[cfe-commits] [libcxx] r113225 - in /libcxx/trunk: include/type_traits test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp
Howard Hinnant
hhinnant at apple.com
Tue Sep 7 10:47:31 PDT 2010
Author: hhinnant
Date: Tue Sep 7 12:47:31 2010
New Revision: 113225
URL: http://llvm.org/viewvc/llvm-project?rev=113225&view=rev
Log:
Made a stab at has_default_constructor. Got it mostly working for g++-4.0, but only works for scalar types on clang. Ultimately this needs a compiler-supported is_constructible which clang is missing, and won't be able to use until it gets variadic templates.
Modified:
libcxx/trunk/include/type_traits
libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp
libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp
Modified: libcxx/trunk/include/type_traits
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/type_traits?rev=113225&r1=113224&r2=113225&view=diff
==============================================================================
--- libcxx/trunk/include/type_traits (original)
+++ libcxx/trunk/include/type_traits Tue Sep 7 12:47:31 2010
@@ -1637,6 +1637,80 @@
: public false_type
{};
+template <class _Tp>
+struct has_default_constructor
+ : public is_constructible<_Tp>
+ {};
+
+#else // _LIBCPP_HAS_NO_ADVANCED_SFINAE
+
+// template <class T> struct is_constructible0;
+
+// main is_constructible0 test
+
+template <class _Tp>
+decltype((_STD::move(_Tp()), true_type()))
+__is_constructible0_test(_Tp&);
+
+false_type
+__is_constructible0_test(__any);
+
+template <bool, class _Tp>
+struct __is_constructible0_imp // false, _Tp is not a scalar
+ : public common_type
+ <
+ decltype(__is_constructible0_test(declval<_Tp&>()))
+ >::type
+ {};
+
+// handle scalars and reference types
+
+// Scalars are default constructible, references are not
+
+template <class _Tp>
+struct __is_constructible0_imp<true, _Tp>
+ : public is_scalar<_Tp>
+ {};
+
+// Treat scalars and reference types separately
+
+template <bool, class _Tp>
+struct __is_constructible0_void_check
+ : public __is_constructible0_imp<is_scalar<_Tp>::value || is_reference<_Tp>::value,
+ _Tp>
+ {};
+
+// If any of T or Args is void, is_constructible should be false
+
+template <class _Tp>
+struct __is_constructible0_void_check<true, _Tp>
+ : public false_type
+ {};
+
+// has_default_constructor entry point
+
+template <class _Tp>
+struct has_default_constructor
+ : public __is_constructible0_void_check<is_void<_Tp>::value
+ || is_abstract<_Tp>::value,
+ _Tp>
+ {};
+
+// Array types are default constructible if their element type
+// is default constructible
+
+template <class _A, size_t _N>
+struct __is_constructible0_imp<false, _A[_N]>
+ : public has_default_constructor<typename remove_all_extents<_A>::type>
+ {};
+
+// Incomplete array types are not constructible
+
+template <class _A>
+struct __is_constructible0_imp<false, _A[]>
+ : public false_type
+ {};
+
#endif // _LIBCPP_HAS_NO_ADVANCED_SFINAE
template <class _Tp> struct __is_zero_default_constructible
Modified: libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp?rev=113225&r1=113224&r2=113225&view=diff
==============================================================================
--- libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp (original)
+++ libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_default_constructor.pass.cpp Tue Sep 7 12:47:31 2010
@@ -13,7 +13,58 @@
#include <type_traits>
+template <class T, bool Result>
+void test_has_default_constructor()
+{
+ static_assert(std::has_default_constructor<T>::value == Result, "");
+ static_assert(std::has_default_constructor<const T>::value == Result, "");
+ static_assert(std::has_default_constructor<volatile T>::value == Result, "");
+ static_assert(std::has_default_constructor<const volatile T>::value == Result, "");
+}
+
+class Empty
+{
+};
+
+class NotEmpty
+{
+public:
+ virtual ~NotEmpty();
+};
+
+union Union {};
+
+struct bit_zero
+{
+ int : 0;
+};
+
+class Abstract
+{
+public:
+ virtual ~Abstract() = 0;
+};
+
+struct A
+{
+ A();
+};
+
int main()
{
-#error has_default_constructor not implemented
+ test_has_default_constructor<void, false>();
+ test_has_default_constructor<int&, false>();
+ test_has_default_constructor<char[], false>();
+ test_has_default_constructor<Abstract, false>();
+
+ test_has_default_constructor<A, true>();
+ test_has_default_constructor<Union, true>();
+ test_has_default_constructor<Empty, true>();
+ test_has_default_constructor<int, true>();
+ test_has_default_constructor<double, true>();
+ test_has_default_constructor<int*, true>();
+ test_has_default_constructor<const int*, true>();
+ test_has_default_constructor<char[3], true>();
+ test_has_default_constructor<NotEmpty, true>();
+ test_has_default_constructor<bit_zero, true>();
}
Modified: libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp?rev=113225&r1=113224&r2=113225&view=diff
==============================================================================
--- libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp (original)
+++ libcxx/trunk/test/utilities/meta/meta.unary/meta.unary.prop/has_nothrow_default_constructor.pass.cpp Tue Sep 7 12:47:31 2010
@@ -37,6 +37,7 @@
class NotEmpty
{
+public:
virtual ~NotEmpty();
};
@@ -49,6 +50,7 @@
class Abstract
{
+public:
virtual ~Abstract() = 0;
};
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