Add support for value lists to mp_size. Refs #53.

include/boost/mp11/list.hpp

@@ -42,6 +42,15 @@ template<template<class...> class L, class... T> struct mp_size_impl<L<T...>>
     using type = mp_size_t<sizeof...(T)>;
 };
 
+#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+template<template<auto...> class L, auto... A> struct mp_size_impl<L<A...>>
+{
+    using type = mp_size_t<sizeof...(A)>;
+};
+
+#endif
+
 } // namespace detail
 
 template<class L> using mp_size = typename detail::mp_size_impl<L>::type;

test/Jamfile

@@ -26,6 +26,7 @@ compile mp11.cpp ;
 
 # list
 run mp_size.cpp ;
+run mp_size_2.cpp ;
 run mp_empty.cpp ;
 run mp_front.cpp ;
 run mp_pop_front.cpp ;

test/mp_size_2.cpp

@@ -0,0 +1,38 @@
+// 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/mp11/integral.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+
+template<auto... A> struct L1 {};
+template<int... A> struct L2 {};
+
+int main()
+{
+    using boost::mp11::mp_size;
+    using boost::mp11::mp_size_t;
+
+    BOOST_TEST_TRAIT_SAME(mp_size<L1<>>, mp_size_t<0>);
+    BOOST_TEST_TRAIT_SAME(mp_size<L1<false>>, mp_size_t<1>);
+    BOOST_TEST_TRAIT_SAME(mp_size<L1<false, 0>>, mp_size_t<2>);
+    BOOST_TEST_TRAIT_SAME(mp_size<L1<false, 0, std::size_t(0)>>, mp_size_t<3>);
+
+    BOOST_TEST_TRAIT_SAME(mp_size<L2<>>, mp_size_t<0>);
+    BOOST_TEST_TRAIT_SAME(mp_size<L2<0>>, mp_size_t<1>);
+    BOOST_TEST_TRAIT_SAME(mp_size<L2<0, 1>>, mp_size_t<2>);
+    BOOST_TEST_TRAIT_SAME(mp_size<L2<0, 1, 2>>, mp_size_t<3>);
+
+    return boost::report_errors();
+}
+
+#endif