From e4c12368c6bc2e8fd3fb653412df46d185184a97 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Sat, 21 Oct 2017 21:51:14 +0300
Subject: [PATCH] Add mp_replace_if_q

---
 doc/mp11/algorithm.adoc          |  7 ++++
 include/boost/mp11/algorithm.hpp |  6 ++++
 test/Jamfile                     |  1 +
 test/mp_replace_if_q.cpp         | 59 ++++++++++++++++++++++++++++++++
 4 files changed, 73 insertions(+)
 create mode 100644 test/mp_replace_if_q.cpp

diff --git a/doc/mp11/algorithm.adoc b/doc/mp11/algorithm.adoc
index aa6723e..4a44995 100644
--- a/doc/mp11/algorithm.adoc
+++ b/doc/mp11/algorithm.adoc
@@ -396,6 +396,13 @@ Replaces all `T` elements of `L` for which `mp_to_bool<P<T>>` is `mp_true` with
 |*mp_replace_if<L1, P, W>*|A~1~|W|...|A~n~
 |===
 
+## mp_replace_if_q<L, Q, W>
+
+    template<class L, class Q, class W> using mp_replace_if_q =
+        mp_replace_if<L, Q::template fn, W>;
+
+As `mp_replace_if`, but takes a quoted metafunction.
+
 ## mp_replace_at_c<L, I, W>
 
     template<class L, std::size_t I, class W> using mp_replace_at_c = /*...*/;
diff --git a/include/boost/mp11/algorithm.hpp b/include/boost/mp11/algorithm.hpp
index a0f246e..44130d2 100644
--- a/include/boost/mp11/algorithm.hpp
+++ b/include/boost/mp11/algorithm.hpp
@@ -378,13 +378,19 @@ template<class L, template<class...> class P, class W> struct mp_replace_if_impl
 
 template<template<class...> class L, class... T, template<class...> class P, class W> struct mp_replace_if_impl<L<T...>, P, W>
 {
+#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, < 1920 )
+    template<class U> struct _f { using type = mp_if<P<U>, W, U>; };
+    using type = L<typename _f<T>::type...>;
+#else
     template<class U> using _f = mp_if<P<U>, W, U>;
     using type = L<_f<T>...>;
+#endif
 };
 
 } // namespace detail
 
 template<class L, template<class...> class P, class W> using mp_replace_if = typename detail::mp_replace_if_impl<L, P, W>::type;
+template<class L, class Q, class W> using mp_replace_if_q = mp_replace_if<L, Q::template fn, W>;
 
 // mp_copy_if<L, P>
 namespace detail
diff --git a/test/Jamfile b/test/Jamfile
index bebab98..9c95adf 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -55,6 +55,7 @@ run mp_at_sf.cpp ;
 run mp_take.cpp ;
 run mp_replace.cpp ;
 run mp_replace_if.cpp ;
+run mp_replace_if_q.cpp ;
 run mp_copy_if.cpp ;
 run mp_remove.cpp ;
 run mp_remove_if.cpp ;
diff --git a/test/mp_replace_if_q.cpp b/test/mp_replace_if_q.cpp
new file mode 100644
index 0000000..a692673
--- /dev/null
+++ b/test/mp_replace_if_q.cpp
@@ -0,0 +1,59 @@
+
+// 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/algorithm.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/utility.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
+#include <tuple>
+#include <utility>
+
+struct X1 {};
+
+int main()
+{
+    using boost::mp11::mp_list;
+    using boost::mp11::mp_replace_if_q;
+    using boost::mp11::mp_quote;
+
+    {
+        using L1 = mp_list<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L1, mp_quote<std::is_const>, void>, L1>));
+
+        using L2 = mp_list<X1, X1 const, X1*, X1 const, X1*, X1*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_volatile>, void>, L2>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_const>, void>, mp_list<X1, void, X1*, void, X1*, X1*>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_pointer>, void>, mp_list<X1, X1 const, void, X1 const, void, void>>));
+    }
+
+    {
+        using L1 = std::tuple<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L1, mp_quote<std::is_const>, void>, L1>));
+
+        using L2 = std::tuple<X1, X1 const, X1*, X1 const, X1*, X1*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_volatile>, void>, L2>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_const>, void>, std::tuple<X1, void, X1*, void, X1*, X1*>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_pointer>, void>, std::tuple<X1, X1 const, void, X1 const, void, void>>));
+    }
+
+    {
+        using L2 = std::pair<X1 const, X1*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_volatile>, void>, L2>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_const>, void>, std::pair<void, X1*>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_replace_if_q<L2, mp_quote<std::is_pointer>, void>, std::pair<X1 const, void>>));
+    }
+
+    return boost::report_errors();
+}