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Unordered: Another attempt at member detection.

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Another stab in the dark. Doing SFINAE in the return type appears to
work well, apart for Visual C++ 8.0. Will have to see how the test
results go for some compilers.

[SVN r74173]
This commit is contained in:
Daniel James
2011-08-30 22:02:27 +00:00
parent ceef4d6521
commit 659b6fe8ba
1 changed files with 31 additions and 15 deletions
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46
include/boost/unordered/detail/allocator_helpers.hpp
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@ -97,20 +97,7 @@ namespace boost { namespace unordered { namespace detail {
struct choice1 : choice2 { typedef char (&type)[1]; };
choice1 choose();
#if !defined(__IBMCPP__)
#define BOOST_UNORDERED_MEMBER_CHECK(tname) BOOST_DEDUCED_TYPENAME X::tname*
#else
template <typename T> struct wrap { typedef void* type; };
#define BOOST_UNORDERED_MEMBER_CHECK(tname) \
BOOST_DEDUCED_TYPENAME wrap< \
BOOST_DEDUCED_TYPENAME X::tname \
>::type
#endif
#if defined(BOOST_MSVC) && BOOST_MSVC <= 1400
#define BOOST_UNORDERED_DEFAULT_TYPE_TMPLT(tname) \
template <typename Tp, typename Default> \
@ -118,7 +105,7 @@ namespace boost { namespace unordered { namespace detail {
\
template <typename X> \
static choice1::type test(choice1, \
BOOST_UNORDERED_MEMBER_CHECK(tname) = 0); \
BOOST_DEDUCED_TYPENAME X::tname* = 0); \
\
template <typename X> \
static choice2::type test(choice2, void* = 0); \
@ -133,6 +120,35 @@ namespace boost { namespace unordered { namespace detail {
::type::tname type; \
}
#else
template <typename T, typename T2>
struct sfinae : T2 {};
#define BOOST_UNORDERED_DEFAULT_TYPE_TMPLT(tname) \
template <typename Tp, typename Default> \
struct default_type_ ## tname { \
\
template <typename X> \
static BOOST_DEDUCED_TYPENAME sfinae< \
BOOST_DEDUCED_TYPENAME X::tname, choice1>::type \
test(choice1); \
\
template <typename X> \
static choice2::type test(choice2); \
\
struct DefaultWrap { typedef Default tname; }; \
\
enum { value = (1 == sizeof(test<Tp>(choose()))) }; \
\
typedef BOOST_DEDUCED_TYPENAME \
boost::detail::if_true<value>:: \
BOOST_NESTED_TEMPLATE then<Tp, DefaultWrap> \
::type::tname type; \
}
#endif
#define BOOST_UNORDERED_DEFAULT_TYPE(T,tname, arg) \
BOOST_DEDUCED_TYPENAME default_type_ ## tname<T, arg>::type