From 311f8bf1a596b1f5b388c0b66dec48d8dd02bcaa Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Mon, 7 Jan 2019 22:30:58 +0200
Subject: [PATCH] Add mp_set_intersection

---
 include/boost/mp11/set.hpp   | 29 +++++++++++++++++++++
 test/Jamfile                 |  1 +
 test/mp_set_intersection.cpp | 49 ++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+)
 create mode 100644 test/mp_set_intersection.cpp

diff --git a/include/boost/mp11/set.hpp b/include/boost/mp11/set.hpp
index 54f5f42..45ba982 100644
--- a/include/boost/mp11/set.hpp
+++ b/include/boost/mp11/set.hpp
@@ -12,6 +12,7 @@
 #include <boost/mp11/function.hpp>
 #include <boost/mp11/detail/mp_list.hpp>
 #include <boost/mp11/detail/mp_append.hpp>
+#include <boost/mp11/detail/mp_copy_if.hpp>
 #include <boost/mp11/detail/mp_remove_if.hpp>
 #include <boost/mp11/detail/mp_is_list.hpp>
 #include <type_traits>
@@ -134,6 +135,34 @@ template<class L1, class L2, class L3, class... L> struct mp_set_union_impl<L1,
 
 template<class... L> using mp_set_union = typename detail::mp_set_union_impl<L...>::type;
 
+// mp_set_intersection<S...>
+namespace detail
+{
+
+template<class... S> struct in_all_sets
+{
+    template<class T> using fn = mp_all< mp_set_contains<S, T>... >;
+};
+
+template<class L, class... S> using mp_set_intersection_ = mp_copy_if_q<L, detail::in_all_sets<S...>>;
+
+template<class... S> struct mp_set_intersection_impl
+{
+};
+
+template<> struct mp_set_intersection_impl<>
+{
+    using type = mp_list<>;
+};
+
+template<class L, class... S> struct mp_set_intersection_impl<L, S...>: mp_defer<mp_set_intersection_, L, S...>
+{
+};
+
+} // namespace detail
+
+template<class... S> using mp_set_intersection = typename detail::mp_set_intersection_impl<S...>::type;
+
 // mp_set_difference<L, S...>
 namespace detail
 {
diff --git a/test/Jamfile b/test/Jamfile
index ba715e3..16509e6 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -137,6 +137,7 @@ run mp_set_union.cpp ;
 run mp_set_union_sf.cpp ;
 run mp_set_difference.cpp ;
 run mp_set_difference_sf.cpp ;
+run mp_set_intersection.cpp ;
 
 # function
 run mp_all.cpp ;
diff --git a/test/mp_set_intersection.cpp b/test/mp_set_intersection.cpp
new file mode 100644
index 0000000..d9e16dd
--- /dev/null
+++ b/test/mp_set_intersection.cpp
@@ -0,0 +1,49 @@
+
+// Copyright 2019 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/set.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
+#include <tuple>
+#include <utility>
+
+int main()
+{
+    using boost::mp11::mp_list;
+    using boost::mp11::mp_set_intersection;
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<>, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<>>, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void>>, mp_list<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int>>, mp_list<void, int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float>>, mp_list<void, int, float>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<>, std::pair<float, int>>, std::tuple<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<void>, std::pair<float, int>>, std::tuple<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<void, int>, std::pair<float, int>>, std::tuple<int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<void, int, float>, std::pair<float, int>>, std::tuple<int, float>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float>, std::tuple<>>, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float>, std::tuple<int>>, mp_list<int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float>, std::tuple<float, void>>, mp_list<void, float>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float>, std::tuple<float, void, int>>, mp_list<void, int, float>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<>, mp_list<>, std::pair<float, int>>, std::tuple<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<void>, mp_list<double>, std::pair<float, int>>, std::tuple<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<void, int>, mp_list<double, int>, std::pair<float, int>>, std::tuple<int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<std::tuple<void, int, float>, mp_list<double, int, float>, std::pair<float, int>>, std::tuple<int, float>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<>>, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<int>>, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<float, void>>, mp_list<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_intersection<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<float, void, int>>, mp_list<void>>));
+
+    return boost::report_errors();
+}