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SFINAE enabled result_of fixes [7343]

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[SVN r80605]
This commit is contained in:
Daniel Walker 2012-09-19 23:10:08 +00:00
parent b6a55f878c
commit ac9f617f7f
3 changed files with 107 additions and 3 deletions
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66
include/boost/utility/detail/result_of_iterate.hpp
View File

@ -58,17 +58,79 @@ struct result_of<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
namespace detail {
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1700))
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct cpp0x_result_of_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
class is_callable<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))> {
typedef char (&pass)[1];
typedef char (&fail)[2];
template<typename G BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename S)>
struct sub {};
template<typename S>
struct stub {};
template<typename G BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename S)>
static pass test(sub<G BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),S)>
, stub<
decltype(
boost::declval<G>()(
BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), boost::declval<S, >() BOOST_PP_INTERCEPT)
)
)
>* x = 0);
static fail test(...);
public:
const static bool value = sizeof(pass) == sizeof(test(sub<F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)
>()));
typedef typename boost::mpl::bool_<value>::type type;
};
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct cpp0x_result_of_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), true>
: lazy_enable_if<
is_callable<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
, cpp0x_result_of_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), false>
>
{};
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct cpp0x_result_of_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), false>
{
typedef decltype(
boost::declval<F>()(
BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), declval<T, >() BOOST_PP_INTERCEPT)
BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), boost::declval<T, >() BOOST_PP_INTERCEPT)
)
) type;
};
#else // BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1700))
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct cpp0x_result_of_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)),
typename result_of_always_void<decltype(
boost::declval<F>()(
BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), boost::declval<T, >() BOOST_PP_INTERCEPT)
)
)>::type> {
typedef decltype(
boost::declval<F>()(
BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), boost::declval<T, >() BOOST_PP_INTERCEPT)
)
) type;
};
#endif // BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1700))
} // namespace detail
#else // defined(BOOST_RESULT_OF_USE_DECLTYPE)

18
include/boost/utility/result_of.hpp
View File

@ -25,6 +25,7 @@
#include <boost/type_traits/is_member_function_pointer.hpp>
#include <boost/type_traits/remove_cv.hpp>
#include <boost/utility/declval.hpp>
#include <boost/utility/enable_if.hpp>
#ifndef BOOST_RESULT_OF_NUM_ARGS
# define BOOST_RESULT_OF_NUM_ARGS 16
@ -59,7 +60,22 @@ namespace detail {
BOOST_MPL_HAS_XXX_TRAIT_DEF(result_type)
template<typename F, typename FArgs, bool HasResultType> struct tr1_result_of_impl;
template<typename F> struct cpp0x_result_of_impl;
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1700))
template<typename F> class is_callable;
template<typename F, bool TestCallability = true> struct cpp0x_result_of_impl;
#else // BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1700))
template<typename T>
struct result_of_always_void
{
typedef void type;
};
template<typename F, typename Enable = void> struct cpp0x_result_of_impl {};
#endif // BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1700))
template<typename F>
struct result_of_void_impl

26
test/result_of_test.cpp
View File

@ -129,6 +129,27 @@ struct no_result_type_or_result_template
#endif
};
// sfinae_tests are derived from example code from Joel de Guzman,
// which demonstrated the interaction between result_of and SFINAE.
template <typename F, typename Arg>
typename boost::result_of<F(Arg const&)>::type
sfinae_test(F f, Arg const& arg)
{
return f(arg);
}
template <typename F, typename Arg>
typename boost::result_of<F(Arg&)>::type
sfinae_test(F f, Arg& arg)
{
return f(arg);
}
int sfinae_test_f(int& i)
{
return i;
}
struct X {};
int main()
@ -268,5 +289,10 @@ int main()
#endif
#endif
#if defined(BOOST_RESULT_OF_USE_DECLTYPE)
int i = 123;
sfinae_test(sfinae_test_f, i);
#endif // defined(BOOST_RESULT_OF_USE_DECLTYPE)
return 0;
}