Brought call_once variadic call up to current spec, which allows move-only functors and move-only arguments, but disallows functors with non-const lvalue reference parameters.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@131414 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Howard Hinnant 2011-05-16 19:05:11 +00:00
parent 656bdc3667
commit ad935d583d
2 changed files with 61 additions and 4 deletions

View File

@ -175,6 +175,9 @@ template<class Callable, class ...Args>
#include <__config>
#include <__mutex_base>
#include <functional>
#ifndef _LIBCPP_HAS_NO_VARIADICS
#include <tuple>
#endif
#pragma GCC system_header
@ -455,6 +458,39 @@ private:
#endif // _LIBCPP_HAS_NO_VARIADICS
};
#ifndef _LIBCPP_HAS_NO_VARIADICS
template <class _F>
class __call_once_param
{
_F __f_;
public:
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
_LIBCPP_INLINE_VISIBILITY
explicit __call_once_param(_F&& __f) : __f_(_STD::move(__f)) {}
#else
_LIBCPP_INLINE_VISIBILITY
explicit __call_once_param(const _F& __f) : __f_(__f) {}
#endif
_LIBCPP_INLINE_VISIBILITY
void operator()()
{
typedef typename __make_tuple_indices<tuple_size<_F>::value, 1>::type _Index;
__execute(_Index());
}
private:
template <size_t ..._Indices>
_LIBCPP_INLINE_VISIBILITY
void __execute(__tuple_indices<_Indices...>)
{
_STD::move(_STD::get<0>(__f_))(_STD::move(_STD::get<_Indices>(__f_))...);
}
};
#else
template <class _F>
class __call_once_param
{
@ -475,6 +511,8 @@ public:
}
};
#endif
template <class _F>
void
__call_once_proxy(void* __vp)
@ -494,10 +532,9 @@ call_once(once_flag& __flag, _Callable&& __func, _Args&&... __args)
{
if (__builtin_expect(__flag.__state_ , ~0ul) != ~0ul)
{
typedef decltype(std::bind(std::forward<_Callable>(__func),
std::forward<_Args>(__args)...)) _G;
__call_once_param<_G> __p(std::bind(std::forward<_Callable>(__func),
std::forward<_Args>(__args)...));
typedef tuple<typename decay<_Callable>::type, typename decay<_Args>::type...> _G;
__call_once_param<_G> __p(_G(__decay_copy(_STD::forward<_Callable>(__func)),
__decay_copy(_STD::forward<_Args>(__args))...));
__call_once(__flag.__state_, &__p, &__call_once_proxy<_G>);
}
}

View File

@ -129,6 +129,22 @@ void f42()
std::call_once(flg41, init41);
}
#ifndef _LIBCPP_HAS_NO_VARIADICS
class MoveOnly
{
MoveOnly(const MoveOnly&);
public:
MoveOnly() {}
MoveOnly(MoveOnly&&) {}
void operator()(MoveOnly&&)
{
}
};
#endif
int main()
{
// check basic functionality
@ -174,5 +190,9 @@ int main()
t1.join();
assert(init2::called == 5);
}
{
std::once_flag f;
std::call_once(f, MoveOnly(), MoveOnly());
}
#endif // _LIBCPP_HAS_NO_VARIADICS
}