Adding the Tuple library files

[SVN r10828]

include/boost/tuple/reference_wrappers.hpp

@@ -0,0 +1,57 @@
+// -- reference_wrappers - Boost Tuple Library -----------------------------
+
+// Copyright (C) 1999, 2000 Jaakko J<>rvi (jaakko.jarvi@cs.utu.fi)
+//
+// Permission to copy, use, sell and distribute this software is granted
+// provided this copyright notice appears in all copies. 
+// Permission to modify the code and to distribute modified code is granted
+// provided this copyright notice appears in all copies, and a notice 
+// that the code was modified is included with the copyright notice.
+//
+// This software is provided "as is" without express or implied warranty, 
+// and with no claim as to its suitability for any purpose.
+//
+// For more information, see http://www.boost.org 
+
+// ----------------------------------------------------------------- 
+
+#ifndef BOOST_TUPLE_REFERENCE_WRAPPERS_HPP
+#define BOOST_TUPLE_REFERENCE_WRAPPERS_HPP
+
+namespace boost {
+
+
+// reference wrappers -------------------------------------------------------
+  
+// These wrappers are handle classes that hold references to objects.
+
+// reference_wrapper is used to specify that a tuple element should be 
+// a reference to the wrapped object - rather than a copy of it.
+// The wrapper acts as a disguise for passing non-const reference 
+// parameters via a reference to const parameter.
+
+template<class T>
+class reference_wrapper { 
+  T& x; 
+public:
+  explicit 
+  reference_wrapper(T& t) : x(t) {} 
+  operator T&() const { return x; }
+};
+
+// store as a reference to T
+template<class T> 
+inline const reference_wrapper<T> ref(T& t) { 
+  return reference_wrapper<T>(t); 
+}
+
+// store as a reference to const T
+template<class T> 
+inline const reference_wrapper<const T> cref(const T& t) {
+  return reference_wrapper<const T>(t); 
+}
+   
+} // end of namespace boost
+
+
+#endif	// BOOST_TUPLE_REFERENCE_WRAPPERS_HPP