From 64532c4792e5f0cb294dc9346004e44a21466d20 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Tue, 16 May 2023 02:37:59 +0300
Subject: [PATCH] Add support for (homogeneous) value lists to mp_append. Refs
 #53.

---
 include/boost/mp11/detail/mp_append.hpp       | 50 +++++++++++++++-
 .../boost/mp11/detail/mp_is_value_list.hpp    | 41 +++++++++++++
 test/Jamfile                                  |  1 +
 test/mp_append_3.cpp                          | 60 +++++++++++++++++++
 4 files changed, 151 insertions(+), 1 deletion(-)
 create mode 100644 include/boost/mp11/detail/mp_is_value_list.hpp
 create mode 100644 test/mp_append_3.cpp

diff --git a/include/boost/mp11/detail/mp_append.hpp b/include/boost/mp11/detail/mp_append.hpp
index 937d15e..840a524 100644
--- a/include/boost/mp11/detail/mp_append.hpp
+++ b/include/boost/mp11/detail/mp_append.hpp
@@ -8,6 +8,8 @@
 //  See accompanying file LICENSE_1_0.txt or copy at
 //  http://www.boost.org/LICENSE_1_0.txt
 
+#include <boost/mp11/detail/mp_count.hpp>
+#include <boost/mp11/detail/mp_is_value_list.hpp>
 #include <boost/mp11/detail/mp_list.hpp>
 #include <boost/mp11/utility.hpp>
 #include <boost/mp11/detail/config.hpp>
@@ -153,6 +155,44 @@ template<
     using type = typename mp_append_impl<prefix, Lr...>::type;
 };
 
+#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+template<class... L> struct append_value_impl
+{
+};
+
+template<template<auto...> class L, auto... A>
+struct append_value_impl<L<A...>>
+{
+    using type = L<A...>;
+};
+
+template<template<auto...> class L1, auto... A1, template<auto...> class L2, auto... A2>
+struct append_value_impl<L1<A1...>, L2<A2...>>
+{
+    using type = L1<A1..., A2...>;
+};
+
+template<template<auto...> class L1, auto... A1, template<auto...> class L2, auto... A2, template<auto...> class L3, auto... A3>
+struct append_value_impl<L1<A1...>, L2<A2...>, L3<A3...>>
+{
+    using type = L1<A1..., A2..., A3...>;
+};
+
+template<template<auto...> class L1, auto... A1, template<auto...> class L2, auto... A2, template<auto...> class L3, auto... A3, template<auto...> class L4, auto... A4>
+struct append_value_impl<L1<A1...>, L2<A2...>, L3<A3...>, L4<A4...>>
+{
+    using type = L1<A1..., A2..., A3..., A4...>;
+};
+
+template<template<auto...> class L1, auto... A1, template<auto...> class L2, auto... A2, template<auto...> class L3, auto... A3, template<auto...> class L4, auto... A4, template<auto...> class L5, auto... A5, class... Lr>
+struct append_value_impl<L1<A1...>, L2<A2...>, L3<A3...>, L4<A4...>, L5<A5...>, Lr...>
+{
+    using type = typename append_value_impl<L1<A1..., A2..., A3..., A4..., A5...>, Lr...>::type;
+};
+
+#endif
+
 #if BOOST_MP11_WORKAROUND( BOOST_MP11_CUDA, >= 9000000 && BOOST_MP11_CUDA < 10000000 )
 
 template<class... L>
@@ -167,7 +207,15 @@ template<class... L> struct mp_append_impl: mp_append_impl_cuda_workaround<L...>
 
 #else
 
-template<class... L> struct mp_append_impl: mp_if_c<(sizeof...(L) > 111), mp_quote<append_inf_impl>, mp_if_c<(sizeof...(L) > 11), mp_quote<append_111_impl>, mp_quote<append_11_impl> > >::template fn<L...>
+template<class... L> struct mp_append_impl:
+    mp_cond<
+#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+        mp_bool<(sizeof...(L) > 0 && sizeof...(L) == mp_count_if<mp_list<L...>, mp_is_value_list>::value)>, mp_quote<append_value_impl>,
+#endif
+        mp_bool<(sizeof...(L) > 111)>, mp_quote<append_inf_impl>,
+        mp_bool<(sizeof...(L) > 11)>, mp_quote<append_111_impl>,
+        mp_true, mp_quote<append_11_impl>
+    >::template fn<L...>
 {
 };
 
