From 3a31eeee29f3aa166f922c94aeb197b2b3fa763b Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Mon, 7 Jan 2019 21:02:30 +0200
Subject: [PATCH] Add mp_set_difference

---
 include/boost/mp11/set.hpp | 15 ++++++++++++
 test/Jamfile               |  1 +
 test/mp_set_difference.cpp | 48 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 test/mp_set_difference.cpp

diff --git a/include/boost/mp11/set.hpp b/include/boost/mp11/set.hpp
index 413af7a..b3917db 100644
--- a/include/boost/mp11/set.hpp
+++ b/include/boost/mp11/set.hpp
@@ -9,8 +9,10 @@
 // http://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/mp11/utility.hpp>
+#include <boost/mp11/function.hpp>
 #include <boost/mp11/detail/mp_list.hpp>
 #include <boost/mp11/detail/mp_append.hpp>
+#include <boost/mp11/detail/mp_remove_if.hpp>
 #include <type_traits>
 
 namespace boost
@@ -131,6 +133,19 @@ 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_difference<L, S...>
+namespace detail
+{
+
+template<class... S> struct in_any_set
+{
+    template<class T> using fn = mp_any< mp_set_contains<S, T>... >;
+};
+
+} // namespace detail
+
+template<class L, class... S> using mp_set_difference = mp_remove_if_q<L, detail::in_any_set<S...>>;
+
 } // namespace mp11
 } // namespace boost
 
diff --git a/test/Jamfile b/test/Jamfile
index 010309b..ba34e7a 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -135,6 +135,7 @@ run mp_set_push_front.cpp ;
 run mp_is_set.cpp ;
 run mp_set_union.cpp ;
 run mp_set_union_sf.cpp ;
+run mp_set_difference.cpp ;
 
 # function
 run mp_all.cpp ;
diff --git a/test/mp_set_difference.cpp b/test/mp_set_difference.cpp
new file mode 100644
index 0000000..9e21f40
--- /dev/null
+++ b/test/mp_set_difference.cpp
@@ -0,0 +1,48 @@
+
+// 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_difference;
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<>>, mp_list<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void>>, mp_list<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int>>, mp_list<void, int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float>>, mp_list<void, int, float>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<>, std::pair<float, int>>, std::tuple<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<void>, std::pair<float, int>>, std::tuple<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<void, int>, std::pair<float, int>>, std::tuple<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<void, int, float>, std::pair<float, int>>, std::tuple<void>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float>, std::tuple<>>, mp_list<void, int, float>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float>, std::tuple<int>>, mp_list<void, float>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float>, std::tuple<float, void>>, mp_list<int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float>, std::tuple<float, void, int>>, mp_list<>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<>, mp_list<>, std::pair<float, int>>, std::tuple<>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<void>, mp_list<double>, std::pair<float, int>>, std::tuple<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<void, int>, mp_list<double, int>, std::pair<float, int>>, std::tuple<void>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<std::tuple<void, int, float>, mp_list<double, int, float>, std::pair<float, int>>, std::tuple<void>>));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<>>, mp_list<int, float>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<int>>, mp_list<float>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<float, void>>, mp_list<int>>));
+    BOOST_TEST_TRAIT_TRUE((std::is_same<mp_set_difference<mp_list<void, int, float, double>, std::pair<double, void>, std::tuple<float, void, int>>, mp_list<>>));
+
+    return boost::report_errors();
+}