[OT] Start adding Lookup-level serialize API

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

@@ -313,11 +313,29 @@ struct Lookup
     return flag;
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+			 unsigned int lookup_type,
+			 uint32_t lookup_props,
+			 unsigned int num_subtables)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    lookupType.set (lookup_type);
+    lookupFlag.set (lookup_props & 0xFFFF);
+    if (unlikely (!subTable.serialize (c, num_subtables))) return TRACE_RETURN (false);
+    if ((lookup_props >> 16) || lookupFlag & LookupFlag::UseMarkFilteringSet)
+    {
+      USHORT &markFilteringSet = StructAfter<USHORT> (subTable);
+      markFilteringSet.set (lookup_props >> 16);
+    }
+    return TRACE_RETURN (true);
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     /* Real sanitize of the subtables is done by GSUB/GPOS/... */
     if (!(c->check_struct (this) && subTable.sanitize (c))) return TRACE_RETURN (false);
-    if (unlikely (lookupFlag & LookupFlag::UseMarkFilteringSet))
+    if (lookupFlag & LookupFlag::UseMarkFilteringSet)
     {
       USHORT &markFilteringSet = StructAfter<USHORT> (subTable);
       if (!markFilteringSet.sanitize (c)) return TRACE_RETURN (false);