Re: [Spirit-general] rule of thumb for performance of boost::variant?

[Joel R. <jo...@gm...>]

>


I started with this OCaml recursive type:

type ty =
   | TyAny
   | TyInt
   | TyFloat
   | TyBool
   | TyStr
   | TyColor
   | TyStyle
   | TyList of ty
   | TyArray of ty
   | TySeries of ty
   | TyInput of ty
   | TyRef of ty
   | TyUnit
   | TyPrintDest
   | TyPrintExpr

and ended up with this MUCH larger of C++

     struct AnyType {};
     struct IntType {};
     struct FloatType {};
     struct BoolType {};
     struct StrType {};
     struct ColorType {};
     struct StyleType {};
     struct UnitType {};
     struct PrintDestType {};
     struct PrintExprType {};

     struct ListType;
     struct ArrayType;
     struct SeriesType;
     struct InputType;
     struct RefType;

     struct TypeAST
     {
         typedef
             boost::variant<
                   nil
                 , boost::recursive_wrapper<TypeAST>
                 , boost::recursive_wrapper<ListType>
                 , boost::recursive_wrapper<ArrayType>
                 , boost::recursive_wrapper<SeriesType>
                 , boost::recursive_wrapper<InputType>
                 , boost::recursive_wrapper<RefType>
                 , AnyType
                 , IntType
                 , FloatType
                 , BoolType
                 , StrType
                 , ColorType
                 , StyleType
                 , UnitType
                 , PrintDestType
                 , PrintExprType
             >
         type;

         TypeAST()
           : ty(nil()) {}

         template <typename T>
         TypeAST(T const& ty)
           : ty(ty) {}

         type ty;
     };

     struct TypeOf
     {
         TypeOf(
             TypeAST const& ty
         ): ty(ty) {}

         TypeAST ty;
     };

     struct ListType: public TypeOf {};
     struct ArrayType: public TypeOf {};
     struct SeriesType: public TypeOf {};
     struct InputType: public TypeOf {};
     struct RefType: public TypeOf {};

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