Check for std::conditional and pull it into the Dune namespace

If not found, our own fallback implementation will be used.

cmake/modules/CMakeLists.txt

@@ -10,6 +10,7 @@ set(modules DuneBoost.cmake
   DuneTestMacros.cmake
   DuneTests.cmake
   FindBoostFusion.cmake
+  FindCXX11Conditional.cmake
   FindCXX11Features.cmake
   FindGMP.cmake
   FindInkscape.cmake

cmake/modules/DuneMacros.cmake

@@ -419,6 +419,7 @@ macro(dune_project)
 
   # set required compiler flags for C++11 (former C++0x)
   find_package(CXX11Features)
+  find_package(CXX11Conditional)
 
   include(DuneCxaDemangle)
 

cmake/modules/FindCXX11Conditional.cmake

+# Module that checks whether the compiler supports
+# C++11 std::conditional.
+#
+# Sets the following variable:
+# HAVE_STD_CONDITIONAL
+#
+# perform tests
+include(CheckCXXSourceCompiles)
+
+check_cxx_source_compiles("
+
+  #include <type_traits>
+
+  int main(void){
+      return std::conditional<true,std::integral_constant<int,0>,void>::type::value;
+  }"
+  HAVE_STD_CONDITIONAL)

cmake/modules/Makefile.am

@@ -10,6 +10,7 @@ MODULES = DuneBoost.cmake \
   DuneTestMacros.cmake    \
   DuneTests.cmake         \
   FindBoostFusion.cmake   \
+  FindCXX11Conditional.cmake \
   FindCXX11Features.cmake \
   FindGMP.cmake           \
   FindInkscape.cmake      \

config.h.cmake

@@ -108,6 +108,9 @@
 /* Define to 1 if you have the <type_traits> header file. */
 #cmakedefine HAVE_TYPE_TRAITS 1
 
+/* Define to 1 if you have the <type_traits> header file. */
+#cmakedefine HAVE_STD_CONDITIONAL 1
+
 /* Define to 1 if the MPI2 Standard is supported */
 #cmakedefine MPI_2 1
 

dune/common/typetraits.hh

@@ -395,6 +395,8 @@ namespace Dune
     typedef T2 Type DUNE_DEPRECATED_MSG("Use Dune::conditional::type instead");
   };
 
+#if DOXYGEN || !HAVE_STD_CONDITIONAL
+
    /**
    * @brief Select a type based on a condition.
    *
@@ -403,7 +405,8 @@ namespace Dune
    * The selected type is accessible through the typedef
    * type.
    *
-   * \note This is a reimplementation of the C++11 stl feature of the same name.
+   * \note If available, this uses C++11 std::conditional, otherwise it provides
+   *       a reimplementation.
    */
   template<bool first, class T1, class T2>
   struct conditional
@@ -423,6 +426,13 @@ namespace Dune
     typedef T2 type;
   };
 
+#else // DOXYGEN || !HAVE_STD_CONDITONAL
+
+  // pull in default implementation
+  using std::conditional;
+
+#endif // DOXYGEN || !HAVE_STD_CONDITONAL
+
   ////////////////////////////////////////////////////////////////////////
   //
   // integral_constant (C++0x 20.7.3 "Helper classes")

m4/CMakeLists.txt

@@ -13,6 +13,7 @@ install(PROGRAMS
         cxx0x_static_assert.m4
         cxx0x_variadic.m4
         cxx0x_variadic_constructor_sfinae.m4
+        cxx11_conditional.m4
         dune.m4
         dune_all.m4
         dune_autobuild.m4

m4/Makefile.am

@@ -17,6 +17,7 @@ ALLM4S = 					\
 	cxx0x_static_assert.m4			\
 	cxx0x_variadic.m4			\
 	cxx0x_variadic_constructor_sfinae.m4    \
+	cxx11_conditional.m4			\
 	dune.m4					\
 	dune_all.m4				\
 	dune_autobuild.m4			\

m4/cxx11_conditional.m4

+# tests for C++11 conditional support
+# the associated macro is called HAVE_STD_CONDITIONAL
+
+AC_DEFUN([CXX11_CONDITIONAL_CHECK],[
+  AC_CACHE_CHECK([for C++11 std::conditional], dune_cv_cxx11_conditional_support, [
+    AC_REQUIRE([AC_PROG_CXX])
+    AC_REQUIRE([GXX0X])
+    AC_LANG_PUSH([C++])
+    AC_RUN_IFELSE([
+      AC_LANG_PROGRAM([
+
+        #include <type_traits>
+
+        ],
+        [
+          return std::conditional<true,std::integral_constant<int,0>,void>::type::value;
+        ])],
+      dune_cv_cxx11_conditional_support=yes,
+      dune_cv_cxx11_conditional_support=no)
+    AC_LANG_POP
+  ])
+  if test "x$dune_cv_cxx11_conditional_support" = xyes; then
+    AC_DEFINE(HAVE_STD_CONDITIONAL, 1, [Define to 1 if C++11 std::conditional is supported])
+  fi
+])

m4/dune_common.m4

@@ -24,6 +24,7 @@ AC_DEFUN([DUNE_COMMON_CHECKS],
   AC_REQUIRE([SHARED_PTR])
   AC_REQUIRE([VARIADIC_TEMPLATES_CHECK])
   AC_REQUIRE([RVALUE_REFERENCES_CHECK])
+  AC_REQUIRE([CXX11_CONDITIONAL_CHECK])
   AC_REQUIRE([DUNE_BOOST_BASE])
   AC_REQUIRE([MAKE_SHARED])
   AC_REQUIRE([DUNE_LINKCXX])