From d5e39913c856b46ba7137a487f2089715c8ee333 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Mon, 26 Jun 2017 16:07:23 +0300
Subject: [PATCH] Add mp_quote_trait

---
 include/boost/mp11/utility.hpp |  6 +++++
 test/Jamfile                   |  1 +
 test/mp_invoke_sf.cpp          | 11 +++++++++
 test/mp_quote.cpp              |  2 +-
 test/mp_quote_trait.cpp        | 41 ++++++++++++++++++++++++++++++++++
 5 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 test/mp_quote_trait.cpp

diff --git a/include/boost/mp11/utility.hpp b/include/boost/mp11/utility.hpp
index bf58361..f82d613 100644
--- a/include/boost/mp11/utility.hpp
+++ b/include/boost/mp11/utility.hpp
@@ -116,6 +116,12 @@ template<template<class...> class F> struct mp_quote
     template<class... T> using fn = typename mp_defer<F, T...>::type;
 };
 
+// mp_quote_trait
+template<template<class...> class F> struct mp_quote_trait
+{
+    template<class... T> using fn = typename F<T...>::type;
+};
+
 // mp_invoke
 #if BOOST_WORKAROUND( BOOST_MSVC, < 1900 )
 
diff --git a/test/Jamfile b/test/Jamfile
index dbcd718..05eefac 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -89,6 +89,7 @@ run mp_defer.cpp : : : $(REQ) ;
 run mp_quote.cpp : : : $(REQ) ;
 run mp_invoke.cpp : : : $(REQ) ;
 run mp_invoke_sf.cpp : : : $(REQ) ;
+run mp_quote_trait.cpp : : : $(REQ) ;
 
 # integer_sequence
 run integer_sequence.cpp : : : $(REQ) ;
diff --git a/test/mp_invoke_sf.cpp b/test/mp_invoke_sf.cpp
index 7c2feb6..f100670 100644
--- a/test/mp_invoke_sf.cpp
+++ b/test/mp_invoke_sf.cpp
@@ -13,7 +13,9 @@
 
 using boost::mp11::mp_invoke;
 using boost::mp11::mp_quote;
+using boost::mp11::mp_quote_trait;
 using boost::mp11::mp_valid;
+using boost::mp11::mp_identity;
 using boost::mp11::mp_identity_t;
 
 int main()
@@ -29,5 +31,14 @@ int main()
     BOOST_TEST_TRAIT_TRUE((mp_valid<mp_invoke, Qi, void>));
     BOOST_TEST_TRAIT_FALSE((mp_valid<mp_invoke, Qi, void, void>));
 
+    using Qt = mp_quote_trait<mp_identity>;
+
+#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, <= 1800 )
+#else
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_invoke, Qt>));
+#endif
+    BOOST_TEST_TRAIT_TRUE((mp_valid<mp_invoke, Qt, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_invoke, Qt, void, void>));
+
     return boost::report_errors();
 }
diff --git a/test/mp_quote.cpp b/test/mp_quote.cpp
index 9d2ca6a..0e5d1a5 100644
--- a/test/mp_quote.cpp
+++ b/test/mp_quote.cpp
@@ -1,5 +1,5 @@
 
-//  Copyright 2015, 2017 Peter Dimov.
+// Copyright 2015, 2017 Peter Dimov.
 //
 // Distributed under the Boost Software License, Version 1.0.
 //
diff --git a/test/mp_quote_trait.cpp b/test/mp_quote_trait.cpp
new file mode 100644
index 0000000..dd0018c
--- /dev/null
+++ b/test/mp_quote_trait.cpp
@@ -0,0 +1,41 @@
+
+// Copyright 2015, 2017 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>
+
+int main()
+{
+    using boost::mp11::mp_identity;
+    using boost::mp11::mp_quote_trait;
+    using boost::mp11::mp_invoke;
+
+    {
+        using Q = mp_quote_trait<mp_identity>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<Q::fn<void>, void>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<Q::fn<int[]>, int[]>));
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_invoke<Q, void>, void>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_invoke<Q, int[]>, int[]>));
+    }
+
+    {
+        using Q = mp_quote_trait<std::add_const>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<Q::fn<void>, void const>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<Q::fn<int[]>, int const[]>));
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_invoke<Q, void>, void const>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_invoke<Q, int[]>, int const[]>));
+    }
+
+    return boost::report_errors();
+}