// Copyright 2000 John Maddock (john@johnmaddock.co.uk)

// Copyright 2000 Jeremy Siek (jsiek@lsc.nd.edu)

// Copyright 1999, 2000 Jaakko J„rvi (jaakko.jarvi@cs.utu.fi)

//

//  Use, modification and distribution are subject to the Boost Software License,

//  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at

//  http://www.boost.org/LICENSE_1_0.txt).

//

//  See http://www.boost.org/libs/type_traits for most recent version including documentation.

#ifndef BOOST_TT_IS_CONVERTIBLE_HPP_INCLUDED

#define BOOST_TT_IS_CONVERTIBLE_HPP_INCLUDED

#include <boost/type_traits/detail/yes_no_type.hpp>

#include <boost/type_traits/config.hpp>

#include <boost/type_traits/is_array.hpp>

#include <boost/type_traits/add_reference.hpp>

#include <boost/type_traits/ice.hpp>

#include <boost/type_traits/is_arithmetic.hpp>

#include <boost/type_traits/is_void.hpp>

#ifndef BOOST_NO_IS_ABSTRACT

#include <boost/type_traits/is_abstract.hpp>

#endif

#if defined(__MWERKS__)

#include <boost/type_traits/is_function.hpp>

#include <boost/type_traits/remove_reference.hpp>

#endif

// should be always the last #include directive

#include <boost/type_traits/detail/bool_trait_def.hpp>

namespace boost {

// is one type convertable to another?

//

// there are multiple versions of the is_convertible

// template, almost every compiler seems to require its

// own version.

//

// Thanks to Andrei Alexandrescu for the original version of the

// conversion detection technique!

//

namespace detail {

// MS specific version:

#if defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)

// This workaround is necessary to handle when From is void

// which is normally taken care of by the partial specialization

// of the is_convertible typename.

using ::boost::type_traits::yes_type;

using ::boost::type_traits::no_type;

template< typename From >

struct does_conversion_exist

{

    template< typename To > struct result_

    {

        static no_type BOOST_TT_DECL _m_check(...);

        static yes_type BOOST_TT_DECL _m_check(To);

        static From _m_from;

        enum { value = sizeof( _m_check(_m_from) ) == sizeof(yes_type) };

    };

};

template<>

struct does_conversion_exist<void>

{

    template< typename To > struct result_

    {

        enum { value = ::boost::is_void<To>::value };

    };

};

template <typename From, typename To>

struct is_convertible_basic_impl

    : does_conversion_exist<From>::template result_<To>

{

};

#elif defined(__BORLANDC__) && (__BORLANDC__ < 0x560)

//

// special version for Borland compilers

// this version breaks when used for some

// UDT conversions:

//

template <typename From, typename To>

struct is_convertible_impl

{

#pragma option push -w-8074

    // This workaround for Borland breaks the EDG C++ frontend,

    // so we only use it for Borland.

    template <typename T> struct checker

    {

        static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(...);

        static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(T);

    };

    static From _m_from;

    static bool const value = sizeof( checker<To>::_m_check(_m_from) )

        == sizeof(::boost::type_traits::yes_type);

#pragma option pop

};

#elif defined(__GNUC__) || defined(__BORLANDC__) && (__BORLANDC__ < 0x600)

// special version for gcc compiler + recent Borland versions

// note that this does not pass UDT's through (...)

struct any_conversion

{

    template <typename T> any_conversion(const volatile T&);

    template <typename T> any_conversion(T&);

};

template <typename T> struct checker

{

    static boost::type_traits::no_type _m_check(any_conversion ...);

    static boost::type_traits::yes_type _m_check(T, int);

};

template <typename From, typename To>

struct is_convertible_basic_impl

{

    static From _m_from;

    static bool const value = sizeof( detail::checker<To>::_m_check(_m_from, 0) )

        == sizeof(::boost::type_traits::yes_type);

};

#elif (defined(__EDG_VERSION__) && (__EDG_VERSION__ >= 245) && !defined(__ICL)) \

      || defined(__IBMCPP__) || defined(__HP_aCC)

//

// This is *almost* an ideal world implementation as it doesn't rely

// on undefined behaviour by passing UDT's through (...).

