Add value list support to mp_fill. Refs #53.

include/boost/mp11/algorithm.hpp

@@ -199,7 +199,10 @@ template<class Q, class... L> using mp_filter_q = typename detail::mp_filter_imp
 namespace detail
 {
 
-template<class L, class V> struct mp_fill_impl;
+template<class L, class V> struct mp_fill_impl
+{
+// An error "no type named 'type'" here means that the L argument of mp_fill is not a list
+};
 
 template<template<class...> class L, class... T, class V> struct mp_fill_impl<L<T...>, V>
 {
@@ -216,6 +219,15 @@ template<template<class...> class L, class... T, class V> struct mp_fill_impl<L<
 #endif
 };
 
+#if defined(BOOST_MP11_HAS_TEMPLATE_AUTO)
+
+template<template<auto...> class L, auto... A, class V> struct mp_fill_impl<L<A...>, V>
+{
+    using type = L<((void)A, V::value)...>;
+};
+
+#endif
+
 } // namespace detail
 
 template<class L, class V> using mp_fill = typename detail::mp_fill_impl<L, V>::type;

test/Jamfile

@@ -79,6 +79,7 @@ run mp_transform_if.cpp ;
 run mp_transform_if_q.cpp ;
 run mp_filter.cpp ;
 run mp_fill.cpp ;
+run mp_fill_2.cpp ;
 run mp_count.cpp ;
 run mp_count_if.cpp ;
 run mp_count_if_q.cpp ;

test/mp_fill_2.cpp

@@ -0,0 +1,40 @@
+// Copyright 2023 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/integral.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 V1 {};
+template<int... I> struct V2 {};
+
+int main()
+{
+    using boost::mp11::mp_fill;
+    using boost::mp11::mp_int;
+
+    BOOST_TEST_TRAIT_SAME(mp_fill<V1<>, mp_int<-1>>, V1<>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V1<false>, mp_int<-1>>, V1<-1>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V1<false, 0>, mp_int<-1>>, V1<-1, -1>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V1<false, 0, true>, mp_int<-1>>, V1<-1, -1, -1>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V1<false, 0, true, std::size_t(1)>, mp_int<-1>>, V1<-1, -1, -1, -1>);
+
+    BOOST_TEST_TRAIT_SAME(mp_fill<V2<>, mp_int<-1>>, V2<>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V2<0>, mp_int<-1>>, V2<-1>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V2<0, 1>, mp_int<-1>>, V2<-1, -1>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V2<0, 1, 2>, mp_int<-1>>, V2<-1, -1, -1>);
+    BOOST_TEST_TRAIT_SAME(mp_fill<V2<0, 1, 2, 3>, mp_int<-1>>, V2<-1, -1, -1, -1>);
+
+    return boost::report_errors();
+}
+
+#endif