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 +1,51 @@
+/*!
+@file
+Forward declares `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_FWD_EMPTY_HPP
+#define BOOST_HANA_FWD_EMPTY_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/when.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! Identity of the monadic combination `concat`.
+    //! @ingroup group-MonadPlus
+    //!
+    //! Signature
+    //! ---------
+    //! Given a MonadPlus `M`, the signature is
+    //! @f$ \mathtt{empty}_M : \emptyset \to M(T) @f$.
+    //!
+    //! @tparam M
+    //! The tag of the monadic structure to return. This must be
+    //! a model of the MonadPlus concept.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/empty.cpp
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    template <typename M>
+    constexpr auto empty = []() {
+        return tag-dispatched;
+    };
+#else
+    template <typename M, typename = void>
+    struct empty_impl : empty_impl<M, when<true>> { };
+
+    template <typename M>
+    struct empty_t;
+
+    template <typename M>
+    constexpr empty_t<M> empty{};
+#endif
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_FWD_EMPTY_HPP