// Unfortunately it doesn't quite pass all the tests for most compilers (sigh...)

// Enable this for your compiler if is_convertible_test.cpp will compile it...

//

// Note we do not enable this for VC7.1, because even though it passes all the

// type_traits tests it is known to cause problems when instantiation occurs

// deep within the instantiation tree :-(

//

struct any_conversion

{

    template <typename T> any_conversion(const volatile T&);

    // we need this constructor to catch references to functions

    // (which can not be cv-qualified):

    template <typename T> any_conversion(T&);

};

template <typename From, typename To>

struct is_convertible_basic_impl

{

    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(any_conversion ...);

    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To, int);

       static From _m_from;

    BOOST_STATIC_CONSTANT(bool, value =

        sizeof( _m_check(_m_from, 0) ) == sizeof(::boost::type_traits::yes_type)

        );

};

#elif defined(__DMC__)

struct any_conversion

{

    template <typename T> any_conversion(const volatile T&);

    // we need this constructor to catch references to functions

    // (which can not be cv-qualified):

    template <typename T> any_conversion(T&);

};

template <typename From, typename To>

struct is_convertible_basic_impl

{

    // Using '...' doesn't always work on Digital Mars. This version seems to.

    template <class T>

    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(any_conversion,  float, T);

    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To, int, int);

    static From _m_from;

    // Static constants sometime cause the conversion of _m_from to To to be

    // called. This doesn't happen with an enum.

    enum { value =

        sizeof( _m_check(_m_from, 0, 0) ) == sizeof(::boost::type_traits::yes_type)

        };

};

#elif defined(__MWERKS__)

// 

// CW works with the technique implemented above for EDG, except when From

// is a function type (or a reference to such a type), in which case

// any_conversion won't be accepted as a valid conversion. We detect this

// exceptional situation and channel it through an alternative algorithm.

//

template <typename From, typename To,bool FromIsFunctionRef>

struct is_convertible_basic_impl_aux;

struct any_conversion

{

    template <typename T> any_conversion(const volatile T&);

};

template <typename From, typename To>

struct is_convertible_basic_impl_aux<From,To,false /*FromIsFunctionRef*/>

{

    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(any_conversion ...);

    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To, int);

    static From _m_from;

    BOOST_STATIC_CONSTANT(bool, value =

        sizeof( _m_check(_m_from, 0) ) == sizeof(::boost::type_traits::yes_type)

        );

};

template <typename From, typename To>

struct is_convertible_basic_impl_aux<From,To,true /*FromIsFunctionRef*/>

{

    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(...);

    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To);

    static From _m_from;

    BOOST_STATIC_CONSTANT(bool, value =

        sizeof( _m_check(_m_from) ) == sizeof(::boost::type_traits::yes_type)

        );

};

template <typename From, typename To>

struct is_convertible_basic_impl:

  is_convertible_basic_impl_aux<

    From,To,

    ::boost::is_function<typename ::boost::remove_reference<From>::type>::value

  >

{};

#else

//

// This version seems to work pretty well for a wide spectrum of compilers,

// however it does rely on undefined behaviour by passing UDT's through (...).

//

template <typename From, typename To>

struct is_convertible_basic_impl

{

    static ::boost::type_traits::no_type BOOST_TT_DECL _m_check(...);

    static ::boost::type_traits::yes_type BOOST_TT_DECL _m_check(To);

    static From _m_from;

#ifdef BOOST_MSVC

#pragma warning(push)

#pragma warning(disable:4244)

#endif

    BOOST_STATIC_CONSTANT(bool, value =

        sizeof( _m_check(_m_from) ) == sizeof(::boost::type_traits::yes_type)

        );

#ifdef BOOST_MSVC

#pragma warning(pop)

#endif

};

#endif // is_convertible_impl

#if defined(__DMC__)

// As before, a static constant sometimes causes errors on Digital Mars.

