generic-library/cxx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

I believe tuple is still under development in the standard. Daniel Krugler is/will be making convincing arguments that a modified form of LWG 2051 (currently NAD Future) is easily acheivable and desirable. He has demonstrated that a tuple<T...> where all of the T are implicitly convertible from U... should have a tuple constructor that is also implicit, instead of explicit. This would support the use cases in LWG 2051 while not undermining T... with explicit conversions from U.... This check-in is an experimental implementation of Daniel's work. I believe this work to be mature enough to warrant inclusion into libc++. If anyone sees real-world problems that this check in causes, please let me know and I will revert it, and provide the feedback to the LWG.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@153855 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Howard Hinnant
2012-04-01 23:10:42 +00:00
parent 9aa4e11451
commit dc1345fd44
4 changed files with 105 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
include/__tuple
View File

@@ -216,7 +216,7 @@ struct __tuple_convertible_imp : public false_type {};
template <class _Tp0, class ..._Tp, class _Up0, class ..._Up>
struct __tuple_convertible_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> >
: public integral_constant<bool,
is_constructible<_Up0, _Tp0>::value &&
is_convertible<_Tp0, _Up0>::value &&
__tuple_convertible_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {};
template <>
@@ -235,6 +235,33 @@ struct __tuple_convertible<_Tp, _Up, true, true>
typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type>
{};
// __tuple_constructible
template <bool, class _Tp, class _Up>
struct __tuple_constructible_imp : public false_type {};
template <class _Tp0, class ..._Tp, class _Up0, class ..._Up>
struct __tuple_constructible_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...> >
: public integral_constant<bool,
is_constructible<_Up0, _Tp0>::value &&
__tuple_constructible_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...> >::value> {};
template <>
struct __tuple_constructible_imp<true, __tuple_types<>, __tuple_types<> >
: public true_type {};
template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
bool = __tuple_like<_Up>::value>
struct __tuple_constructible
: public false_type {};
template <class _Tp, class _Up>
struct __tuple_constructible<_Tp, _Up, true, true>
: public __tuple_constructible_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
tuple_size<_Up>::value,
typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type>
{};
// __tuple_assignable
template <bool, class _Tp, class _Up>