stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

2026-02-24 18:38:47 +00:00
parent da8c28aaeb
commit 65cb2619a7
13106 changed files with 2484322 additions and 1804 deletions
@@ -0,0 +1,53 @@
+/*!
+@file
+Defines `boost::hana::empty`.
+
+@copyright Louis Dionne 2013-2017
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_EMPTY_HPP
+#define BOOST_HANA_EMPTY_HPP
+
+#include <boost/hana/fwd/empty.hpp>
+
+#include <boost/hana/concept/monad_plus.hpp>
+#include <boost/hana/concept/sequence.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/core/make.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    template <typename M>
+    struct empty_t {
+    #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+        static_assert(hana::MonadPlus<M>::value,
+        "hana::empty<M>() requires 'M' to be a MonadPlus");
+    #endif
+
+        constexpr auto operator()() const {
+            using Empty = BOOST_HANA_DISPATCH_IF(empty_impl<M>,
+                hana::MonadPlus<M>::value
+            );
+
+            return Empty::apply();
+        }
+    };
+
+    template <typename M, bool condition>
+    struct empty_impl<M, when<condition>> : default_ {
+        template <typename ...Args>
+        static constexpr auto apply(Args&& ...) = delete;
+    };
+
+    template <typename S>
+    struct empty_impl<S, when<Sequence<S>::value>> {
+        static constexpr auto apply() {
+            return hana::make<S>();
+        }
+    };
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_EMPTY_HPP