template <typename From, typename To>

struct is_convertible_impl

{

    typedef typename add_reference<From>::type ref_type;

    enum { value =

        (::boost::type_traits::ice_and<

            ::boost::type_traits::ice_or<

               ::boost::detail::is_convertible_basic_impl<ref_type,To>::value,

               ::boost::is_void<To>::value

            >::value,

            ::boost::type_traits::ice_not<

               ::boost::is_array<To>::value

            >::value

        >::value) };

};

#elif !defined(__BORLANDC__) || __BORLANDC__ > 0x551

template <typename From, typename To>

struct is_convertible_impl

{

    typedef typename add_reference<From>::type ref_type;

    BOOST_STATIC_CONSTANT(bool, value =

        (::boost::type_traits::ice_and<

            ::boost::type_traits::ice_or<

               ::boost::detail::is_convertible_basic_impl<ref_type,To>::value,

               ::boost::is_void<To>::value

            >::value,

            ::boost::type_traits::ice_not<

               ::boost::is_array<To>::value

            >::value

        >::value)

        );

};

#endif

template <bool trivial1, bool trivial2, bool abstract_target>

struct is_convertible_impl_select

{

   template <class From, class To>

   struct rebind

   {

      typedef is_convertible_impl<From, To> type;

   };

};

template <>

struct is_convertible_impl_select<true, true, false>

{

   template <class From, class To>

   struct rebind

   {

      typedef true_type type;

   };

};

template <>

struct is_convertible_impl_select<false, false, true>

{

   template <class From, class To>

   struct rebind

   {

      typedef false_type type;

   };

};

template <>

struct is_convertible_impl_select<true, false, true>

{

   template <class From, class To>

   struct rebind

   {

      typedef false_type type;

   };

};

template <typename From, typename To>

struct is_convertible_impl_dispatch_base

{

#if !BOOST_WORKAROUND(__HP_aCC, < 60700)

   typedef is_convertible_impl_select< 

      ::boost::is_arithmetic<From>::value, 

      ::boost::is_arithmetic<To>::value,

#ifndef BOOST_NO_IS_ABSTRACT

      ::boost::is_abstract<To>::value

#else

      false

#endif

   > selector;

#else

   typedef is_convertible_impl_select<false, false, false> selector;

#endif

   typedef typename selector::template rebind<From, To> isc_binder;

   typedef typename isc_binder::type type;

};

template <typename From, typename To>

struct is_convertible_impl_dispatch 

   : public is_convertible_impl_dispatch_base<From, To>::type

{};

//

// Now add the full and partial specialisations

// for void types, these are common to all the

// implementation above:

//

#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS

#   define TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1,spec2,value) \

    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2,value) \

    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2 const,value) \

    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2 volatile,value) \

    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(trait,spec1,spec2 const volatile,value) \

    /**/

#   define TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2(trait,spec1,spec2,value) \

    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1,spec2,value) \

    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1 const,spec2,value) \

    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1 volatile,spec2,value) \

    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1(trait,spec1 const volatile,spec2,value) \

    /**/

    TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2(is_convertible,void,void,true)

#   undef TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2

#   undef TT_AUX_BOOL_CV_VOID_TRAIT_SPEC2_PART1

#else

    BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC2(is_convertible,void,void,true)

#endif // BOOST_NO_CV_VOID_SPECIALIZATIONS

#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void,To,false)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void,true)

#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void const,To,false)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void volatile,To,false)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename To,is_convertible,void const volatile,To,false)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void const,true)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void volatile,true)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_PARTIAL_SPEC2_1(typename From,is_convertible,From,void const volatile,true)

#endif

#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

} // namespace detail

BOOST_TT_AUX_BOOL_TRAIT_DEF2(is_convertible,From,To,(::boost::detail::is_convertible_impl_dispatch<From,To>::value))

} // namespace boost

#include <boost/type_traits/detail/bool_trait_undef.hpp>

#endif // BOOST_TT_IS_CONVERTIBLE_HPP_INCLUDED