mpl_v2 branch checkin

[SVN r15258]

include/boost/utility/value_init.hpp

@@ -0,0 +1,82 @@
+// (C) 2002, Fernando Luis Cacciola Carballal.
+//
+// This material is provided "as is", with absolutely no warranty expressed
+// or implied. Any use is at your own risk.
+//
+// Permission to use or copy this software for any purpose is hereby granted
+// without fee, provided the above notices are retained on all copies.
+// Permission to modify the code and to distribute modified code is granted,
+// provided the above notices are retained, and a notice that the code was
+// modified is included with the above copyright notice.
+//
+// 21 Ago 2002 (Created) Fernando Cacciola
+//
+#ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
+#define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
+
+#include "boost/detail/select_type.hpp"
+#include "boost/type_traits/cv_traits.hpp"
+
+namespace boost {
+
+namespace vinit_detail {
+
+template<class T>
+class const_T_base
+{
+  protected :
+
+   const_T_base() : x() {}
+
+   T x ;
+} ;
+
+template<class T>
+struct non_const_T_base
+{
+  protected :
+
+   non_const_T_base() : x() {}
+
+   mutable T x ;
+} ;
+
+template<class T>
+struct select_base
+{
+  typedef typename
+    detail::if_true< ::boost::is_const<T>::value >
+      ::template then< const_T_base<T>, non_const_T_base<T> >::type type ;
+} ;
+
+} // namespace vinit_detail
+
+template<class T>
+class value_initialized : vinit_detail::select_base<T>::type
+{
+  public :
+
+    value_initialized() {}
+
+    operator T&() const { return this->x ; }
+
+    T& data() const { return this->x ; }
+
+} ;
+
+template<class T>
+T const& get ( value_initialized<T> const& x )
+{
+  return x.data() ;
+}
+template<class T>
+T& get ( value_initialized<T>& x )
+{
+  return x.data() ;
+}
+
+} // namespace boost
+
+
+#endif
+