[libcxx] r189831 - LWG Issue 2148: Hashing Enums
Marshall Clow
mclow.lists at gmail.com
Tue Sep 3 10:55:32 PDT 2013
Author: marshall
Date: Tue Sep 3 12:55:32 2013
New Revision: 189831
URL: http://llvm.org/viewvc/llvm-project?rev=189831&view=rev
Log:
LWG Issue 2148: Hashing Enums
Added:
libcxx/trunk/test/utilities/function.objects/unord.hash/enum.fail.cpp
libcxx/trunk/test/utilities/function.objects/unord.hash/enum.pass.cpp
Modified:
libcxx/trunk/include/functional
libcxx/trunk/www/cxx1y_status.html
Modified: libcxx/trunk/include/functional
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/functional?rev=189831&r1=189830&r2=189831&view=diff
==============================================================================
--- libcxx/trunk/include/functional (original)
+++ libcxx/trunk/include/functional Tue Sep 3 12:55:32 2013
@@ -2399,6 +2399,22 @@ struct _LIBCPP_TYPE_VIS_ONLY hash<long d
}
};
+#if _LIBCPP_STD_VER > 11
+template <class _Tp>
+struct _LIBCPP_TYPE_VIS_ONLY hash
+ : public unary_function<_Tp, size_t>
+{
+ static_assert(is_enum<_Tp>::value, "This hash only works for enumeration types");
+
+ _LIBCPP_INLINE_VISIBILITY
+ size_t operator()(_Tp __v) const _NOEXCEPT
+ {
+ typedef typename underlying_type<_Tp>::type type;
+ return hash<type>{}(static_cast<type>(__v));
+ }
+};
+#endif
+
// struct hash<T*> in <memory>
_LIBCPP_END_NAMESPACE_STD
Added: libcxx/trunk/test/utilities/function.objects/unord.hash/enum.fail.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/function.objects/unord.hash/enum.fail.cpp?rev=189831&view=auto
==============================================================================
--- libcxx/trunk/test/utilities/function.objects/unord.hash/enum.fail.cpp (added)
+++ libcxx/trunk/test/utilities/function.objects/unord.hash/enum.fail.cpp Tue Sep 3 12:55:32 2013
@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+
+// <functional>
+
+// Hashing a struct w/o a defined hash should fail.
+
+#include <functional>
+#include <cassert>
+#include <type_traits>
+
+struct X {};
+
+int main()
+{
+ X x;
+ size_t h = std::hash<X>{} ( x );
+}
Added: libcxx/trunk/test/utilities/function.objects/unord.hash/enum.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/function.objects/unord.hash/enum.pass.cpp?rev=189831&view=auto
==============================================================================
--- libcxx/trunk/test/utilities/function.objects/unord.hash/enum.pass.cpp (added)
+++ libcxx/trunk/test/utilities/function.objects/unord.hash/enum.pass.cpp Tue Sep 3 12:55:32 2013
@@ -0,0 +1,63 @@
+//===----------------------------------------------------------------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+
+// <functional>
+
+// make sure that we can hash enumeration values
+// Not very portable
+
+#include <__config>
+
+#if _LIBCPP_STD_VER > 11
+
+#include <functional>
+#include <cassert>
+#include <type_traits>
+#include <limits>
+
+enum class Colors { red, orange, yellow, green, blue, indigo, violet };
+enum class Cardinals { zero, one, two, three, five=5 };
+enum class LongColors : short { red, orange, yellow, green, blue, indigo, violet };
+enum class ShortColors : long { red, orange, yellow, green, blue, indigo, violet };
+enum class EightBitColors : uint8_t { red, orange, yellow, green, blue, indigo, violet };
+
+enum Fruits { apple, pear, grape, mango, cantaloupe };
+
+template <class T>
+void
+test()
+{
+ static_assert((std::is_base_of<std::unary_function<T, std::size_t>,
+ std::hash<T> >::value), "");
+ typedef typename std::underlying_type<T>::type under_type;
+
+ std::hash<T> h1;
+ std::hash<under_type> h2;
+ for (int i = 0; i <= 5; ++i)
+ {
+ T t(static_cast<T> (i));
+ if (sizeof(T) <= sizeof(std::size_t))
+ assert(h1(t) == h2(static_cast<under_type>(i)));
+ }
+}
+
+int main()
+{
+ test<Cardinals>();
+
+ test<Colors>();
+ test<ShortColors>();
+ test<LongColors>();
+ test<EightBitColors>();
+
+ test<Fruits>();
+}
+#else
+int main () {}
+#endif
Modified: libcxx/trunk/www/cxx1y_status.html
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/www/cxx1y_status.html?rev=189831&r1=189830&r2=189831&view=diff
==============================================================================
--- libcxx/trunk/www/cxx1y_status.html (original)
+++ libcxx/trunk/www/cxx1y_status.html Tue Sep 3 12:55:32 2013
@@ -145,7 +145,7 @@
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2128">2128</a></td><td>Absence of global functions cbegin/cend</td><td>Bristol</td><td>Complete</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2145">2145</a></td><td>error_category default constructor</td><td>Bristol</td><td>Complete</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2147">2147</a></td><td>Unclear hint type in Allocator's allocate function</td><td>Bristol</td><td>Complete</td></tr>
- <tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2148">2148</a></td><td>Hashing enums should be supported directly by std::hash</td><td>Bristol</td><td></td></tr>
+ <tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2148">2148</a></td><td>Hashing enums should be supported directly by std::hash</td><td>Bristol</td><td>Complete</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2149">2149</a></td><td>Concerns about 20.8/5</td><td>Bristol</td><td>Complete</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2162">2162</a></td><td>allocator_traits::max_size missing noexcept</td><td>Bristol</td><td>Complete</td></tr>
<tr><td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2163">2163</a></td><td>nth_element requires inconsistent post-conditions</td><td>Bristol</td><td>Complete</td></tr>
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