nullptr as proposed in

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf

[[Imported from SVN: r5308]]

common/nullptr.hh

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+#ifndef DUNE_NULLPTR_HH
+#define DUNE_NULLPTR_HH
+
+#if ! HAVE_NULLPTR
+
+/**
+   \brief Fallback implementation of nullptr
+
+   see C++ proposal
+   http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf
+ */
+const                        // this is a const object...
+class nullptr_t {            // of type nullptr_t
+public:
+  template<class T>          // convertible to any type
+  operator T*() const        // of null non-member
+  { return 0; }              // pointer...
+  template<class C, class T> // or any type of null
+  operator T C::*() const    // member pointer...
+  { return 0; }
+private:
+  void operator&() const;    // whose address can't be taken
+} nullptr = {};              // and whose name is nullptr
+
+#endif // HAVE_NULLPTR
+
+#endif // DUNE_NULLPTR_HH

common/test/Makefile.am

@@ -5,7 +5,7 @@ TESTPROGS = parsetest test-stack arraylisttest smartpointertest \
 	poolallocatortest settest gcdlcmtest streamtest \
 	bigunsignedinttest mpihelpertest singletontest mpicollcomm \
 	utilitytest lrutest \
-	smallobject \
+	smallobject nullptr-test \
 	testfassign1 testfassign2 testfassign3 \
 	testfassign4 \
     testfassign_fail1 testfassign_fail2 testfassign_fail3 \
@@ -14,7 +14,7 @@ TESTPROGS = parsetest test-stack arraylisttest smartpointertest \
 # which tests to run
 COMPILE_XFAIL=$(DUNE_COMMON_ROOT)/bin/xfail-compile-tests
 
-COMPILE_XFAIL_TESTS = static_assert_test
+COMPILE_XFAIL_TESTS = nullptr-test-fail static_assert_test
 
 compile_XFAIL:
 	for i in $(COMPILE_XFAIL_TESTS); do \
@@ -40,6 +40,10 @@ AM_LDFLAGS = $(LOCAL_LIBS)
 # define the programs
 smallobject_SOURCES = smallobject.cc
 
+nullptr_test_SOURCES = nullptr-test.cc nullptr-test2.cc
+nullptr_test_fail_SOURCES = nullptr-test.cc
+nullptr_test_fail_CPPFLAGS = -DFAIL
+
 static_assert_test_SOURCES = static_assert_test.cc
 
 bigunsignedinttest_SOURCES=bigunsignedinttest.cc

common/test/nullptr-test.cc

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+#include <config.h>
+
+#include <dune/common/nullptr.hh>
+
+void basic_tests()
+{
+  typedef nullptr_t NULLPTR_T;
+  char* ch = nullptr;    // ch has the null pointer value
+  char* ch2 = 0;         // ch2 has the null pointer value
+#ifdef FAIL
+  int n = nullptr;       // error
+#endif
+  int n2 = 0;            // n2 is zero
+  if( ch == 0 ) ;        // evaluates to true
+  if( ch == nullptr ) ;  // evaluates to true
+  if( ch ) ;             // evaluates to false
+  if( n2 == 0 ) ;        // evaluates to true
+  ch = ch2;
+#ifdef FAIL
+  if( n2 == nullptr ) ;  // error
+  if( nullptr ) ;        // error, no conversion to bool
+  if( nullptr == 0 ) ;   // error
+  // arithmetic
+  nullptr = 0;           // error, nullptr is not an lvalue
+  nullptr + 2;           // error
+#endif
+}
+
+int main()
+{
+  basic_tests();
+  return 0;
+}

common/test/nullptr-test2.cc

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+#include <config.h>
+
+#include <dune/common/nullptr.hh>

m4/dune_common.m4

@@ -11,6 +11,7 @@ AC_DEFUN([DUNE_COMMON_CHECKS],
   AC_REQUIRE([DUNE_CHECK_COMPILER])
   AC_REQUIRE([GXX0X])
   AC_REQUIRE([STATIC_ASSERT_CHECK])
+  AC_REQUIRE([NULLPTR_CHECK])
   AC_REQUIRE([DUNE_LINKCXX])
   AC_REQUIRE([DUNE_CHECKDEPRECATED])
   AC_REQUIRE([DUNE_SET_MINIMAL_DEBUG_LEVEL])

m4/static_assert.m4

@@ -33,3 +33,21 @@ AC_DEFUN([STATIC_ASSERT_CHECK],[
   fi
   AC_LANG_POP
 ])
+
+AC_DEFUN([NULLPTR_CHECK],[
+  AC_REQUIRE([AC_PROG_CXX])
+  AC_REQUIRE([GXX0X])
+  AC_LANG_PUSH([C++])
+  AC_MSG_CHECKING([whether nullptr is supported])
+  AC_TRY_COMPILE([],[typedef nullptr_t peng;
+    char* ch = nullptr;
+    ], [
+    HAVE_NULLPTR=yes
+    AC_MSG_RESULT(yes)], [
+    HAVE_NULLPTR=no
+    AC_MSG_RESULT(no)])
+  if test "x$HAVE_NULLPTR" = xyes; then
+    AC_DEFINE(HAVE_NULLPTR, 1, [Define to 1 if nullptr is supported])
+  fi
+  AC_LANG_POP
+])