Add mp_power_set

include/boost/mp11/algorithm.hpp

@@ -1127,6 +1127,37 @@ template<class L, class N> using mp_rotate_right = mp_rotate_right_c<L, std::siz
 // mp_max_element<L, P>
 //   in detail/mp_min_element.hpp
 
+// mp_power_set<L>
+namespace detail
+{
+
+template<class L> struct mp_power_set_impl;
+
+} // namespace detail
+
+template<class L> using mp_power_set = typename detail::mp_power_set_impl<L>::type;
+
+namespace detail
+{
+
+template<template<class...> class L> struct mp_power_set_impl< L<> >
+{
+    using type = L< L<> >;
+};
+
+template<template<class...> class L, class T1, class... T> struct mp_power_set_impl< L<T1, T...> >
+{
+    using S1 = mp_power_set< L<T...> >;
+
+    template<class L2> using _f = mp_push_front<L2, T1>;
+
+    using S2 = mp_transform<_f, S1>;
+
+    using type = mp_append< S1, S2 >;
+};
+
+} // namespace detail
+
 } // namespace mp11
 } // namespace boost
 

test/Jamfile

@@ -119,6 +119,7 @@ run mp_pop_back.cpp ;
 run mp_flatten.cpp ;
 run mp_rotate_left.cpp ;
 run mp_rotate_right.cpp ;
+run mp_power_set.cpp ;
 
 # integral
 run integral.cpp ;

test/mp_power_set.cpp

@@ -0,0 +1,33 @@
+// Copyright 2020 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/algorithm.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
+#include <tuple>
+
+struct X1 {};
+struct X2 {};
+struct X3 {};
+
+int main()
+{
+    using boost::mp11::mp_list;
+    using boost::mp11::mp_power_set;
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< mp_list<> >, mp_list<mp_list<>> >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< mp_list<X1> >, mp_list< mp_list<>, mp_list<X1> > >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< mp_list<X2, X1> >, mp_list< mp_list<>, mp_list<X1>, mp_list<X2>, mp_list<X2, X1> > >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< mp_list<X1, X1> >, mp_list< mp_list<>, mp_list<X1>, mp_list<X1>, mp_list<X1, X1> > >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< mp_list<X3, X2, X1> >, mp_list< mp_list<>, mp_list<X1>, mp_list<X2>, mp_list<X2, X1>, mp_list<X3>, mp_list<X3, X1>, mp_list<X3, X2>, mp_list<X3, X2, X1> > >));
+
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< std::tuple<> >, std::tuple<std::tuple<>> >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< std::tuple<X1> >, std::tuple< std::tuple<>, std::tuple<X1> > >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< std::tuple<X2, X1> >, std::tuple< std::tuple<>, std::tuple<X1>, std::tuple<X2>, std::tuple<X2, X1> > >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< std::tuple<X1, X1> >, std::tuple< std::tuple<>, std::tuple<X1>, std::tuple<X1>, std::tuple<X1, X1> > >));
+    BOOST_TEST_TRAIT_TRUE((std::is_same< mp_power_set< std::tuple<X3, X2, X1> >, std::tuple< std::tuple<>, std::tuple<X1>, std::tuple<X2>, std::tuple<X2, X1>, std::tuple<X3>, std::tuple<X3, X1>, std::tuple<X3, X2>, std::tuple<X3, X2, X1> > >));
+
+    return boost::report_errors();
+}