initial commit

[SVN r18350]

include/boost/implicit_cast.hpp

@@ -0,0 +1,36 @@
+// Copyright David Abrahams 2003. Permission to copy, use,
+// modify, sell and distribute this software is granted provided this
+// copyright notice appears in all copies. This software is provided
+// "as is" without express or implied warranty, and with no claim as
+// to its suitability for any purpose.
+#ifndef IMPLICIT_CAST_DWA200356_HPP
+# define IMPLICIT_CAST_DWA200356_HPP
+
+# include <boost/mpl/identity.hpp>
+
+namespace boost {
+
+// implementation originally suggested by C. Green in
+// http://lists.boost.org/MailArchives/boost/msg00886.php
+
+// The use of identity creates a non-deduced form, so that the
+// explicit template argument must be supplied
+template <typename T>
+inline T implicit_cast (typename mpl::identity<T>::type x) {
+    return x;
+}
+
+// incomplete return type now is here
+//template <typename T>
+//void implicit_cast (...);
+
+// Macro for when you need a constant expression (Gennaro Prota)
+#define BOOST_IMPLICIT_CAST(dst_type, expr)           \
+          ( sizeof( implicit_cast<dst_type>(expr) )   \
+                     ,                                \
+            static_cast<dst_type>(expr)               \
+          )
+
+} // namespace boost
+
+#endif // IMPLICIT_CAST_DWA200356_HPP