[layout] Refactor get_subtable()

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

@@ -571,6 +571,17 @@ struct Lookup
 {
   inline unsigned int get_subtable_count (void) const { return subTable.len; }
 
+  template <typename SubTableType>
+  inline const SubTableType& get_subtable (unsigned int i) const
+  { return this+CastR<OffsetArrayOf<SubTableType> > (subTable)[i]; }
+
+  template <typename SubTableType>
+  inline const OffsetArrayOf<SubTableType>& get_subtables (void) const
+  { return CastR<OffsetArrayOf<SubTableType> > (subTable); }
+  template <typename SubTableType>
+  inline OffsetArrayOf<SubTableType>& get_subtables (void)
+  { return CastR<OffsetArrayOf<SubTableType> > (subTable); }
+
   inline unsigned int get_type (void) const { return lookupType; }
 
   /* lookup_props is a 32-bit integer where the lower 16-bit is LookupFlag and
@@ -618,6 +629,7 @@ struct Lookup
     return TRACE_RETURN (true);
   }
 
+  private:
   USHORT	lookupType;		/* Different enumerations for GSUB and GPOS */
   USHORT	lookupFlag;		/* Lookup qualifiers */
   ArrayOf<Offset<> >

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

@@ -1489,7 +1489,7 @@ struct PosLookupSubTable
 struct PosLookup : Lookup
 {
   inline const PosLookupSubTable& get_subtable (unsigned int i) const
-  { return this+CastR<OffsetArrayOf<PosLookupSubTable> > (subTable)[i]; }
+  { return Lookup::get_subtable<PosLookupSubTable> (i); }
 
   inline bool is_reverse (void) const
   {
@@ -1540,7 +1540,7 @@ struct PosLookup : Lookup
   {
     TRACE_SANITIZE (this);
     if (unlikely (!Lookup::sanitize (c))) return TRACE_RETURN (false);
-    const OffsetArrayOf<PosLookupSubTable> &list = CastR<OffsetArrayOf<PosLookupSubTable> > (subTable);
+    const OffsetArrayOf<PosLookupSubTable> &list = get_subtables<PosLookupSubTable> ();
     return TRACE_RETURN (list.sanitize (c, this, get_type ()));
   }
 };

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

@@ -1170,7 +1170,7 @@ struct SubstLookupSubTable
 struct SubstLookup : Lookup
 {
   inline const SubstLookupSubTable& get_subtable (unsigned int i) const
-  { return this+CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable)[i]; }
+  { return Lookup::get_subtable<SubstLookupSubTable> (i); }
 
   inline static bool lookup_type_is_reverse (unsigned int lookup_type)
   { return lookup_type == SubstLookupSubTable::ReverseChainSingle; }
@@ -1225,7 +1225,7 @@ struct SubstLookup : Lookup
 
   inline SubstLookupSubTable& serialize_subtable (hb_serialize_context_t *c,
 						  unsigned int i)
-  { return CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable)[i].serialize (c, this); }
+  { return get_subtables<SubstLookupSubTable> ()[i].serialize (c, this); }
 
   inline bool serialize_single (hb_serialize_context_t *c,
 				uint32_t lookup_props,
@@ -1300,7 +1300,7 @@ struct SubstLookup : Lookup
   {
     TRACE_SANITIZE (this);
     if (unlikely (!Lookup::sanitize (c))) return TRACE_RETURN (false);
-    const OffsetArrayOf<SubstLookupSubTable> &list = CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable);
+    const OffsetArrayOf<SubstLookupSubTable> &list = get_subtables<SubstLookupSubTable> ();
     if (unlikely (!list.sanitize (c, this, get_type ()))) return TRACE_RETURN (false);
 
     if (unlikely (get_type () == SubstLookupSubTable::Extension))