
+
 static const hb_font_funcs_t _hb_font_funcs_parent = {
   HB_OBJECT_HEADER_STATIC,
 
@@ -1100,6 +1102,37 @@ hb_font_glyph_from_string (hb_font_t *font,
  * hb_font_t
  */
 
+DEFINE_NULL_INSTANCE (hb_font_t) =
+{
+  HB_OBJECT_HEADER_STATIC,
+
+  true, /* immutable */
+
+  nullptr, /* parent */
+  const_cast<hb_face_t *> (&_hb_Null_hb_face_t),
+
+  1000, /* x_scale */
+  1000, /* y_scale */
+
+  0, /* x_ppem */
+  0, /* y_ppem */
+  0, /* ptem */
+
+  0, /* num_coords */
+  nullptr, /* coords */
+
+  const_cast<hb_font_funcs_t *> (&_hb_Null_hb_font_funcs_t), /* klass */
+  nullptr, /* user_data */
+  nullptr, /* destroy */
+
+  {
+#define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_INVALID,
+#include "hb-shaper-list.hh"
+#undef HB_SHAPER_IMPLEMENT
+  }
+};
+
+
 /**
  * hb_font_create: (Xconstructor)
  * @face: a face.
@@ -1187,36 +1220,7 @@ hb_font_create_sub_font (hb_font_t *parent)
 hb_font_t *
 hb_font_get_empty (void)
 {
-  static const hb_font_t _hb_font_nil = {
-    HB_OBJECT_HEADER_STATIC,
-
-    true, /* immutable */
-
-    nullptr, /* parent */
-    const_cast<hb_face_t *> (&_hb_face_nil),
-
-    1000, /* x_scale */
-    1000, /* y_scale */
-
-    0, /* x_ppem */
-    0, /* y_ppem */
-    0, /* ptem */
-
-    0, /* num_coords */
-    nullptr, /* coords */
-
-    const_cast<hb_font_funcs_t *> (&_hb_font_funcs_nil), /* klass */
-    nullptr, /* user_data */
-    nullptr, /* destroy */
-
-    {
-#define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_INVALID,
-#include "hb-shaper-list.hh"
-#undef HB_SHAPER_IMPLEMENT
-    }
-  };
-
-  return const_cast<hb_font_t *> (&_hb_font_nil);
+  return const_cast<hb_font_t *> (&Null(hb_font_t));
 }
 
 /**

src/hb-null.hh

@@ -59,10 +59,19 @@ template <> \
 } \
 namespace Namespace { \
 static_assert (true, "Just so we take semicolon after.")
-
 #define DEFINE_NULL_NAMESPACE_BYTES(Namespace, Type) \
 const unsigned char _hb_Null_##Namespace##_##Type[Namespace::Type::min_size]
 
+/* Specializaitons for arbitrary-content Null objects expressed as struct initializer. */
+#define DECLARE_NULL_INSTANCE(Type) \
+extern HB_INTERNAL const Type _hb_Null_##Type; \
+template <> \
+/*static*/ inline const Type& Null<Type> (void) { \
+  return _hb_Null_##Type; \
+} \
+static_assert (true, "Just so we take semicolon after.")
+#define DEFINE_NULL_INSTANCE(Type) \
+const Type _hb_Null_##Type
 
 /* Global writable pool.  Enlarge as necessary. */
 

src/hb-ot-shape-complex-arabic-fallback.hh

@@ -205,8 +205,6 @@ struct arabic_fallback_plan_t
   hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
 };
 
-static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};
-
 #if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(HB_NO_WIN1256)
 #define HB_WITH_WIN1256
 #endif
@@ -215,7 +213,8 @@ static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};
 #include "hb-ot-shape-complex-arabic-win1256.hh"
 #endif
 
-struct ManifestLookup {
+struct ManifestLookup
+{
   OT::Tag tag;
   OT::OffsetTo<OT::SubstLookup> lookupOffset;
 };
@@ -299,7 +298,7 @@ arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
 {
   arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
   if (unlikely (!fallback_plan))
-    return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
+    return const_cast<arabic_fallback_plan_t *> (&Null(arabic_fallback_plan_t));
 
   fallback_plan->num_lookups = 0;
   fallback_plan->free_lookups = false;
@@ -315,13 +314,13 @@ arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
     return fallback_plan;
 
   free (fallback_plan);
-  return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
+  return const_cast<arabic_fallback_plan_t *> (&Null(arabic_fallback_plan_t));
 }
 
 static void
 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
 {
-  if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)
+  if (!fallback_plan || fallback_plan == &Null(arabic_fallback_plan_t))
     return;
 
   for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)

src/hb-shape-plan-private.hh

@@ -51,6 +51,7 @@ struct hb_shape_plan_t
 
   struct hb_shaper_data_t shaper_data;
 };
+DECLARE_NULL_INSTANCE (hb_shape_plan_t);
 
