empty_sequence checkin

[SVN r26201]

include/boost/mpl/empty_sequence.hpp

@@ -0,0 +1,42 @@
+
+#ifndef BOOST_MPL_EMPTY_SEQUENCE_HPP_INCLUDED
+#define BOOST_MPL_EMPTY_SEQUENCE_HPP_INCLUDED
+
+// Copyright Aleksey Gurtovoy 2004
+// Copyright Alexander Nasonov 2004
+//
+// Distributed under the Boost Software License, Version 1.0. 
+// (See accompanying file LICENSE_1_0.txt or copy at 
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+// $Source$
+// $Date$
+// $Revision$
+
+#include <boost/mpl/size_fwd.hpp>
+#include <boost/mpl/int.hpp>
+#include <boost/mpl/iterator_tags.hpp>
+
+namespace boost { namespace mpl {
+
+struct empty_sequence
+{
+    struct tag; 
+    struct begin { typedef random_access_iterator_tag category; };    
+    typedef begin end;
+};
+
+template<>
+struct size_impl<empty_sequence::tag>
+{
+    template< typename Sequence > struct apply
+        : int_<0>
+    {
+    };
+};
+
+}}
+
+#endif // #ifndef BOOST_MPL_EMPTY_SEQUENCE_HPP_INCLUDED

test/empty_sequence.cpp

@@ -0,0 +1,36 @@
+
+// Copyright Aleksey Gurtovoy 2004
+// Copyright Alexander Nasonov 2004
+//
+// Distributed under the Boost Software License, Version 1.0. 
+// (See accompanying file LICENSE_1_0.txt or copy at 
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+// $Source$
+// $Date$
+// $Revision$
+
+#include <boost/mpl/empty_sequence.hpp>
+#include <boost/mpl/size.hpp>
+#include <boost/mpl/distance.hpp>
+#include <boost/mpl/advance.hpp>
+#include <boost/mpl/begin_end.hpp>
+#include <boost/mpl/aux_/test.hpp>
+
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/add_pointer.hpp>
+
+MPL_TEST_CASE()
+{
+    typedef begin<empty_sequence>::type begin;
+    typedef end<empty_sequence>::type end;
+
+    MPL_ASSERT(( is_same<begin,end> ));
+    MPL_ASSERT_RELATION( (mpl::distance<begin,end>::value), ==, 0 );
+    MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 );
+
+    typedef advance_c<begin,0>::type advanced;
+    MPL_ASSERT(( is_same<advanced,end> ));
+}