[libcxx] r185863 - Implement n3668 - std::exchange
Marshall Clow
mclow.lists at gmail.com
Mon Jul 8 13:54:40 PDT 2013
Author: marshall
Date: Mon Jul 8 15:54:40 2013
New Revision: 185863
URL: http://llvm.org/viewvc/llvm-project?rev=185863&view=rev
Log:
Implement n3668 - std::exchange
Added:
libcxx/trunk/test/utilities/utility/exchange/
libcxx/trunk/test/utilities/utility/exchange/exchange.pass.cpp
Modified:
libcxx/trunk/include/utility
Modified: libcxx/trunk/include/utility
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/utility?rev=185863&r1=185862&r2=185863&view=diff
==============================================================================
--- libcxx/trunk/include/utility (original)
+++ libcxx/trunk/include/utility Mon Jul 8 15:54:40 2013
@@ -138,6 +138,8 @@ template<size_t N>
template<class... T>
using index_sequence_for = make_index_sequence<sizeof...(T)>;
+template<class T, class U=T>
+ T exchange(T& obj, U&& new_value);
} // std
*/
@@ -685,6 +687,17 @@ template<class... _Tp>
#endif // _LIBCPP_STD_VER > 11
+#if _LIBCPP_STD_VER > 11
+template<class _T1, class _T2 = _T1>
+_LIBCPP_INLINE_VISIBILITY inline
+_T1 exchange(_T1& __obj, _T2 && __new_value)
+{
+ _T1 __old_value = _VSTD::move(__obj);
+ __obj = _VSTD::forward<_T2>(__new_value);
+ return __old_value;
+}
+#endif // _LIBCPP_STD_VER > 11
+
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_UTILITY
Added: libcxx/trunk/test/utilities/utility/exchange/exchange.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/utility/exchange/exchange.pass.cpp?rev=185863&view=auto
==============================================================================
--- libcxx/trunk/test/utilities/utility/exchange/exchange.pass.cpp (added)
+++ libcxx/trunk/test/utilities/utility/exchange/exchange.pass.cpp Mon Jul 8 15:54:40 2013
@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+
+// utilities
+
+// exchange
+
+#include <utility>
+#include <cassert>
+#include <string>
+
+int main()
+{
+#if _LIBCPP_STD_VER > 11
+ {
+ int v = 12;
+ assert ( std::exchange ( v, 23 ) == 12 );
+ assert ( v == 23 );
+ assert ( std::exchange ( v, 67.2 ) == 23 );
+ assert ( v = 67 );
+ }
+
+ {
+ bool b = false;
+ assert ( !std::exchange ( b, true ));
+ assert ( b );
+ }
+
+ {
+ const std::string s1 ( "Hi Mom!" );
+ const std::string s2 ( "Yo Dad!" );
+ std::string s3 = s1; // Mom
+ assert ( std::exchange ( s3, s2 ) == s1 );
+ assert ( s3 == s2 );
+ assert ( std::exchange ( s3, "Hi Mom!" ) == s2 );
+ assert ( s3 == s1 );
+ assert ( std::exchange ( s3, "" ) == s1 );
+ assert ( s3.size () == 0 );
+ }
+#endif
+}
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