Updated boost to v1.55.0

[rsem.git] / boost / utility / declval.hpp

diff --git a/boost/utility/declval.hpp b/boost/utility/declval.hpp
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+//  declval.hpp  -------------------------------------------------------------//
+
+//  Copyright 2010 Vicente J. Botet Escriba
+
+//  Distributed under the Boost Software License, Version 1.0.
+//  See http://www.boost.org/LICENSE_1_0.txt
+
+#ifndef BOOST_UTILITY_DECLVAL_HPP
+#define BOOST_UTILITY_DECLVAL_HPP
+
+#include <boost/config.hpp>
+
+//----------------------------------------------------------------------------//
+
+#include <boost/type_traits/add_rvalue_reference.hpp>
+
+//----------------------------------------------------------------------------//
+//                                                                            //
+//                           C++03 implementation of                          //
+//                   20.2.4 Function template declval [declval]               //
+//                          Written by Vicente J. Botet Escriba               //
+//                                                                            //
+// 1 The library provides the function template declval to simplify the
+// definition of expressions which occur as unevaluated operands.
+// 2 Remarks: If this function is used, the program is ill-formed.
+// 3 Remarks: The template parameter T of declval may be an incomplete type.
+// [ Example:
+//
+// template <class To, class From>
+// decltype(static_cast<To>(declval<From>())) convert(From&&);
+//
+// declares a function template convert which only participates in overloading
+// if the type From can be explicitly converted to type To. For another example
+// see class template common_type (20.9.7.6). -end example ]
+//----------------------------------------------------------------------------//
+
+namespace boost {
+
+    template <typename T>
+    typename add_rvalue_reference<T>::type declval() BOOST_NOEXCEPT; // as unevaluated operand
+
+}  // namespace boost
+
+#endif  // BOOST_UTILITY_DECLVAL_HPP