add 'as_sequence'

[SVN r16417]

include/boost/mpl/as_sequence.hpp

@@ -0,0 +1,49 @@
+//-----------------------------------------------------------------------------
+// boost mpl/as_sequence.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2002
+// Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+
+#ifndef BOOST_MPL_AS_SEQUENCE_HPP_INCLUDED
+#define BOOST_MPL_AS_SEQUENCE_HPP_INCLUDED
+
+#include "boost/mpl/is_sequence.hpp"
+#include "boost/mpl/single_view.hpp"
+#include "boost/mpl/if.hpp"
+#include "boost/mpl/aux_/void_spec.hpp"
+#include "boost/mpl/aux_/lambda_support.hpp"
+#include "boost/mpl/aux_/config/eti.hpp"
+
+namespace boost { namespace mpl {
+
+template<
+      typename BOOST_MPL_AUX_VOID_SPEC_PARAM(T)
+    >
+struct as_sequence
+    : if_< is_sequence<T>, T, single_view<T> >
+{
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(1,as_sequence,(T))
+};
+
+#if defined(BOOST_MPL_MSVC_ETI_BUG)
+template<> struct as_sequence<int>
+{
+    typedef single_view<int> type;
+};
+#endif
+
+BOOST_MPL_AUX_VOID_SPEC(1, as_sequence)
+
+}} // namespace boost::mpl
+
+#endif // BOOST_MPL_AS_SEQUENCE_HPP_INCLUDED

test/Jamfile

@@ -9,6 +9,7 @@ compile always.cpp ;
 compile apply.cpp ;
 compile apply_if.cpp ;
 compile arithmetic.cpp ;
+compile as_sequence.cpp ;
 compile assert_is_same.cpp ;
 compile at.cpp ;
 compile back.cpp ;
@@ -39,6 +40,7 @@ compile insert.cpp ;
 compile insert_range.cpp ;
 compile int_c.cpp ;
 compile integral_c.cpp ;
+compile is_sequence.cpp ;
 compile joint_view.cpp ;
 compile lambda.cpp ;
 compile lambda_args.cpp ;

test/as_sequence.cpp

@@ -0,0 +1,32 @@
+//-----------------------------------------------------------------------------
+// boost mpl/test/as_sequence.cpp source file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2000-02
+// Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+
+#include "boost/mpl/vector.hpp"
+#include "boost/mpl/as_sequence.hpp"
+#include "boost/static_assert.hpp"
+
+using namespace boost::mpl;
+
+struct UDT {};
+
+int main()
+{
+    BOOST_STATIC_ASSERT(is_sequence< as_sequence<int>::type >::value);
+    BOOST_STATIC_ASSERT(is_sequence< as_sequence<UDT>::type >::value);
+    BOOST_STATIC_ASSERT(is_sequence< as_sequence< vector<> >::type >::value);
+
+    return 0;
+}