 #define HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS \
 	, const hb_feature_t *user_features \

src/hb-shape-plan.cc

@@ -88,6 +88,31 @@ hb_shape_plan_plan (hb_shape_plan_t    *shape_plan,
  * hb_shape_plan_t
  */
 
+DEFINE_NULL_INSTANCE (hb_shape_plan_t) =
+{
+  HB_OBJECT_HEADER_STATIC,
+
+  true, /* default_shaper_list */
+  nullptr, /* face */
+  HB_SEGMENT_PROPERTIES_DEFAULT, /* props */
+
+  nullptr, /* shaper_func */
+  nullptr, /* shaper_name */
+
+  nullptr, /* user_features */
+  0,    /* num_user_featurs */
+
+  nullptr, /* coords */
+  0,    /* num_coords */
+
+  {
+#define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_INVALID,
+#include "hb-shaper-list.hh"
+#undef HB_SHAPER_IMPLEMENT
+  }
+};
+
+
 /**
  * hb_shape_plan_create: (Xconstructor)
  * @face: 
@@ -188,30 +213,7 @@ hb_shape_plan_create2 (hb_face_t                     *face,
 hb_shape_plan_t *
 hb_shape_plan_get_empty (void)
 {
-  static const hb_shape_plan_t _hb_shape_plan_nil = {
-    HB_OBJECT_HEADER_STATIC,
-
-    true, /* default_shaper_list */
-    nullptr, /* face */
-    HB_SEGMENT_PROPERTIES_DEFAULT, /* props */
-
-    nullptr, /* shaper_func */
-    nullptr, /* shaper_name */
-
-    nullptr, /* user_features */
-    0,    /* num_user_featurs */
-
-    nullptr, /* coords */
-    0,    /* num_coords */
-
-    {
-#define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_INVALID,
-#include "hb-shaper-list.hh"
-#undef HB_SHAPER_IMPLEMENT
-    }
-  };
-
-  return const_cast<hb_shape_plan_t *> (&_hb_shape_plan_nil);
+  return const_cast<hb_shape_plan_t *> (&Null(hb_shape_plan_t));
 }
 
 /**

src/hb-unicode-private.hh

@@ -60,7 +60,8 @@ extern HB_INTERNAL const uint8_t _hb_modified_combining_class[256];
   HB_UNICODE_FUNC_IMPLEMENT (hb_script_t, script) \
   /* ^--- Add new simple callbacks here */
 
-struct hb_unicode_funcs_t {
+struct hb_unicode_funcs_t
+{
   hb_object_header_t header;
   ASSERT_POD ();
 
@@ -263,9 +264,7 @@ HB_UNICODE_FUNCS_IMPLEMENT_CALLBACKS_SIMPLE
 #undef HB_UNICODE_FUNC_IMPLEMENT
   } destroy;
 };
-
-
-extern HB_INTERNAL const hb_unicode_funcs_t _hb_unicode_funcs_nil;
+DECLARE_NULL_INSTANCE (hb_unicode_funcs_t);
 
 
 /* Modified combining marks */

src/hb-unicode.cc

@@ -185,7 +185,8 @@ hb_unicode_funcs_create (hb_unicode_funcs_t *parent)
 }
 
 
-const hb_unicode_funcs_t _hb_unicode_funcs_nil = {
+DEFINE_NULL_INSTANCE (hb_unicode_funcs_t) =
+{
   HB_OBJECT_HEADER_STATIC,
 
   nullptr, /* parent */
@@ -209,7 +210,7 @@ const hb_unicode_funcs_t _hb_unicode_funcs_nil = {
 hb_unicode_funcs_t *
 hb_unicode_funcs_get_empty (void)
 {
-  return const_cast<hb_unicode_funcs_t *> (&_hb_unicode_funcs_nil);
+  return const_cast<hb_unicode_funcs_t *> (&Null(hb_unicode_funcs_t));
 }
 
 /**