Make Extension a template

src/hb-ot-layout-gpos-table.hh

@@ -1246,7 +1246,7 @@ struct ContextPos : Context {};
 
 struct ChainContextPos : ChainContext {};
 
-struct ExtensionPos : Extension
+struct ExtensionPos : Extension<ExtensionPos>
 {
   inline const struct PosLookupSubTable& get_subtable (void) const
   {
@@ -1255,9 +1255,6 @@ struct ExtensionPos : Extension
     return StructAtOffset<PosLookupSubTable> (this, offset);
   }
 
-  template <typename context_t>
-  inline typename context_t::return_t process (context_t *c) const;
-
   inline bool sanitize (hb_sanitize_context_t *c);
 };
 
@@ -1525,12 +1522,6 @@ GPOS::position_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer, hb_bool_t
 
 /* Out-of-class implementation for methods recursing */
 
-template <typename context_t>
-inline typename context_t::return_t ExtensionPos::process (context_t *c) const
-{
-  return get_subtable ().process (c, get_type ());
-}
-
 inline bool ExtensionPos::sanitize (hb_sanitize_context_t *c)
 {
   TRACE_SANITIZE (this);

src/hb-ot-layout-gsub-table.hh

@@ -878,7 +878,7 @@ struct ContextSubst : Context {};
 
 struct ChainContextSubst : ChainContext {};
 
-struct ExtensionSubst : Extension
+struct ExtensionSubst : Extension<ExtensionSubst>
 {
   inline const struct SubstLookupSubTable& get_subtable (void) const
   {
@@ -887,9 +887,6 @@ struct ExtensionSubst : Extension
     return StructAtOffset<SubstLookupSubTable> (this, offset);
   }
 
-  template <typename context_t>
-  inline typename context_t::return_t process (context_t *c) const;
-
   inline bool sanitize (hb_sanitize_context_t *c);
 
   inline bool is_reverse (void) const;
@@ -1380,12 +1377,6 @@ GSUB::substitute_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer HB_UNUSE
 
 /* Out-of-class implementation for methods recursing */
 
-template <typename context_t>
-inline typename context_t::return_t ExtensionSubst::process (context_t *c) const
-{
-  return get_subtable ().process (c, get_type ());
-}
-
 inline bool ExtensionSubst::sanitize (hb_sanitize_context_t *c)
 {
   TRACE_SANITIZE (this);

src/hb-ot-layout-gsubgpos-private.hh

@@ -1765,6 +1765,7 @@ struct ExtensionFormat1
   DEFINE_SIZE_STATIC (8);
 };
 
+template <typename T>
 struct Extension
 {
   inline unsigned int get_type (void) const
@@ -1782,6 +1783,12 @@ struct Extension
     }
   }
 
+  template <typename context_t>
+  inline typename context_t::return_t process (context_t *c) const
+  {
+    return CastP<T>(this)->get_subtable ().process (c, get_type ());
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE (this);
     if (!u.format.sanitize (c)) return TRACE_RETURN (false);