[libcxx] r253274 - Implement P0007: Constant View: A proposal for a std::as_const helper function template.
Marshall Clow via cfe-commits
cfe-commits at lists.llvm.org
Mon Nov 16 16:08:09 PST 2015
Author: marshall
Date: Mon Nov 16 18:08:08 2015
New Revision: 253274
URL: http://llvm.org/viewvc/llvm-project?rev=253274&view=rev
Log:
Implement P0007: Constant View: A proposal for a std::as_const helper function template.
Added:
libcxx/trunk/test/std/utilities/utility/as_const/
libcxx/trunk/test/std/utilities/utility/as_const/as_const.fail.cpp
libcxx/trunk/test/std/utilities/utility/as_const/as_const.pass.cpp
Modified:
libcxx/trunk/include/utility
libcxx/trunk/www/cxx1z_status.html
Modified: libcxx/trunk/include/utility
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?rev=253274&r1=253273&r2=253274&view=diff
==============================================================================
--- libcxx/trunk/include/utility (original)
+++ libcxx/trunk/include/utility Mon Nov 16 18:08:08 2015
@@ -52,6 +52,9 @@ template <class T>
>::type
move_if_noexcept(T& x) noexcept; // constexpr in C++14
+template <class T> constexpr add_const<T>_t& as_const(T& t) noexcept; // C++17
+template <class T> void as_const(const T&&) = delete; // C++17
+
template <class T> typename add_rvalue_reference<T>::type declval() noexcept;
template <class T1, class T2>
@@ -242,6 +245,11 @@ move_if_noexcept(_Tp& __x) _NOEXCEPT
return _VSTD::move(__x);
}
+#if _LIBCPP_STD_VER > 14
+template <class _Tp> constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
+template <class _Tp> void as_const(const _Tp&&) = delete;
+#endif
+
struct _LIBCPP_TYPE_VIS_ONLY piecewise_construct_t { };
#if defined(_LIBCPP_HAS_NO_CONSTEXPR) || defined(_LIBCPP_BUILDING_UTILITY)
extern const piecewise_construct_t piecewise_construct;// = piecewise_construct_t();
Added: libcxx/trunk/test/std/utilities/utility/as_const/as_const.fail.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/utility/as_const/as_const.fail.cpp?rev=253274&view=auto
==============================================================================
--- libcxx/trunk/test/std/utilities/utility/as_const/as_const.fail.cpp (added)
+++ libcxx/trunk/test/std/utilities/utility/as_const/as_const.fail.cpp Mon Nov 16 18:08:08 2015
@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template <class T> constexpr add_const<T>& as_const(T& t) noexcept; // C++17
+// template <class T> add_const<T>& as_const(const T&&) = delete; // C++17
+
+#include <utility>
+
+struct S {int i;};
+
+int main()
+{
+ std::as_const(S{});
+}
Added: libcxx/trunk/test/std/utilities/utility/as_const/as_const.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/utility/as_const/as_const.pass.cpp?rev=253274&view=auto
==============================================================================
--- libcxx/trunk/test/std/utilities/utility/as_const/as_const.pass.cpp (added)
+++ libcxx/trunk/test/std/utilities/utility/as_const/as_const.pass.cpp Mon Nov 16 18:08:08 2015
@@ -0,0 +1,46 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template <class T> constexpr add_const<T>& as_const(T& t) noexcept; // C++17
+// template <class T> add_const<T>& as_const(const T&&) = delete; // C++17
+
+#include <utility>
+#include <cassert>
+
+struct S {int i;};
+bool operator==(const S& x, const S& y) { return x.i == y.i; }
+bool operator==(const volatile S& x, const volatile S& y) { return x.i == y.i; }
+
+template<typename T>
+void test(T& t)
+{
+ static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const (t))>::type>::value, "");
+ static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const< T>(t))>::type>::value, "");
+ static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<const T>(t))>::type>::value, "");
+ static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<volatile T>(t))>::type>::value, "");
+ static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<const volatile T>(t))>::type>::value, "");
+
+ assert(std::as_const(t) == t);
+ assert(std::as_const< T>(t) == t);
+ assert(std::as_const<const T>(t) == t);
+ assert(std::as_const<volatile T>(t) == t);
+ assert(std::as_const<const volatile T>(t) == t);
+}
+
+int main()
+{
+ int i = 3;
+ double d = 4.0;
+ S s{2};
+ test(i);
+ test(d);
+ test(s);
+}
Modified: libcxx/trunk/www/cxx1z_status.html
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/www/cxx1z_status.html?rev=253274&r1=253273&r2=253274&view=diff
==============================================================================
--- libcxx/trunk/www/cxx1z_status.html (original)
+++ libcxx/trunk/www/cxx1z_status.html Mon Nov 16 18:08:08 2015
@@ -73,7 +73,7 @@
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0004R1.html">P0004R1</a></td><td>LWG</td><td>Remove Deprecated iostreams aliases.</td><td>Kona</td><td>Complete</td><td>3.8</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0006R0.html">P0006R0</a></td><td>LWG</td><td>Adopt Type Traits Variable Templates for C++17.</td><td>Kona</td><td>In progress</td><td></td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0092R1.html">P0092R1</a></td><td>LWG</td><td>Polishing <chrono></td><td>Kona</td><td>Complete</td><td>3.8</td></tr>
- <tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0007R1.html">P0007R1</a></td><td>LWG</td><td>Constant View: A proposal for a <tt>std::as_const</tt> helper function template.</td><td>Kona</td><td>In progress</td><td></td></tr>
+ <tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0007R1.html">P0007R1</a></td><td>LWG</td><td>Constant View: A proposal for a <tt>std::as_const</tt> helper function template.</td><td>Kona</td><td>Complete</td><td>3.8</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0156R0.htm" >P0156R0</a></td><td>LWG</td><td>Variadic lock_guard(rev 3).</td><td>Kona</td><td></td><td></td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0074R0.html">P0074R0</a></td><td>LWG</td><td>Making <tt>std::owner_less</tt> more flexible</td><td>Kona</td><td>Complete</td><td>3.8</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/P0013R1.html">P0013R1</a></td><td>LWG</td><td>Logical type traits rev 2</td><td>Kona</td><td>Complete</td><td>3.8</td></tr>
More information about the cfe-commits
mailing list