Add mp_quote, mp_unquote.

include/boost/mp11/utility.hpp

@@ -101,6 +101,30 @@ struct mp_no_type
 
 template<template<class...> class F, class... T> using mp_defer = mp_if<mp_valid<F, T...>, detail::mp_defer_impl<F, T...>, detail::mp_no_type>;
 
+// mp_quote
+template<template<class...> class F> struct mp_quote
+{
+    template<class... T> using apply = F<T...>;
+};
+
+// mp_unquote
+namespace detail
+{
+
+template<class Q, class... T> struct mp_unquote_impl
+{
+    using type = typename Q::template apply<T...>;
+};
+
+template<template<class...> class F, class... T> struct mp_unquote_impl<mp_quote<F>, T...>
+{
+    using type = F<T...>;
+};
+
+} // namespace detail
+
+template<class Q, class... T> using mp_unquote = typename detail::mp_unquote_impl<Q, T...>::type;
+
 } // namespace boost
 
 #endif // #ifndef BOOST_MP11_UTILITY_HPP_INCLUDED

test/Jamfile.v2

@@ -66,6 +66,7 @@ run mp_if.cpp : : : $(REQ) ;
 run mp_eval_if.cpp : : : $(REQ) ;
 run mp_valid.cpp : : : $(REQ) ;
 run mp_defer.cpp : : : $(REQ) ;
+run mp_quote.cpp : : : $(REQ) ;
 
 # integer_sequence
 run integer_sequence.cpp : : : $(REQ) ;

test/mp_quote.cpp

@@ -0,0 +1,28 @@
+
+//  Copyright 2015 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+
+#include <boost/mp11/utility.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
+
+struct X {};
+
+int main()
+{
+    using boost::mp_identity_t;
+    using boost::mp_quote;
+    using boost::mp_unquote;
+
+    using Q = mp_quote<mp_identity_t>;
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_unquote<Q, void>, void>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_unquote<Q, int[]>, int[]>));
+
+    return boost::report_errors();
+}