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 +1,81 @@
+/*!
+@file
+Defines `boost::hana::zero`.
+
+@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_ZERO_HPP
+#define BOOST_HANA_ZERO_HPP
+
+#include <boost/hana/fwd/zero.hpp>
+
+#include <boost/hana/concept/constant.hpp>
+#include <boost/hana/concept/monoid.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/to.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/detail/canonical_constant.hpp>
+
+#include <type_traits>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    template <typename M>
+    struct zero_t {
+    #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+        static_assert(hana::Monoid<M>::value,
+        "hana::zero<M>() requires 'M' to be a Monoid");
+    #endif
+
+        constexpr decltype(auto) operator()() const {
+            using Zero = BOOST_HANA_DISPATCH_IF(zero_impl<M>,
+                hana::Monoid<M>::value
+            );
+
+            return Zero::apply();
+        }
+    };
+
+    template <typename M, bool condition>
+    struct zero_impl<M, when<condition>> : default_ {
+        template <typename ...Args>
+        static constexpr auto apply(Args&& ...) = delete;
+    };
+
+    //////////////////////////////////////////////////////////////////////////
+    // Model for non-boolean arithmetic data types
+    //////////////////////////////////////////////////////////////////////////
+    template <typename T>
+    struct zero_impl<T, when<
+        std::is_arithmetic<T>::value &&
+        !std::is_same<T, bool>::value
+    >> {
+        static constexpr T apply()
+        { return static_cast<T>(0); }
+    };
+
+    //////////////////////////////////////////////////////////////////////////
+    // Model for Constants over a Monoid
+    //////////////////////////////////////////////////////////////////////////
+    namespace detail {
+        template <typename C>
+        struct constant_from_zero {
+            static constexpr auto value = hana::zero<typename C::value_type>();
+            using hana_tag = detail::CanonicalConstant<typename C::value_type>;
+        };
+    }
+
+    template <typename C>
+    struct zero_impl<C, when<
+        hana::Constant<C>::value &&
+        Monoid<typename C::value_type>::value
+    >> {
+        static constexpr decltype(auto) apply()
+        { return hana::to<C>(detail::constant_from_zero<C>{}); }
+    };
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_ZERO_HPP