Reply to problem mit template klasse als template parameter on Sat, 12 Nov 2005 09:35:04 GMT

camper — Sat, 12 Nov 2005 09:35:04 GMT

//! \brief  Helper template to remove __w64 qualifier from a type
    template struct RemoveWarning64 { typedef T type; };
    template<> struct RemoveWarning64< int >
    {
        typedef int type;
    };
    template<> struct RemoveWarning64< const int >
    {
        typedef const int type;
    };
    template<> struct RemoveWarning64< volatile int >
    {
        typedef volatile int type;
    };
    template<> struct RemoveWarning64< const volatile int >
    {
        typedef const volatile int type;
    };
    template<> struct RemoveWarning64< long >
    {
        typedef long type;
    };
    template<> struct RemoveWarning64< const long >
    {
        typedef const long type;
    };
    template<> struct RemoveWarning64< volatile long >
    {
        typedef volatile long type;
    };
    template<> struct RemoveWarning64< const volatile long >
    {
        typedef const volatile long type;
    };
    template struct RemoveWarning64< T* >
    {
        typedef typename boost::add_pointer< T >::type type;
    };
    template struct RemoveWarning64< T* const >
    {
        typedef const typename boost::add_pointer< T >::type type;
    };
    template struct RemoveWarning64< T* volatile >
    {
        typedef volatile typename boost::add_pointer< T >::type type;
    };
    template struct RemoveWarning64< T* const volatile >
    {
        typedef const volatile typename boost::add_pointer< T >::type type;
    };
    //! \brief  Helper template which applies all cv qualifiers of two given
    //!         types to the first type.
    template
    struct UniteCvQualifiers
    {
        typedef typename boost::mpl::apply_wrap4< boost::mpl::arg< 
            boost::is_volatile< U >::value
                ? boost::is_const< U >::value
                    ? 4
                    : 3
                : boost::is_const< U >::value
                    ? 2
                    : 1
            >,
            typename RemoveWarning64< T >::type,
            typename RemoveWarning64< const T >::type,
            typename RemoveWarning64< volatile T >::type,
            typename RemoveWarning64< const volatile T >::type >::type type;
    };

    struct NoType {};
    struct YesType { NoType dummy_[ 2 ]; };
    //! Helper template to determine the type of given expression
    template
    struct Z
    {
        static YesType isLeftType(const X&);
        static NoType isLeftType(const Y&);
    };
    template
    struct Z< X, X >
    {
        static YesType isLeftType(const X&);
    };
    template
    struct MinMaxResult
    {
    public:
        typedef typename RemoveWarning64< typename boost::remove_cv< T >::type >::type T_;
        typedef typename RemoveWarning64< typename boost::remove_cv< U >::type >::type U_;
        static T_ createT_();
        static U_ createU_();
    public:
        typedef typename boost::mpl::apply_wrap4<
            boost::mpl::arg<
                boost::is_same< T_, U_ >::value
                    ? boost::is_volatile< T >::value || boost::is_volatile< U >::value
                        ? 1
                        : 4
                    : boost::is_integral< T_ >::value && boost::is_integral< U_ >::value
                        ? boost::is_same< T_, char >::value || boost::is_same< U_, char >::value
                            ? 1
                            : std::numeric_limits< T_ >::is_signed == std::numeric_limits< U_ >::is_signed
                                ? sizeof( typename Z< T_, U_ >::isLeftType( true ? createT_() : createU_() ) )
                                                                                        == sizeof( YesType )
                                    ? 2
                                    : 3
                                : 1
                        : boost::is_float< T_ >::value && boost::is_float< U_ >::value
                            ? sizeof( typename Z< T_, U_ >::isLeftType( true ? createT_() : createU_() ) )
                                                                                        == sizeof( YesType )
                                ? 2
                                : 3
                            : boost::is_pointer< T_ >::value && boost::is_pointer< U_ >::value
                                ? boost::is_base_and_derived< typename boost::remove_pointer< T_ >::type,
                                                              typename boost::remove_pointer< U_ >::type >::value
                                    ? 2
                                    : boost::is_base_and_derived< typename boost::remove_pointer< U_ >::type,
                                                                  typename boost::remove_pointer< T_ >::type >::value
                                          ? 3
                                          : 1
                                : 1
            >,
            NoType, T_, U_, typename RemoveWarning64< typename UniteCvQualifiers< T, U >::type >::type
        >::type type; // <===============================
    };

da bekomme ich in der markierten zeile:
error C3203: 'arg' : class template invalid as template argument for template parameter 'F', expected a real type

ist bestimmt was simples, aber irgendwie entgeht es mir, schiesslich ist arg< ... > eine klasse und kein template

irgendwelche ideen dazu sind willkommen. bestimmt kann man das ganze auch generell viel einfcher bauen, inspiriert ist das ganze von
http://erdani.org/publications/cuj-04-2001.html
allerdings wollte ich kein loki benutzen und auch einige unsichere kombinationen (z.B. unsigned und signed typen) ausschliessen.

Reply to problem mit template klasse als template parameter on Sat, 12 Nov 2005 09:57:55 GMT

CStoll — Sat, 12 Nov 2005 09:57:55 GMT

Args, das sieht aber übersichtlich aus

typedef typename boost::mpl::apply_wrap4<
  boost::mpl::arg<
    ...
  >,//<--
  NoType,
  T_,
  U_,
  RemoveWarning64< UniteCvQualifiers< T, U >::type >::type
>::type type;

Kann es sein, daß du das arg<...>::type vergessen hast?

Reply to problem mit template klasse als template parameter on Sat, 12 Nov 2005 10:03:37 GMT

camper — Sat, 12 Nov 2005 10:03:37 GMT

das müsste so richtig sein:
http://www.boost.org/libs/mpl/doc/refmanual/arg.html
es funktioniert in RemoveWarning64 ja auch

ich versuch mich gerade etwas in mpl hereinzufinden, bestimmt geht das ganze auch eleganter.