diff --git a/include/boost/mp11/detail/mp_is_value_list.hpp b/include/boost/mp11/detail/mp_is_value_list.hpp
new file mode 100644
index 0000000..8f94f03
--- /dev/null
+++ b/include/boost/mp11/detail/mp_is_value_list.hpp
@@ -0,0 +1,41 @@
+#ifndef BOOST_MP11_DETAIL_MP_IS_VALUE_LIST_HPP_INCLUDED
+#define BOOST_MP11_DETAIL_MP_IS_VALUE_LIST_HPP_INCLUDED
+
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/detail/config.hpp>
+
+namespace boost
+{
+namespace mp11
+{
+
+// mp_is_value_list<L>
+namespace detail
+{
+
+template<class L> struct mp_is_value_list_impl
+{
+    using type = mp_false;
+};
+
+#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+template<template<auto...> class L, auto... A> struct mp_is_value_list_impl<L<A...>>
+{
+    using type = mp_true;
+};
+
+#endif
+
+} // namespace detail
+
+template<class L> using mp_is_value_list = typename detail::mp_is_value_list_impl<L>::type;
+
+} // namespace mp11
+} // namespace boost
+
+#endif // #ifndef BOOST_MP11_DETAIL_MP_IS_VALUE_LIST_HPP_INCLUDED
diff --git a/test/Jamfile b/test/Jamfile
index 62bb206..e6b8d2a 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -49,6 +49,7 @@ run mp_rename.cpp ;
 run mp_rename_2.cpp ;
 run mp_append.cpp ;
 run mp_append_2.cpp ;
+run mp_append_3.cpp ;
 run mp_append_sf.cpp ;
 run mp_replace_front.cpp ;
 run mp_replace_front_2.cpp ;
diff --git a/test/mp_append_3.cpp b/test/mp_append_3.cpp
new file mode 100644
index 0000000..2f134e6
--- /dev/null
+++ b/test/mp_append_3.cpp
@@ -0,0 +1,60 @@
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/list.hpp>
+
+#if !defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+#pragma message("Test skipped because BOOST_MP11_HAS_TEMPLATE_AUTO is not defined")
+int main() {}
+
+#else
+
+#include <boost/core/lightweight_test_trait.hpp>
+
+template<auto... A> struct L1 {};
+template<int... I> struct L2 {};
+
+int main()
+{
+    using boost::mp11::mp_list_v;
+    using boost::mp11::mp_append;
+
+    //
+
+    {
+        using L1 = mp_list_v<false, 1>;
+        using L2 = mp_list_v<false, 2>;
+        using L3 = mp_list_v<false, 3>;
+        using L4 = mp_list_v<false, 4>;
+
+        BOOST_TEST_TRAIT_SAME(mp_append<L1>, mp_list_v<false, 1>);
+        BOOST_TEST_TRAIT_SAME(mp_append<L1, L2>, mp_list_v<false, 1, false, 2>);
+        BOOST_TEST_TRAIT_SAME(mp_append<L1, L2, L3>, mp_list_v<false, 1, false, 2, false, 3>);
+        BOOST_TEST_TRAIT_SAME(mp_append<L1, L2, L3, L4>, mp_list_v<false, 1, false, 2, false, 3, false, 4>);
+    }
+
+    //
+
+    BOOST_TEST_TRAIT_SAME(mp_append<L1<>>, L1<>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L1<>, L2<1>>, L1<1>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L1<>, L2<1>, L1<true>>, L1<1, true>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L1<>, L2<1>, L1<true>, L2<2>>, L1<1, true, 2>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L1<>, L2<1>, L1<true>, L2<2>, L1<false>>, L1<1, true, 2, false>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L1<>, L2<1>, L1<true>, L2<2>, L1<false>, L2<3>>, L1<1, true, 2, false, 3>);
+
+    //
+
+    BOOST_TEST_TRAIT_SAME(mp_append<L2<1>>, L2<1>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L2<1>, L2<2>>, L2<1, 2>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L2<1>, L2<2>, L2<3>>, L2<1, 2, 3>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L2<1>, L2<2>, L2<3>, L2<4>>, L2<1, 2, 3, 4>);
+    BOOST_TEST_TRAIT_SAME(mp_append<L2<1>, L2<2>, L2<3>, L2<4>, L2<5>>, L2<1, 2, 3, 4, 5>);
+
+    //
+
+    return boost::report_errors();
+}
+
+#endif