boost之is_pointer

//BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_pointer,T,::boost::detail::is_pointer_impl<T>::value)
//1.
template< typename T > struct is_pointer
: public ::boost::integral_constant<bool,::boost::detail::is_pointer_impl<T>::value>
{
public:
};

is_pointer<T>::value == ::boost::detail::is_pointer_impl<T>::value
template< typename T >
struct is_pointer_impl
{
BOOST_STATIC_CONSTANT(bool, value =
(::boost::type_traits::ice_and<
::boost::detail::is_pointer_helper<typename remove_cv<T>::type>::value
, ::boost::type_traits::ice_not<
::boost::is_member_pointer<T>::value
>::value
>::value)
);
};

------------------------------------------------
template< typename T > struct is_pointer_helper
{
BOOST_STATIC_CONSTANT(bool, value = false);
};
TT_AUX_BOOL_TRAIT_HELPER_PARTIAL_SPEC(is_pointer_helper,T*,true)
展开为
template< typename T > struct is_pointer_helper<T*>
{
BOOST_STATIC_CONSTANT(bool, value = true);
};
------------------------------------------------
template <bool b>
struct ice_not
{
BOOST_STATIC_CONSTANT(bool, value = true);
};

template <>
struct ice_not<true>
{
BOOST_STATIC_CONSTANT(bool, value = false);
};
-------------------------------------------------
template <bool b1, bool b2, bool b3 = true, bool b4 = true, bool b5 = true, bool b6 = true, bool b7 = true>
struct ice_and;

template <bool b1, bool b2, bool b3, bool b4, bool b5, bool b6, bool b7>
struct ice_and
{
BOOST_STATIC_CONSTANT(bool, value = false);
};

template <>
struct ice_and<true, true, true, true, true, true, true>
{
BOOST_STATIC_CONSTANT(bool, value = true);
};